ñ ¢ « ╝ ╔ └! )$ ╪( æ- ─3 ±7 P: u? ╔A ┴E ┌J `P áT MY Ñ\ b Ge i Vk p Us ∞w Ay Ä~ éç äA Molecule Is Born
4 Billion BC
EARTH
All life forms are made mostly of a few common atoms such as hydrogen, oxygen, nitrogen and carbon. These atoms stick together in groups called molecules. Atoms are like the letters of the alphabet; molecules are like words formed from those letters. A few letters can make an endless variety of words.
Many scientists think that after the earth formed the atmosphere consisted mainly of hydrogen, ammonia, and methane.
These, dissolved in the ocean, were the basic ingredients of life. The chemicals mixed in the water, forming a soup of more complicated molecules. Sunlight provided the energy to cook the soup. Lightning accelerated the process, helping more complex chains of carbon atoms to form.
By recreating what they believe the surface of the early earth must have been like, scientists have created some of the organic compounds from which life is built, but they are still far from creating life.
For life to exist, carbon is very special. Most atoms can only stick to themselves in small clusters. But carbon is unusual in that its atoms can stick to each other in endless chains, like sticky marbles.
Perhaps when conditions were perfect some complicated molecules formed in the early seas, then broke into two identical halves. Then, when the right molecules ("food") stuck on them, they might have formed identical copies of themselves.
This would have been the first self-reproducing molecule, meaning that it made identical copies of itself, like a tiny photocopy machine. Each of those copies could then split in two and form more and more copies, multiplying throughout the oceans like rabbits. Perhaps this was how life began.
åAlbertosaurus: Tyranno's Smaller Brother
70 Million BC;29 Feet;1.8 Tons
ALBERTA, CANADA
At 29 feet long, Albertosaurus was only about half the size of its closest cousin, Tyrannosaurus. Despite the difference in size, Albertosaurus was built in much the same way as its other meat-eating relatives. It had a large muscular head, a mouth full of sharp, serrated teeth and a powerful jaw that could deliver a fatal bone-crushing bite to the neck of its victims.
Like Tyrannosaurus, Albertosaurus had puny forearms that were too short to reach up to its mouth to feed. With only two functional fingers on its arms, as opposed to three, grasping for food would also have been very difficult. Some believe that Albertosaurus used these tiny limbs to hold on to females during mating. Others think they were used to help the dinosaur raise itself up when it was lying prone on the ground.
Paleontologists still wonder whether Albertosaurus and its flesh-eating relatives were fast-moving predators. Their bodies were too heavy to chase prey at high speeds for very long distances. More likely, Albertosaurus waited for its victims, then charged them at speeds of 18 or 20 miles an hour. Once close enough, Albertosaurus could clamp its powerful jaws down on the neck of its victim and then deliver a stunning blow with its powerful clawed legs.
LOCALITY: Alberta, Canada; Montana, USA
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Tyrannosauridae
╬Allosaurus: Giant Killer
150 Million BC;39 Feet;1-2 Tons
UTAH, UNITED STATES
Allosaurus, or "leaping reptile," was one of the most common types of dinosaurs known as "carnosaurs," or meat-eaters. It lived about 150 million years ago, roaming parts of western North America and Africa in search of prey. Though not nearly as large as its close relative Tyrannosaurus, Allosaurus was quite a fearsome killer. An adult Allosaurus could grow up to 39 feet long, 15 feet tall and weigh between 1 and 2 tons. As you can see in this movie, Allosaurus' skull was quite big in relation to its body -- almost 2.5 feet long -- and its jaws were lined with about 70 razor-sharp, curved, saw-edged teeth, just like the blade of a steak knife. These teeth pointed backwards so that huge pieces of meat could be forced down into Allosaurus' hungry mouth.
Allosaurus had short but strong front claws, and four large claws on each of its back feet, three of which helped to carry its weight. These claws also enabled Allosaurus to hold down and tear at its prey.
Scientists disagree about the hunting habits of Allosaurus. Some believe that the dinosaur was too large and clumsy to be a very effective hunter, while others argue that Allosaurus was quite agile and hunted down plant-eating dinosaurs in small packs. In fact, in North America, bones of Apatosaurus have been found with teeth marks that match those of Allosaurus!
LOCALITY: USA; Tanzania
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Allosauridae
5Self-Sufficient Eggs
400 Million BC
ON DRY LAND
Before reptiles could spend all their time on dry land they had to develop a new way to give birth to their young. No matter how much time amphibians spent living on dry land, they always had to return to the water in order to lay their eggs. That's because baby amphibians, known as larvae, were too small and frail to survive on land without being crushed or drying out.
So about 400 million years ago, certain amphibians began to lay a new kind of egg. It was called the "amniotic" egg. An amniotic egg is a specialized egg that is very similar to the eggs birds and lizards lay today. The first amniotic egg was covered by a leathery shell (not a hard shell like a chicken egg), and contained everything needed for a young, undeveloped animal, called an embryo, to grow into a fully functioning baby that would eventually crack through the shell.
Inside, the amniotic egg was divided into four major cavities that performed special functions to help the embryo develop. The main cavity held the embryo, which was surrounded by a fluid called the amnion that helped keep the embryo moist and cushion it from the vibrations of the outside world. Another cavity called the yolk contained a food supply for the embryo. The waste products from the growing embryo went into another cavity called the alantoic cavity. Finally, oxygen entered through tiny holes in the shell into an area known as the chorion.
With sturdy, self-sufficient eggs like these, reptiles were free to move as far they liked on land, inhabiting new terrain like grassy lands and dry, hot deserts.
FAnchisaurus: Typical Prosauropod
210 Million BC;7 Feet;60 Pounds
CONNECTICUT, UNITED STATES
Though Anchisaurus was found in 1818, it was not until 1885 that it was recognized as a dinosaur.
Anchisaurus (meaning "near reptile" since its body was found near the surface of the ground) had a slender nose, somewhat triangular head with diamond-shaped teeth that look like they would have been good for eating leaves. It also had a long neck, body and tail. Anchisaurus' long, narrow feet had large, curved thumb claws that it could probably use for digging up plants.
The arms of this Early Jurassic dinosaur were about a third as long as its back legs, so it probably spent most of its time walking on all fours, but may have stood on its back legs to reach food.
LOCALITY: USA and southern Africa
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Prosauropoda
FAMILY: Anchisauridae
kAnkylosaurus: The Armored Tank
72 Million BC; 33 Feet;4 Tons
ALBERTA, CANADA
Ankylosaurus was the armored tank of the dinosaurs. Massively built, this creature weighed close to four tons and measured 33 feet long, making it the largest of the group of armored dinosaurs known as ankylosaurs.
Few predators could pierce its tough defenses. Ankylosaurus was covered from the top of its solid skull to the tip of its powerful tail with bands of bony armor-plating and tall, hard spines. Even its eyelids were armored. Ankylosaurus had a broad body measuring 16 feet across. Its skull alone was up to 2-1/2 feet long with sturdy triangular horns at the corners of its head. One of the most interesting characteristics of Ankylosaurus was the heavy, bony club at the end of its tail. Made of fused bone embedded in leathery hide, this acted as a lethal weapon against most ferocious predators.
Ankylosaurus was among the last dinosaurs to survive the Cretaceous Period and lived primarily in North America. They were plant eaters and may have lived together in small groups.
LOCALITY: Alberta, Canada; Montana, USA
ORDER: Ornithiscia
SUBORDER: Ankylosauria
FAMILY: Ankylosauridae
hApatosaurus: The Long Necked Dinosaur
145 Million BC;70 Feet;33 Tons
UTAH, UNITED STATES
As you can see in this movie, Apatosaurus had a very long neck. It took advantage of its neck to reach the leaves and branches on the tops of trees, using its massive tail for support while standing on its rear legs. It had to eat tons of plants and leaves every day just to maintain its incredible body weight.
These were not slow, defenseless creatures, either. In a battle with its enemy Allosaurus, Apatosaurus could have reared up on its hind legs and then brought its entire body down on its predator. Apatosaurus' long tail was also not a bad whip.
Recently, Dinamation International Society has discovered what may be the largest Apatosaurus skeleton ever found. It may have measured up to 95 feet long!
LOCALITY: Oklahoma, Utah, Wyoming, USA
ORDER: Saurischia
SUBORDER: Sauropodorpha
INFRAORDER: Sauropoda
FAMILY: Diplodocidae
Apatosaurus: Thunder Lizard
141 Million BC;70 Feet;33 Tons
UTAH, UNITED STATES
First, there is the crashing sound of plants and trees being trampled. Then, the terrible shaking of the earth. In the distance, an immense shape the size of a small building appears. Apatosaurus used to be called "Brontosaurus," which meant "thunder lizard" and referred to the loud noise this enormous dinosaur must have made as its 33-ton body lumbered across the plains of North America. Scientists no longer use the name Brontosaurus because the first fossils to be discovered of this creature were actually given the name Apatosaurus.
Apatosaurus was one of the largest animals ever to walk the earth. It belonged to the group of plant-eating Sauropods that included Diplodocus and Camarasaurus. Like these other dinosaurs, Apatosaurus had a very long neck and an even longer tail. An adult Apatosaurus measured up to 70 feet in length and had a tiny head in comparison to its body: only 22 inches long! Although not as long as its close relative Diplodocus, Apatosaurus weighed nearly three times as much, primarily because its bones were denser and its heavy tail was made up of almost 82 interlocking vertebrae.
LOCALITY: Oklahoma, Utah, Wyoming, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Diplodocidae
XArchaeopteryx: The Early Bird
140 Million BC;14 Inches;5 Pounds
SOLNHOFEN, GERMANY
In 1861, when German stone cutters discovered the nearly perfect fossil imprint of Archaeopteryx in a block of 140-million-year-old limestone in a stone quarry, they didn't know what to make of it. At first, scientists thought the fossil was the imprint of a tiny meat-eating dinosaur. Then they realized that the faint outlines surrounding the skeleton were actually imprints of feathers.
As it turned out, the discovery of Archaeopteryx was one of the most important finds ever. It proved what many scientists had long believed. There was a strong link between the dinosaurs of long ago and the birds we know today.
Indeed, Archaeopteryx was something of a cross between a dinosaur and a modern bird. About the same size as a pigeon, it had a small head, large eyes and feathers which covered most of its body. But like dinosaurs, Archaeopteryx had teeth in its jaw, claws on its fingers and a long, bony tail. Also, the bones throughout its body were much heavier than a bird's and it didn't have as many muscles with which to flap its wings. Instead of flying, Archaeopteryx probably used its wings to fly short distances or glide from tree to tree catching insects or occasionally attacking small animals on the ground.
LOCALITY: Germany
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Coelurosauria
FAMILY: Archaeopterygidae
Avimimus: The Bird Mimic
82 Million BC;5 Feet;130 Pounds
MONGOLIA
This small dinosaur found in 1981 had some interesting birdlike features, but is it related to birds?
Avimimus, or "bird mimic" had a large brain and toothless beak, plus a ridge along the back edge of its forearm that resembled the bumps on bird skeletons to which feathers are attached.
Perhaps Avimimus had feathers on its arms. It was possible that Avimimus ran along and used its feathered arms to take quick jumps and to swat bugs to eat.
Though it sounds conceivable, Avimimus is not believed to be ancestral to birds because it came tens of millions of years after Archaeopteryx, a small flying dinosaur that is considered to be the first bird.
Many palaeontologists also doubt that Avimimus had feathers. This is because feathers are extremely complicated -- much more complex than they look -- and scientists find it difficult to believe that feathers could have evolved twice.
LOCALITY: Mongolia, China
ORDER: Saurischia
SUBORDER: Therapoda
INFRAORDER: Oviraptorosauria
FAMILY: Avimimidae
┬A Singular Big Bang
15 Billion BC
UNIVERSE
Most scientists believe the universe began from a "singularity," an impossible-to-imagine point so small that it had no size at all. Then that point, which they think contained everything that there is in the universe -- matter, energy, and even time and space -- exploded with an enormous rush.
Scientists don't know what caused this point to explode in a "Big Bang" about 15 billion years ago, and they don't know what -- if anything -- existed before the bang occurred, or even if there was a "before" before it happened.
So-called "black holes" are believed to be similar to this singularity except that they contain far less of the universe. Black holes are believed to be collapsed stars of such density and gravitational strength that once caught, nothing -- not even light -- can escape their pull.
Scientists believe that as the Big Bang exploded outward in a blaze of energy, the universe was blown up like a child blows up a balloon.
│Heavy Elements Created
15 Billion BC
UNIVERSE
Scientists believe that as the universe expanded following the Big Bang, it cooled rapidly and some of its energy condensed into tiny particles. Then an unexplained phenomenon called electromagnetic force began pulling these tiny particles together into hydrogen atoms.
Gravity, another mysterious force, caused more atoms to gather. The larger these clouds of atoms, the stronger the gravitational force became, until the pressure squeezed the atoms so hard that it sparked a nuclear reaction and the clouds became huge balls of fire. Stars blinked on all over the universe.
These stars burned at tremendously high temperatures as their hydrogen atoms joined to form helium atoms in a process called fusion. Small stars can burn like this for billions of years, until they run out of hydrogen. Then they cool down and collapse, becoming white dwarfs. But the largest stars burn up much more quickly, then collapse, fusing their atoms together into heavier elements. Finally they explode into supernovas, scattering new atoms of copper, gold, uranium and many other elements into the surrounding galaxy.
The earth and all its plants and animals were formed from these heavier elements.
Baryonyx: Fishing Dinosaur
120 Million BC;26 Feet;2 Tons
SUSSEX, ENGLAND
Baryonyx is a recently discovered dinosaur that appears to have been especially well suited for fishing. If so, it is the only known fishing dinosaur.
Baryonyx's nostrils were set back from the tip of its long, narrow, crocodile-like snout, perhaps so it could stick its nose underwater and still breathe. It had a mouth full of small, sharp teeth -- twice as many teeth as most dinosaurs -- which were probably great for catching fish.
Baryonyx, meaning "heavy claw," takes its name from the two huge, curved claws, more than a foot long, that seem to have been attached to its front feet, where they would be handy for spearing fish. However, since the claws were not attached to the skeleton, scientists are not certain whether they were on the front or back feet.)
Another piece of evidence for Baryonyx's fishy diet is that scientists have found the remains of a fish dinner where its stomach would have been.
Because of its long front legs, scientists believe Baryonyx may have walked part of the time on all four legs.
Baryonyx was discovered in 1983 by an amateur fossil hunter in Sussex, England, and is related to the Spinosaurus.
LOCALITY: England
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Baryonychidae
~ Was Earth Made in 4004 BC?
1654 AD
DUBLIN, IRELAND
Though lots of dinosaur bones have been found and scientists estimate the universe is billions of years old, not everybody believes it. Some religious people prefer to believe the estimate of 16th Century Anglican Archbishop James Ussher, who thought the earth began about 6,000 years ago.
One explanation of how Earth could be so young when there is such evidence of its age is that God created a "mature universe." In such a case, stars would shine on the night they were created, though light years away; trees would have yearly rings, though they were minutes old; there would be decomposed organic matter in the soil, though no plants had ever grown before, and so forth.
This is a philosophical explanation, not a scientific one, since it suggests the evidence does not point where it seems to point.
However, many religious scholars accept scientists' estimates of the age of the universe. In fact, they feel the discovery that the universe had a beginning is evidence that someone -- God -- must have started it.
Also, the discovery that the "constants of physics" at the basis of the universe seem precisely adjusted for life seems to many to argue for a Great Designer. For example, if gravity was a bit stronger, stars would burn out too quickly for planets suitable for life to develop. If it was a bit weaker, they wouldn't create the heavy elements necessary for life.
A recent explanation of how the biblical story of creation and science mesh belongs to astronomer and former Caltech fellow, Dr. Hugh Ross. He updates an earlier explanation, that creation "days" were actually long ages.
In outline, this is his explanation: "In the beginning God created the heavens and the earth. The earth was without form and void, and darkness was upon the face of the deep." (Earth's early atmosphere blocked the sunlight.)
Day one: "Let there be light." (As the atmosphere changed the sun's light began to shine through.)
Day two: God separates the waters above from the waters below. (The evaporation and rain cycle began.)
Day three: Dry land appears, then plants appear. (Land rose from the ocean, then plants appeared.)
Day four: Sun, moon and stars appear. (The changing atmosphere finally reveals the sun, moon and stars.)
Day five: Sea creatures (up to and including sea mammals), then birds, appear.
Day six: Animals (Ross says these are land mammals), then humans appear.
Dinosaurs: From Lab to Museum
1992 AD
LOS ANGELES, CALIFORNIA
Once a dinosaur has been removed from the ground, much work remains to be done.
In the laboratory the bones are unpacked from their protective coverings and cleaned. Scientists use microscopes and brushes and tiny tools, such as dental picks, to completely remove the soil surrounding the bones. They also make pictures of each of the pieces. The bone fragments are strengthened with liquid plastics and glued together. A favorite hardener is the acetone-based lacquer called "glyptol," which penetrates the fossil and then hardens. Elmer's Glue is the glue of choice. It can be easily softened with water and pulled apart for re-adjustment. The process of recreating a dinosaur skeleton can take years.
After scientists discover what the dinosaurs looked like, they can make molded copies of the bones to display in museums.
These reproductions are often arranged in a realistic fashion to show museum visitors what the dinosaurs looked like, how they acted, and what their environment was like.
0Brachiosaurus: Heavier Than 12 Elephants!
152 Million BC;75 Feet;89 Tons
TANZANIA, AFRICA
It is possible that no land animal, living or dead, was as massive as the giant plant-eating dinosaur Brachiosaurus. Measuring 75 feet in length, Brachiosaurus weighed close to 89 tons: eight times that of its close relative Diplodocus and 12 times that of a modern elephant!
These giants lived during the late Jurassic period and their skeletal remains have been found in Africa as well as North America.
Brachiosaurus' neck was so long that it made up almost half of its total height. By comparison, its head -- which measured three feet long -- was minuscule. The name Brachiosaurus means "arm reptile." It was given to the dinosaur because its front legs were much longer than its hind legs, a very unusual feature for most Sauropods. This had advantages, though. When combined with its enormous neck, Brachiosaurus could raise its head close to 45 feet, or as high as a three-story building. Brachiosaurus was once thought to spend most of its time underwater using the two nasal openings on the top of its head as snorkels. That theory has been rejected because the water pressure on its massive body would have made breathing almost impossible.
LOCALITY: Colorado, USA; Algeria, Tanzania, Africa
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Brachiosauridae
|Slow and Dumb, Fast and Smarter
Most people would agree with pioneer dinosaur hunter Othniel Marsh when he said that the size of Apatosaurus' brain showed it was a "stupid, slow-moving reptile."
It is probably true that Apatosaurus was a fairly dumb animal, especially when compared to birds and mammals of today. With a brain the size of a cat's it certainly couldn't beat you at a game of checkers, but Apatosaurus didn't need a lot of brain power to chew on plants.
The three-ton Stegosaurus didn't need much intelligence either. Its brain was about the size of a walnut, but it worked well enough to keep stegosaurs alive for more than 10 million years.
However, not all dinosaurs had brains quite so tiny. Scientists have found that dinosaurs that needed larger brains had them, though they were still small compared with those of mammals.
When the size of dinosaur brains have been compared to their body weight, it turns out that the big sauropods, like Apatosaurus, had small brains, only about one one-hundred-thousandth the weight of their bodies. Others, dinosaurs that lived in herds or hunted in packs, had larger brains, and clever solitary hunters had the largest brains of all.
Fast-footed Troodon, a Late Cretaceous dinosaur, may have been the smartest dinosaur of all. Its brain was about one one-thousandth the weight of its body. By comparison, your brain is about one-fortieth the weight of your body.
ΩApatosaurus: Swamp to Tree Top
143 Million BC;70 Feet;33 Tons
COLORADO, UNITED STATES
Scientists used to think that Apatosaurus (once known as Brontosaurus) was exclusively a swamp dweller.
They thought this huge animal -- the size of six elephants -- was far too heavy to support itself outside the water. The water, they said, would help keep the 33-ton giant from collapsing from its own weight.
But then they uncovered clean, sharp fossilized Brontosaurus tracks. The tracks were not in mud -- the kind of surface you would expect at the bottom of a river -- but in sand. Also, right next to them were the footprints of the deadly Allosaurus, which was undoubtedly a land-dwelling dinosaur. Unless the Allosaurus had been scuba diving, this meant Brontosaurus was perfectly able to get around on land.
Now scientists believe Brontosaurus was a land animal that grazed on leaves and branches from the tops of trees.
LOCALITY: Oklahoma, Utah, Wyoming, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Diplodocidae
nBuckland Names Megalosaurus
1824 AD
OXFORD, ENGLAND
The first dinosaur to be given a scientific name was Megalosaurus, whose bones were found by clergyman and Oxford University scientist William Buckland. The dinosaur was identified in 1824 from a jawbone with teeth, a portion of the hip, shoulder bones and some bones from the hind leg that Buckland decided belonged to a big meat-eating reptile.
2Camarasaurus: Did It Have a Trunk?
153 Million BC;60 Feet;20 Tons
UTAH, UNITED STATES
Camarasaurus, or "chambered reptile," roamed the moist, lush plains of North America during the late Jurassic period, feeding on the rich vegetation that covered the land. A fairly common long-necked plant eater, Camarasaurus probably traveled in herds that migrated from one feeding place to another.
Camarasaurus had a small head which was perched on top of an extra-long neck that enabled it to reach even the highest branches of trees in search of food. An adult Camarasaurus could grow to 59 feet in length and was very similar in build to its close relative, the Brachiosaurus, only much smaller.
An odd trait of Camarasaurus was its nostrils, which were placed high up on its head, just in front of the eyes. Scientists once thought that Camarasaurus may have lived mostly underwater with only its head poking out, using these nostrils to breathe. But that was thought unlikely considering the weight of the water pressure. More recently, some believe that Camarasaurus may have had a long trunk, like that of an elephant, which extended down from its nostrils. Others believe that Camarasaurus used its nostrils as a cooling device for the brain.
LOCALITY: Colorado, Oklahoma, Utah, Wyoming, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Camarasauridae
╖The Explosion Of Life
570 Million BC
EARTH
About 570 million years ago nothing much seemed to be happening on the earth's surface. The upper atmosphere was finally strong enough to keep oxygen created by algae from escaping into space. Volcanoes continued to erupt, but no longer with the same intensity.
Beneath the seas, however, a tremendous abundance of living creatures suddenly began to flourish. During this time, known as the Cambrian Period, the world's seas filled with corals, sponges and anemones. Ancient shellfish such as oysters, mussels and bivalves also began to cover the sea floor, while worms, jellyfish and primitive squids floated along the water's currents scooping up algae and other organisms for food.
┤The World's a Jungle
320 Million BC
EARTH
In the Carboniferous Period of 360 to 286 million years ago, large, swampy jungles like these spread across much of the earth. The planet's average temperature was much higher than it is today and the air was humid, making conditions perfect for plants to thrive.
Plants such as the giant club moss and horsetail fern grew increasingly large. They developed thicker trunks and reached heights of 70 and 80 feet. Also, the first trees, known as gymnosperms, began to appear. Gymnosperms are trees like the pine and the ginkgo, which have protected seeds.
At the same time, flying insects like giant dragonflies with two-foot wingspans darted between the vines and branches of the jungles. On the ground, a more interesting development was taking place. Scientists believe lobe-finned fish -- with their muscular fins and primitive lungs -- were becoming the first amphibians (animals that could spend time both in and out of the water).
ªAndrews' Dinosaur Treasure Trove
1922 AD
MONGOLIA
Roy Chapman Andrews went to Mongolia in 1922 hoping to find out something about the origin of man. He didn't find out anything about man, but he discovered a treasure trove of dinosaur bones.
During four expeditions to the Gobi Desert between 1922 and 1925, he discovered Protoceratops, a nest of Protoceratops eggs, Pinacosaurus, Saurornithoides, Oviraptor and Velociraptor, none of which were known before.
hChasmosaurus: Strong Jaws?
71 Million BC;17 Feet;2.5 Ton
ALBERTA, CANADA
Chasmosaurus, like its cousin Triceratops, had three horns on its head and a large shield covering its neck.
But instead of being solid bone, this shield had two very large holes in it. This has led many scientists to think that the large gaps in the neck-shield may have held powerful jaw muscles to help Chasmosaurus bite down on very tough plants.
Scientists have found impressions of Chasmosaurus' skin, so they know it was covered with large, round bumps.
LOCALITY: Alberta, Canada; New Mexico, USA
LENGTH: 17 Feet
ORDER: Ornithischia
SUBORDER: Ceratopsia
FAMILY: Ceratopsidae
5Chirostenotes: Slender Hand
80 Million BC;5 Feet;125 Pounds
ALBERTA, CANADA
What little we know of Chirostenotes -- which means "slender hand" -- is from two sharply clawed hands, the only two parts of this dinosaur that have been found. However, these hands resemble the hands of the dromaeosaurs, some of the fastest and meanest of the meat-eating dinosaurs. If this is true, it is quite possible that Chirostenotes hunted in packs and was capable of tracking and killing much larger dinosaurs.
LOCALITY: Alberta, Canada
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Oviraptorosauria
FAMILY: Caenagnathidae
The Slow Death Theory
50 Million BC
EARTH
One of the simplest theories of why the dinosaurs died out is that the earth's climate gradually changed. As the continents of the earth continued to shift 60 million years ago, new mountains rose and sea levels gradually dropped. As a result, the average air temperature around the earth could have fallen 17 degrees or more, changing weather patterns and giving rise to new kinds of plants. It's possible, think some scientists, that dinosaurs were not well adapted to such colder weather. If they were, indeed, cold-blooded animals, then the colder air temperature would have made them more sluggish and less able to hunt or forage for food.
Another possibility is that dinosaurs were not well suited to the new vegetation, such as flowering plants and leafy trees, which thrived in a cooler climate. Convincing as this theory sounds, it does not explain why dinosaurs did not simply move to the tropical regions of the world where the temperature is far warmer, or why dinosaur fossils have been found above what was then the Arctic Circle.
'Coelophysis: The Cannibal
220 Million BC;10 Feet;600 Pounds
NEW MEXICO, UNITED STATES
This small, compact dinosaur was built for speed and agility. While Coelophysis stood only about seven feet tall, its powerful rear legs and long slender body made it a fast and deadly predator. It had a long narrow head and a mouth filled with numerous razor-edged teeth. Unlike other dinosaurs, the leg bones of Coelophysis were nearly hollow, which helped reduce its total body weight and increase its speed.
In 1947, dozens of Coelophysis skeletons were found in a mass grave in New Mexico, which has led many scientists to believe that these dinosaurs hunted in large packs. Strangely, at the same location, some adult Coelophysises contained the skeletons of their young. At first this was thought to be proof that they may have given birth to live young rather than laying eggs like other dinosaurs. But now it is believed that Coelophysis was probably a cannibal that occasionally ate its own offspring.
LOCALITY: United States
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Coelurosauria
FAMILY: Coelophysidae
ñCompsognathus: The Bird's Ancestor?
148 Million BC; 2 Feet; 8 Pounds
KELHEIM, GERMANY
The smallest known dinosaur, Compsognathus, is believed by many scientists to be an early relative of Archaeopteryx, often considered to be the first bird.
Compsognathus, first found in Germany, was about the size of a house cat. It had long back legs, short arms and a long tail for balancing while running. Apparently Compsognathus liked to eat lizards, because a lizard skeleton was found in the abdominal cavity of a Compsognathus fossil.
One of the most interesting things about this creature is the debate about whether it is a predecessor of Archaeopteryx.
Supporting the theory is the fact that the bone structure of Compsognathus is quite similar to that of Archaeopteryx, and the two dinosaurs were about the same size. They also lived at the same time in history, which would have made it difficult for Compsognathus to be an ancestor. It is still possible, though, that Compsognathus lived earlier than Archaeoptyeryx.
On the other side of the argument, Compsognathus had hollow bones, like modern birds, but Archaeopteryx had solid bones. Another objection is that Compsognathus doesn't have a collar bone, and many scientists believe birds' wishbones must have evolved from an animal with a collarbone. But while Compsognathus didn't have a collar bone, perhaps one of its relatives did.
LOCALITY: Europe
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Coelurosauria
FAMILY: Compsognathidae
üMarsh and Cope: The Fossil War
1877 AD
NEW HAVEN, CONN.
In the 1870s, the intense rivalry between two Americans, O.C. Marsh, a professor at Yale, and E.D. Cope, a brilliant scientist from Philadelphia, led to some of the greatest dinosaur discoveries of all time.
The rivalry began in 1866 when Cope showed Marsh his study of an ancient skeleton found in Kansas. Upon closer inspection, Marsh discovered a big mistake in Cope's drawing. The head of the plesiosaur, an aquatic reptile, was placed on the wrong end of the skeleton. After Marsh published his findings, Cope was so upset that he tried to destroy every copy of the report before anyone could read it.
Ten years later, when fragments from a rich fossil deposit in Colorado were brought separately to each of the two men, they immediately headed out West determined to be the first to unearth the most spectacular dinosaur fossils. This period became known as the "great dinosaur rush" and led to some of the largest dinosaur discoveries in the world.
With money from their wealthy families, Marsh and Cope sent huge teams of explorers to Colorado, Wyoming and Montana on long, arduous fossil digs. Between 1877 and the late 1890s, the two men discovered nearly 130 new species of dinosaurs, including the well-known Brachiosaurus, Triceratops and Tyrannosaurus. Today, some of the largest, most breathtaking dinosaur displays in the world are the result of this intense rivalry.
╕Corythosaurus: Corinthian Helmet Reptile
90 Million BC;33 Feet;5 Tons
ALBERTA, CANADA
Corythosaurus is certainly called the "Corinthian helmet reptile" for a good reason. With its unique head crest, Corythosaurus is one of the best known of the duckbilled dinosaurs called hadrosaurs which inhabited the dense forests of what is now Montana and Canada at the end of the dinosaur age. Measuring 33 feet in length and weighing five tons, it was also one of the largest dinosaurs of its kind.
Of course, the most amazing feature of this massive plant-eater was the large, almost one-foot-high, hollow crest on the top of its head. Shaped like a large upright dinner plate, this crest spanned from the front of the dinosaur's forehead to the back of its skull. Like other crested duck-billed dinosaurs, Corythosaurus' crest was filled with nasal passages. It is still not entirely clear what these crests were used for and why some hadrosaurs had them while others did not.
The most popular theory held today is that the crest functioned as either a sounding device that enabled Corythosaurus to warn others of danger or as an enlarged sensory area which increased the creature's sense of smell. Another possibility is that the crest was used for cooling the animal under the hot sun. Other scientists believe the crest may have been brightly colored to attract a mate, or so one Corythosaurus could recognize another.
LOCALITY: Alberta, Canada; Montana, USA
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Lambeosauridae
Cretaceous: The Continents Split
144-65 Million BC
EARTH
Both giant continents, Laurasia and Gondwana, began splitting during the Cretaceous Period. Mountains began growing and the seasons became more pronounced. Flowering plants spread and by the end of the Cretaceous period, oak trees, hickories, and magnolias were common in North America. The forests began to look almost modern.
During this time toothless, bird-like dinosaurs appeared, as did the greatest of the meat-eaters, Tyrannosaurus. But the meat-eaters were matched by heavily armored plant-eaters, such as Triceratops and Ankylosaurus. Duck-billed dinosaurs with mouths designed for eating tough plants were common.
Large flying reptiles and waterbirds soared above the earth and there were many animals that are with us today: lizards, snakes, frogs, salamanders, and small mammals like possums could all be found.
Then, 65 million years ago, it all came to an end. The dinosaurs died out completely and quickly, perhaps due to comets or a meteor striking the earth, or perhaps due to climate changes.
uDeinosuchus: Big As a Dinosaur
230 Million BC;49 Feet;4.5 Tons
TEXAS, UNITED STATES
The first primitive crocodile appeared on the earth 230 million years ago, during the Mid-Triassic Period, about the same time the first dinosaur appeared. Interestingly, both dinosaurs and crocodiles are from the same group of reptiles known as "archosaurs" or "ruling reptiles." But somehow, crocodiles survived while dinosaurs did not.
Originally, many crocodiles probably spent their time on land hunting for insects or small animals. Over time, however, they became the semi-aquatic animal we know today.
One ancient crocodile named Deinosuchus, however, was quite unique. Only the skull of Deinosuchus has been found and it measured an unbelievable six feet six inches long. If Deinosuchus was built the same way modern crocodiles are built, then its body would have been 50 feet long. With its massive jaw, Deinosuchus would have been one of the most ferocious meat-eaters alive at the time. Lying hidden in the swamps, Deinosuchus could have seized even medium-sized dinosaurs with a single snap of its enormous jaws.
LOCALITY: Texas, USA
ORDER: Crocodylia
SUBORDER: Eusuchia
FAMILY: Crocodylidae
ƒFirst Dinosaur Park
1854 AD
LONDON, ENGLAND
After the Great Exhibition of the Works of Industry of All Nations held at Hyde Park, London, in 1851, a large steel, glass and wood building called the Crystal Palace was moved to Sydenham Park (now Crystal Palace Park) in southeast London. Dinosaur scholar Richard Owen was asked to provide life-sized models of dinosaurs for the grounds of the park.
Together with sculptor Waterhouse Hawkins, they made several dinosaurs. Just before they finished in 1854, they held a party for 20 guests inside the nearly complete body of an Iguanodon model.
The Crystal Palace burned down, but Owen's models (though now known to be incorrect) are still there.
gFather of Palaeontology
1770 AD
PARIS, FRANCE
Georges Cuvier knew more about old bones than anybody of his time. In fact, he is called the father of palaeontology. But when he saw a giant tooth sent to him by Gideon Mantell, he thought it belonged to an extinct rhinoceros. Later, he admitted his error and correctly predicted that the Iguanodon tooth meant scientists would soon discover a whole new group of animals.
On the other hand, Cuvier correctly identified a huge jaw bone brought out of a chalk mine in Holland as belonging to a giant marine reptile called Mosasaurus.
Cuvier believed there had been repeated extinctions of life forms throughout history, a view that was later rejected, but today has been largely accepted again.
He was also convinced that evolution had not occurred. He said each species is so well developed that it would not be able to survive any serious changes.
Charles Darwin's Revolution
1859 AD
GALAPAGOS ISLANDS
Charles Darwin was a little unsure. Was he ready to publish his findings? Twenty-two years earlier, in 1836, he had returned to England with the germ of a radical new idea about the origin of life.
On the Galapagos Islands near South America, Darwin had seen animals that were related -- but different. Perhaps, he thought, the mechanism that caused these slight variations could also cause major changes in plant and animal life. He theorized that in the battle to live, plants and animals most adapted to their environment would survive and pass on the survival traits to their offspring. Eons of little adaptations, he thought, could result in completely different species.
His evidence clearly showed that small evolutionary changes do occur, but his evidence for big changes was more speculative. But on the other hand, Darwin knew other biologists were working on the same idea, so he finally sat down and wrote "The Origin of Species."
It came out in 1859 and caused a furor since most people believed God created the plants and animals. Critics challenged him on the "infinitude of connecting links" he had predicted must exist. "Where are these links?" they asked.
The uproar died down as most scientists and others accepted Darwin's theory.
ßMeteor vs. Dinosaurs
65 Million BC
YUCATAN, MEXICO
Could the impact of a giant meteor striking the earth have caused the sudden extinction of the dinosaurs? Some scientists think so.
Meteorites, which are pieces of rocks from space, have always collided with the earth. Enormous craters like the one in this picture are proof that very large meteors have indeed struck the earth in the distant past.
It's very possible, think some, that a massive meteor measuring six to nine miles wide may have hit the planet sometime at the end of the Cretaceous Period. The force of the impact from such a meteor would have created a crater nearly 100 miles wide. It also would have made an enormous explosion, sending huge amounts of dust and debris into the atmosphere. In a very short time, the skies around the world would have been covered by a blanket of dust, blotting out much of the sun's rays. This could have lasted for several months or even years.
Without much sunlight, the temperature around the earth would have quickly dropped below freezing, killing plants as well as animals. If enough plants were killed, then the food for many dinosaurs would have disappeared.
The crater left by such a meteor must be huge. If so, where is it? There's a giant crater on the Yucatan peninsula of Mexico and the Gulf of Mexico that seems about the right size. Though most visible traces of it are gone, it has been measured at 110 to 185 miles in diameter, which means the meteor that struck there must have been five to 10 miles across.
ùDeinonychus: Small But Deadly
130 Million BC;7-10 Feet;175 Pounds
MONTANA, UNITED STATES
Deinonychus was not very large, but it certainly was deadly. Some think that Deinonychus was one of the most ferocious dinosaurs ever. And that is easy to believe after seeing this movie!
Measuring only seven to ten feet long, these small, fast-moving predators could bring down dinosaurs many times their size. Scientists believe Deinonychus hunted in packs, which would surround and overpower large dinosaurs such as slow-moving
plant-eaters. Deinonychus was well-adapted for hunting. It had fast, powerful thighs and a large head with sharp teeth that were perfect for biting off pieces of flesh and holding small prey in its mouth.
Deinonychus' unique trait, however, was a single large, curved claw found on both of its feet. When Deinonychus was walking or running, the claw was pulled back so it wouldn't interfere with the dinosaur's movement. But when Deinonychus was
attacking, the claw was lowered so it could be used as a sharp weapon. Deinonychus likely grabbed its prey with its mouth and hands and tore at its victim's underbelly.
To maintain its very high level of activity, some scientists believe that Deinonychus had to have been a warm-blooded animal. They say that a cold-blooded animal would have been too sluggish for Deinonychus' active lifestyle.
LOCALITY: Western USA
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Deinonychosauria
FAMILY: Dromaeosauridae
lPlants Invade the Land
400 Million BC
EARTH
About 400 million years ago the surface of the earth went through dramatic changes. The collision of the planet's shifting continents created large ranges of mountains which helped to raise the level of the land. As the water fell in many places the first plants began to invade the land. These were close relatives to seaweed and other ocean-going plant life. Without water surrounding them, however, these plants developed roots to absorb moisture from the ground, stems for support and a tough texture for their leaves in order to keep from drying out. The most primitive land plants were very small and mossy and stayed close to the shores of seas or lakes.
Sometime in the middle of the Devonian Period, about 345 to 400 million years ago, the first ferns appeared, initially without leaves and seeds. Gradually, these ferns developed leaves and very strong stems with some growing as tall as trees.
At the water's edge, something more amazing was taking place. Crabs, spiders, mites and other non-flying insects began to emerge. They thrived in the swampy jungles that were spreading across the earth's landscape.
╤ Dimetrodon: Sharp Teeth
270 Million BC;10 Feet;250 Pounds
NORTH AMERICA
You can see in this movie that Dimetrodon had sharp teeth. Judging from their shape and from the fact that Dimetrodon lived near the sea, scientists think he probably used them to catch fish.
Dimetrodon: Sailor, or Solar?
270 Million BC;10 Feet;250 Pounds
NORTH AMERICA
How do you think Dimetrodon (a reptile, but not a dinosaur) used this strange sail on its back?
Believe it or not, for a while some scientists thought it was actually for sailing, allowing Dimetrodon to sail across the water in search of food.
Dimetrodon, which literally means "two long teeth," had sharp teeth that look as if they would be good for eating fish, and Dimetrodon fossils have been found near ancient lake sites, so it seems reasonable to think that this creature ate fish, though it is also possible it ate other animals as well.
However, scientists no longer believe that the sail on its back had anything to do with sailing. Instead, they think that Dimetrodon could face the sail toward the sun to warm itself quickly, or turn the edge of the sail toward the sun to cool itself. Also, the sail may have been brightly colored and used to frighten rivals or predators, as well as to attract mates.
LOCALITY: North America
CLASS: Reptilia
SUBCLASS: Synapsida
ORDER: Pelycosauria
FAMILY: Sphenacodontidae
,What Killed the Dinosaurs?
65 Million BC
BERKELEY, CALIFORNIA
Why did the dinosaurs die? One theory is that a giant meteor or swarm of comets hit the earth and killed them all.
Nobel-Prize-winning scientist Luis Alvarez, a leading supporter of that theory, noted that throughout the world a metal called iridium suddenly appeared in the layer of rocks that were formed about the time dinosaurs died.
Iridium is rare on earth but fairly common in space. Maybe something from space hit earth.
If so, it would have had to be at least six miles in diameter, about the size of Mount Everest. If such a meteor hit Earth at 90,000 miles an hour, the sky would have been filled with dust and the sun would have been very dim.
Without enough sunlight, plants would die, and then the animals would starve to death.
Perhaps all life didn't die because some seeds remained in the ground, waiting for the Sun to return. Possibly some animals lived by eating the carcasses of other creatures.
The crater left by such a meteor must be huge. If so, where is it? There's the giant Chicxulub crater on the Yucatan peninsula of Mexico and the Gulf of Mexico that seems about the right size. Though most visible traces of it are gone, it has been measured at 110 to 185 miles in diameter, which means the meteor that struck there must have been five to 10 miles across.
Sauropods Vs. Predators
70 Million BC
ALBERTA, CANADA
If you get the feeling that this giant Brachiosaurus is not going to get the worst of its fight against the meat-eating Ceratosaur, you are probably right. The largest of the plant-eating dinosaurs probably had little to fear from meat-eaters. Some scientists believe these giants could even rise up on their rear feet and come down hard on a pesky predator. It was also quite likely that a brachiosaurus could use its immense tail like a whip, knocking down large meat-eaters with a single blow.
ôDiplodocus: Light As A Feather?
156 Million BC;100 Feet;11 Tons
UTAH, UNITED STATES
Diplodocus was an enormous dinosaur that grew as long as 100 feet. But most of this length was taken up by its incredibly long neck and even longer tail. In fact, Diplodocus' body accounted for only about 13 feet of its entire length, while its tiny head measured a relatively small two feet.
Diplodocus lived during the Late Jurassic Period and probably traveled in herds around what is now Colorado, Montana and Wyoming, feeding on the lush vegetation that thrived at the time. Though Diplodocus was a huge animal, it only weighed 11 tons, about one-eighth the weight of its 75-foot long cousin Brachiosaurus. Diplodocus was much lighter than other large plant-eating Sauropods because its bones were hollow.
Some scientists, but not all, believe that when Diplodocus was hungry it could stand up on its rear legs and, using its huge tail for balance, stretch to nearly 50 feet above the ground in order to feed on the very tops of trees -- about 29 feet higher than today's giraffe can reach!
LOCALITY: Colorado, Montana, Wyoming and Utah, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Diplodocidae
÷Dilophosaurus: The First Terror
203 Million BC;20 Feet;1000 Pounds
ARIZONA, UNITED STATES
One of the first terrible meat-eaters was Dilophosaurus, first found in Arizona.
Generally, Dilophosaurus resembled other meat eaters. It was fast and agile, ran on two feet, had a long tail and sharp teeth. But there were some odd aspects to it.
On the top of its head -- from the front of its snout to a point between its eyes -- ran two bony crests. The crests were quite thin, so it is unlikely they were used in combat. Scientists don't really know what they were for, but they may have been used as a sexual signal to females, or to make their heads look bigger and frighten other animals.
Also, Dilophosaurus' teeth were long and slender and its jaws were not as strong as other big meat-eaters. This has led scientists to think that they may have slashed repeatedly at their prey rather than killing them with a few bites. Or, perhaps they were scavengers.
LOCALITY: Arizona, USA
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Megalosauridae
¿The Little Plan of Life
1953 AD
CAMBRIDGE, ENGLAND
From dinosaurs to you, there is an amazing little set of plans for every living thing. It's a chemical called DNA.
DNA, which stands for deoxyribonucleic acid, comes in long strands that inhabit the nucleus of every living cell. Human DNA, for example, is made up of about three billion steps.
Although DNA is often called the blueprint for life -- because it is like plans from which a building is made -- it's more like a very complicated computer program. Computer programs consist of line after line of simple statements: move X to Y, subtract T from Z, jump to line 17. DNA is just like this. Each stair step is a line in the code.
DNA is such an amazingly compact information storage system that all the designs for every living thing that has ever existed on earth plus all the information in every book ever published would fit in a teaspoon. In some cases the same string of DNA can even contain different information. It is as if a sentence reads differently depending on which letter you begin on.
English physicist Francis Harry Compton Crick and American biochemist James Dewey Watson won the Nobel Prize for discovering the basic structure of DNA.
eEarth On The Move
400 Million BC
EARTH
Ever since the earth's formation 4.6 billion years ago, the surface of the planet has not stopped moving. That's hard to believe when you consider how enormous the earth's continents and oceans are. Yet, beneath the surface of the planet lie massive plates of rock which move ever so slowly over the earth's molten core. As these plates move, they carry the continents with them, sometimes in very different directions. This is what scientists call "continental drift." Over hundreds of millions of years, the slow movement of these plates has caused the earth's continents to gradually shift their positions all over the planet.
Of course, this movement is so slow that it is almost impossible to detect except with the most precise scientific instruments. However, it is possible to see the effects of these shifting plates all around us. For instance, when plates collide into one another or grind past each other they push up layers of rock and earth on the planet's surface, creating mountains. Other times, the friction of two plates rubbing against one another can cause an earthquake. The large earthquakes that frequently strike California are the result of two enormous plates grinding against each other. Eventually, it is said, Southern California will slide so far to the northwest that it will become an island or peninsula near the San Francisco Bay area.
σEarth As We Know It
50 Million BC
EARTH
Just as the dinosaurs began to vanish from the earth, the modern continents had finally begun to take shape. Australia and Antarctica had broken off of South America. India had moved north until it pressed into Asia, forming the Himalayan mountain range. North America, South America and Europe had begun to take up their positions on either side of the globe. With the continents separated now, the plant and animal life began to develop very differently from place to place.
≥Dryosaurus: Oak Reptile
170 Million BC;13 Feet;545 Pounds
ROMANIA
Dryosaurus was a two-legged, plant-eating dinosaur with narrow eyes, a stiff tail, and strong legs to run from meat-eaters. To gather food it had five-fingered hands on long arms, a beak, grinding teeth and possibly large cheeks to help it hold its food in place while chewing.
Fossils of Dryosaurus, which means "oak reptile," have been found in Romania, England, Tanzania and the United States.
LOCALITY: Romania
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Dryosauridae
ZEdmontosaurus: 1001 Teeth
75 Million BC;43 Feet;2.9-3.9 Tons
MONTANA, UNITED STATES
Edmontosaurus was one of the largest of the duckbilled hadrosaurs which foraged for plants in the ancient forests of what is now western North America. This 43-foot long dinosaur had a broad, flat snout with a horny covering, and a large, toothless beak that looked very much like a duck's bill. While its bill was quite toothless, Edmontosaurus' inner jaw contained many banks of teeth. These teeth were perfect for grinding up plants and tough vegetation. As soon as they wore down, new teeth would grow quickly in their place. Edmontosaurus probably had more than 1,000 teeth in its mouth at any given time.
Edmontosaurus' jaw was similar to that of Iguanodon. Both dinosaurs could move their jaws from side to side, making it much easier to grind and pulverize the fibrous plants that made up their diets.
One of the stranger features of Edmontosaurus was its huge nostrils. Paleontologists believe these nostrils could have been covered with large flaps of loose skin. This skin could have been inflatable, allowing Edmontosaurus to make loud, bellowing noises. These inflatable nostrils could also have been brightly colored and used during mating season, or as a way for individual Edmontosaurus' to recognize each other.
LOCALITY: Alberta, Canada; Montana, USA
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hadrosauridae
íElasmosaurus: Longest Marine Reptile
93 Million BC;46 Feet;3.7 Tons
KANSAS, UNITED STATES
Measuring 46 feet in length, Elasmosaurus was the longest known plesiosaur, or marine reptile, to roam the seas of the Cretaceous era. Elasmosaurus' neck alone measured close to 26 feet, more than half its body length! This snake-like neck was made up of more than 71 vertebrae and was three times longer than that of any of its near relatives.
The rest of Elasmosaurus' body was sturdy and compact. Its tail was short, and its huge, paddle-like flippers were perfect for propelling Elasmosaurus through the water, much like a sea turtle does. Scientists think that Elasmosaurus spent much of its time swimming with its head just above water, scanning the waves for small fish and squid to eat. Like Plesiosaurus, Elasmosaurus probably only left the water to lay its eggs in the sand.
LOCALITY: Kansas, USA; Japan
CLASS: Reptilia
SUBCLASS: Unknown
ORDER: Plesiosauria
FAMILY: Elasmosauridae
£Estemmenosuchus: Mammal-Reptile
250 Million BC;13 Feet;355 Pounds
RUSSIA
This mammal-like reptile, called Estemmenosuchus, lived in the Permian Period, just before the Triassic, when the dinosaurs appeared.
Estemmenosuchus means "strong garment reptile." It had large, sharp, front teeth but tiny side teeth, suggesting it ate plants. Its skull, about 36 inches long, was heavy and had bony lumps on its forehead and snout, perhaps for fighting other male Estemmenosuchus.
Euoplocephalus: All Secure
95 Million BC;18 Feet;2 Tons
ALBERTA, CANADA
With all of its heavy armor and thick bones, Euoplocephalus seems like it would be slow and clumsy. Quite the contrary. Because its armor plating developed in narrow bands, Euoplocephalus was quite agile for a dinosaur of its size and mass.
Living up to the end of the Cretaceous Period, Euoplocephalus was one of the largest of the armored dinosaurs known as ankylosaurs. It weighed close to two tons and measured 18 feet in length. Bands of armor were embedded in its back and covered with large, bony knobs. There were also pointed spikes at the back of its head, over its shoulders and at the base of its tail. Like its close relative Ankylosaurus, even its eyelids were armored with bony plates that slid down to protect the eye socket when the dinosaur was in combat.
In combat, Euoplocephalus must have been quite a fighter. Even its natural enemy, the powerful Tyrannosaurus, would have had a tough time breaking through Euoplocephalus' heavy body armor. Meanwhile, Euoplocephalus would try to scramble around until it could swing the massive bony club at the end of its tail toward Tyrannosaurus' legs and stomach. A direct hit might have been fatal.
LOCALITY: Alberta, Canada
ORDER: Ornithischia
SUBORDER: Ankylosauria
FAMILY: Ankylosauridae
ΩEuparkeria: The Ancestor?
245 Million BC;2 Feet;30 Pounds
SOUTH AFRICA
Euparkeria, a small, lightly built reptile, is of interest to scientists because it may be the ancestor to both the dinosaurs and crocodiles. This is not certain, though, because the ankles, which would give the best evidence, are not well preserved.
This little meat-eater, just two feet long, probably walked on all four feet most of the time, then got up on its two powerful back feet to run when it needed to escape danger. It had a long tail, about half as long as its body, and bony plates down the middle of its back and tail.
Euparkeria means "good Parkers" after British scientist W. K. Parker.
LOCALITY: South Africa
SUPERORDER: Archosauria
ORDER: Thecondontia
SUBORDER: Ornithosuchia
FAMILY: Euparkeriidae
FMonkeys and Typewriters
1859 AD
LONDON, ENGLAND
Darwin's theory of evolution has a simplicity that is appealing. One of his contemporaries summarized it in a single phrase: Evolution, he said, is the "survival of the fittest."
The theory is widely accepted by scientists today. However, some people object to evolution on religious grounds, and some on scientific grounds.
Though it is the minority view in scientific circles, critics of evolution raise some interesting points. Here are a few:
-- It is difficult (some believe to the point of impossibility) for life to arise from non-life, even if all necessary ingredients were mixed in abundance.
Though some doubt he meant it, Darwin apparently did not believe life developed from non-life. He attributed the first living thing to a "Creator." Nevertheless, life developing from non-life has become part of evolutionary theory.
English scientist Thomas Huxley suggested time and chance caused the first life. He reportedly said six monkeys typing mindlessly for millions of years could write all the books in the British Museum. By the same random method, he said, simple life could be created.
But in his recent book, "The Philosophical Scientists," British scientist David Foster says this is unlikely: "Allowing Huxley all the monkeys there have ever been, typing for all the time there has ever been, there would be a shortfall ratio of more than one hundred million millions, and that only relates to the chance of typing one line of one book in the British Museum."
-- That evolution causes minor changes is virtually beyond dispute, but some scientists (including Darwin's contemporary, French anatomist Georges Cuvier) don't believe it can cause major changes. This is because living beings are complex mechanisms and a change to one part of the mechanism affects other parts.
Compare life to an automobile. You can change the paint or flare the fenders (somewhat) without problem, but, for example, if you change the size of a piston, even a bit, other parts of the engine must be changed to accommodate it. That such coordinated changes should take place by chance at the same time in the same living being strikes some as extremely unlikely.
-- Darwin said occasional small changes make some animals better able to survive. Conversely, detrimental changes make them less likely to survive. But some anatomical changes would appear detrimental unless in fully functioning form.
Consider the bat, whose wing bones are, essentially, its fingers. If bats evolved from non-flying creatures, wouldn't the increasing length of these animals' fingers make them very clumsy and likely to be somebody's lunch long before the fingers became wings?
-- The fossil record doesn't show gradual changes. Darwin said big biological changes result from eons of little changes. Some in his day, such as anatomist Sir Richard Owen (who coined the word "dinosaur"), said the fossils didn't show little changes adding up to big changes. Many believed more study would close these gaps, but it hasn't.
Some scientists have proposed a theory called "punctuated evolution," in which species remain stable for ages, then isolated groups rapidly change from environmental pressure. Rapid change means there would be few intermediate species, which would explain the gaps in the fossil record. However, it also requires squeezing a vast number of changes into a relatively short time, which strikes some, including traditional Darwinists, as unlikely. -- Studies show that life forms that look similar are often genetically similar; apes and humans, for example. However, critics say, genetic material does not show the progression that evolution demands.
For example, most scientists believe jawless fish evolved into bony fish, which evolved into amphibians, then to reptiles and finally to mammals. This means genetic material should become increasingly different as you move from jawless fish to mammals. But it doesn't. In fact the genetic material of bony fish, amphibians, reptiles and mammals is about equally different from jawless fish -- and from each other.
For animals that evolved away from each other rapidly at some point in the very distant past, however, current genetic sequencing techniques may not be sensitive enough to detect these differences.
While the critics of evolution hold a minority view, their objections suggest that the question is not fully resolved.
CFrom Dust Cloud to Our House
4.6 Billion BC
EARTH
Way out in the boondocks of the Milky Way Galaxy about 4.6 billion years ago, a cloud of gas and dust began to come together into a rotating disk, attracted by its own gravity.
As this disk formed, gravity squeezed a large lump of gas at the center so hard that the hydrogen atoms began to fuse together, creating a nuclear reaction and igniting the fires of our sun.
Orbiting the sun, other clumps formed, eventually becoming planets, one of them the Earth. Those close to the sun -- Mercury, Venus, Earth and Mars -- became small and rocky planets. Those farther away mostly became large gas-covered planets: Jupiter, Saturn, Uranus and Neptune.
When Earth was first formed, you couldn't have lived on it. It was extremely hot and there was no oxygen to breathe. It took a long time for our planet to be ready for plants, animals and people.
Though Earth was once very hot on its surface, today it has cooled. But the natural radioactivity of rocks keeps the inside of our planet hot. Large sections of the Earth's surface drift around slowly, as you see illustrated here.
YLife: How Did It Happen?
4 Billion BC
EARTH
Here you can see an outline of the history of the Universe. In the sky are galaxies, and the comets, planets and moons that formed in the solar system, plus, of course, the Sun, on which all life depends.
In the ocean at the far left are the molecules that make up life. As you look to the right you can see the bacteria that were the first cells of life, followed by more complex sea life and, finally, land life.
This is the story science tells us, but how did it happen?
Many scientists believe that by chance molecules combined into simple life forms, and experiments have shown that with the right atmosphere, lightning and solar radiation could create simple amino acids that are the building blocks of life. Then these amino acids could combine into simple life forms, and these, in turn, could change into increasingly complex life forms by the process of evolution outlined by naturalist Charles Darwin.
Some scientists, however, don't believe this. They think that early life may have come from outer space.
Why?
Because -- in the words of scientists Francis Graham-Smith and Bernard Lovell -- the possibility of molecules randomly combining into life within no more than a billion years is "vanishingly small." Therefore, some scientists, such as geneticist Francis Crick, have concluded that early life must have come from outer space.
░Universe at a Glance
15 Billion BC
UNIVERSE
In this artist's illustration you can follow scientists' current understanding of the steps that occurred in the formation of the universe.
At the far left is the Big Bang, the explosion that marked the beginning of the universe. Why the bang occurred and where the material came from that exploded is still unexplained by science, but what follows is more clear.
To the right of the Big Bang you can see the great stretches of hydrogen that made up the early universe, and following it, the condensation of hydrogen into large clouds, and then into an early star, one of billions.
In the next image you can see our solar system begin forming, and then, finally, Earth.
5Ankylosaurs: Dinosaur Tanks
75 Million BC;33 Feet;4 Tons
ANTARCTICA
The ankylosaurs were the armored tanks of the dinosaur age. Even more than their cousins the nodosaurs, they were extremely well protected. They had heavy bone plates and spikes on their backs and their heads were covered by thick bony plates. Most ankylosaurs even had armor plating on their eyelids. With all of this armor, ankylosaurs were quite heavy. Some, like the ankylosaurus, probably weighed as much as four to five tons. At the end of their tails was a fearsome knot of bone they could swing like a club at a predator.
These dinosaurs lived in North America, East Asia, and have even been found in Antarctica.
LOCALITY: Antarctica, East Asia, North America
ORDER: Ornithischia
SUBORDER: Ankylosauria
FAMILY: Ankylosauridae
GENERA: Ankylosaurus
Euoplocephalus
Saichania
Talarurus
OCarnosaurs: The Meat Eaters
157 Million BC;25-40 Feet
NORTH AMERICA
Carnosaurs, meaning flesh lizards, were the kings of the dinosaur world. They had large, powerful back legs, small front arms, but fearsome claws and teeth. These dinosaurs were probably not unlike the predators we are familiar with today, such as lions and leopards. They probably hunted by themselves, preying on groups of smaller reptiles such as herds of herbivore. Their favorite prey was most likely weak or slow members of a herd. It is widely believed that some carnosaurs hunted in packs. In this fashion it was possible for smaller carnosaurs to attack and kill much larger dinosaurs such as the enormous plant-eating sauropods.
The carnosaur classification does not necessarily indicate these animals were closely related, but rather that they shared many similar features.
LOCALITY: North America, Africa, China
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILIES: Megalosauridae
Torvosauridae
Allosauridae
Abelisauridae
Ceratosauridae
Baryonychidae
Spinosauridae
Dryptosauridae
Tyrannosauridae
Aublysodontidae
Itemiridae
·Ceratopids: Armed and Peaceful
67 Million BC;6 to 30 Feet
NORTH AMERICA
Ceratopids were heavy four-footed animals with large, heavily armored heads, often with horns. The armor around their heads usually extended to cover their necks as well and was so thick that only the hardest blow could have any effect on these enormous dinosaurs.
The ceratopids lived for about 20 million years at the end of the Cretaceous period, probably roaming in herds and eating even the toughest vegetation with their powerful beak-like jaws. Physically, they are remarkably similar to today's rhinoceros, and many scientists believe that they moved and behaved like them as well.
When threatened, a herd of ceratopids may have faced outwards to present a meat-eating dinosaur with a wall of dangerous spikes.
LOCALITY: Asia, North America
ORDER: Ornithischia
SUBORDER: Ceratopsia
FAMILY: Ceratopsidae
GENERA: Anchieceratops
Arrhinoceratops
Centrosaurus
Ceratops
Chasmosaurus
Monoclonius
Pachyrhinosaurus
Pentaceratops
Styracosaurus
Triceratops
Torosaurus
ΣCoelurosaurs: Little Meat Eaters
220 Million BC;8 Feet
WYOMING, UNITED STATES
The Coelurosaurs were little, two-legged meat-eating dinosaurs. Their name means "hollow-tailed reptile."
This classification, which is one of convenience since Coelurosaurs were not all related, includes the little Compsognathus, Ornitholestes and Coelophysis.
LOCALITY: Europe, North America, Asia, Africa
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Coelurosauria
FAMILIES: Podokesauridae
Coeluridae
Compsognathidae
Ornithomimidae
RDiplodocid: Large but light
164 Million BC;90 Feet
NORTH AMERICA
Some of the biggest and best known of the dinosaurs belonged to the diplodocid family. These dinosaurs had tapering heads, pencil-like teeth, and nostrils on the top, rather than on the front, of their heads. While the diplodocids were enormous, they were not nearly as heavy as other large sauropods such as Brachiosaurus. This was made possible by the way in which the giant bones of diplodocids were hollowed out and made quite light for their size.
The diplodocids included Diplodocus, Apatosaurus, Supersaurus and Seismosaurus. They lived mostly in North America, but also in Europe, Asia and Africa.
LOCALITY: Colorado, Montana, Utah and Wyoming, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Diplodocidae
GENERA: Apatosaurus
Barosaurus
Diplodicus
Supersaurus
Seismosaurus
WDromaeosaurs: Fast and Mean
147Million BC; 13 Feet
CENTRAL ASIA
Among the fastest and meanest of the meat eaters were the dromaeosaurs.
These killing machines had a long head, sharp eyes, and a large brain for their size. Their front arms were also quite long for their body and their three fingers had sharp, curved claws. On their back feet the dromaeosaurs had a slashing toe that they held away from the ground when they were walking or running.However, when they were attacking their prey they used it to cut into their victims like a giant machete. Though dromaeosaurs were ferocious enough by themselves, it is possible they worked together in a pack to bring down larger animals.
LOCALITY: Alberta, Canada; Central Asia
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Deinonychosauria
FAMILY: Dromaeosauridae
GENERA: Deinonychus
Dromaeosaurus
Saurornitholestes
Velociraptor
£Hadrosaurids: The Most Common Dinosaur
100 Million BC;49 Feet
SOUTH AMERICA
Hadrosaurids were among the most common dinosaurs. They have been found all across the northern hemisphere, and even in a few locations in South America.
Hadrosaurids were plant eating dinosaurs. They all had long faces and flattened snouts that looked like ducks' bills, so they are often called duckbilled dinosaurs. The fronts of their mouths had no teeth, but they had plenty of teeth inside their mouths. The hadrosaurids used these teeth to grind up tough plants and vegetation. As their teeth wore down, they would be replaced with new ones.
Hadrosaurids probably walked on all four legs when they were eating, then rose up on their long back legs to escape from meat eaters.
LOCALITY: Worldwide
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hadrosauridae
GENERA: Brachylophosaurus
Edmontosaurus
Kritosaurus
Hadrosaurus
Maiasaura
Prosaurolophus
Trachodon
Tsintaosaurus
╬Hypsilophodontids: No dentist needed
160 Million BC;8 Feet
NORTH AMERICA
Hypsilophodontids were members of a very successful dinosaur family. They had large eyes, cheeks to hold food as they chewed, and teeth that sharpened themselves and replaced themselves as they wore out. They had five fingers on their hands and four toes on their feet.
Judging from their long, strong back legs, these two-legged dinosaurs were very speedy. Hypsilophodontids were herbivores and are believed to have been the ancestors of the Iguanodonts and the Hadrosaurs. They replaced the Fabrosaurs, which became extinct near the end of the Jurassic period. Nests of Hypsilophodontid eggs have been discovered with indications that the young stayed by the nest and were cared for by their parents. Hypsilophodontids were herd animals, much like the modern gazelle.
LOCALITY: Europe, North America
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hypsilophodontidae
GENERA: Hypsilophodon
Orodromeus
Othnielia
Rhabdodon
Tenontosaurus
FIguanodontids: Slow Movers
147 Million BC;29 Feet;5 Tons
ENGLAND
Members of the iguanodontid family were heavily built plant-eating dinosaurs. They had long heads with toothless beaks for clipping plants, and rows of teeth for grinding plants.
They were heavily built so in most cases they probably walked on all four feet, though they could rear up to reach food or defend themselves. They probably moved slowly since the bones of their upper legs are longer than the bones of their lower legs, just the opposite of fast moving animals.
On their front feet they had big spikes that would have been good for fighting off rivals or hungry meat-eaters.
LOCALITY: Africa, Asia, Australia, Europe, North America
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Iguanodontidae
GENERA: Anoplosaurus
Crasperdodon
Iguanodon
Ouranosaurus
Probactrosaurus
Vectisaurus
Lambeosaurids: Hollow heads
98 Million BC;49 Feet
COLORADO, USA
Lambeosaurids were duckbilled dinosaurs with a curious feature other duckbills did not have.
On their heads were all different shapes of hollow crests and bumps and horns. The lambeosaurs could breathe through these long nasal passages, and perhaps could signal to one another by blowing through them like a trumpet. Some scientists have suggested that they were also good for attracting a mate. Lambeosaurids probably travelled in herds, living in swampy wetlands that covered much of what is now North America.
LOCALITY: North America, Asia
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Lambeosauridae
GENERA: Bactrosaurus
Barsboldia
Corythosaurus
Hypacrosaurus
Jaxartosaurus
Lambeosaurus
Nipponosaurus
Parasaurolophus
mNodosaurids: Bumpy Dinosaurs
154 Million BC
NORTH AMERICA
The Nodosaurid family lived throughout the end of the Jurassic period and throughout the Cretaceous period. These dinosaurs were four-legged plant eaters with bony nodes covering their skin and spikes coming out of their sides. They had narrow heads, leaf-shaped teeth and a strong, hard beak. If a meat eater came along, they probably protected themselves by crouching close to the ground.
LOCALITY: North America, Europe
ORDER: Ornithischia
SUBORDER: Ankylosauria
FAMILY: Nodosauridae
GENERA: Hylaeosaurus
Panoplosaurus
Nodosaurus
Polacanthus
Sauropelta
Silvisaurus
Struthiosaurus
`Ornithomimosaurs: The Ostrich Dinosaurs
155 Million BC; 12 Feet
ALBERTA, CANADA
Some dinosaurs looked quite similar to modern-day ostriches. These ornithomimosaurs were fast dinosaurs with a large brain, large eyes, a narrow toothless beak and long legs. But unlike the ostrich, they also had short arms. Ornithomimosaurs probably ran exactly like ostriches, taking long, powerful strides on their two hind legs.
It is thought that these bird-like dinosaurs ate shrimp and crabs and other shellfish, or maybe insects, small animals or plants.
Oviraptorosaurs were similar in appearance, but had toothless horn-covered jaws. Their name means "egg thief reptile" because it appears they ate other dinosaurs' eggs.
LOCALITY: North America
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Ornithomimosauria
FAMILY: Ornithomimidae
GENERA: Dromiceiomimus
Elaphrosaurus
Gallimimus
Ornithomimus
Struthiomimus
9Pachycephalosaurs: The Boneheads
144 Million BC;15 Feet
MADAGASCAR
Like modern mountain goats, it seems pachycephalosaurs, or "thick headed reptiles," liked to bonk each other on the heads.
All the dinosaurs of this group had incredibly thick dome-shaped skulls, some with bony knobs and spikes on the sides of their heads and along their snouts. Some scientists believe that male pachycephalosaurs butted heads for the right to rule the herd.
These rare two-legged plant eaters had five-fingers and three toes and probably ate fruit, leaves, seeds and perhaps insects. They lived mostly in North America, but also in Europe, Central Asia, and even Madagascar.
LOCALITY: North America, Central Asia, Europe, Madagascar
ORDER: Ornithischia
SUBORDER: Pachyephalosauria
FAMILY: Pachycephalosauridae
GENERA: Pachycephalosaurus
Prenocephale
Stegoceras
Stygimoloch
CSauropods: Giant Dinosaurs
160 Million BC;90 Feet
NORTH AMERICA
The sauropods were giants among dinosaurs. They were large four-footed plant-eaters with long snake-like necks and tails. Some must have weighed more than several elephants.
Compared to the size of their bodies, sauropods had small heads, often about the size of a horse's head. Some of the more famous members of this group were Apatosaurus, Brachiosaurus and Diplodocus.
LOCALITY: Worldwide
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILIES: Cetiosauridae
Brachiosauridae
Camarasauridae
Diplodocidae
Titanosauridae
δStegosaurs: Roofed Reptiles
180 Million BC;21 Feet;2 Tons
SOUTHERN AFRICA
The stegosaurs, "roof reptiles," were the largest plated dinosaurs. They lived from the late Jurassic period to the end of the Cretaceous. Stegosaurs walked on all four feet, ate plants and had two rows of plates or spikes along their backs and necks. Some grew to as long as 30 feet.
But compared with their bodies, their heads were small, with little teeth and a toothless beak at the front of their mouths.
Fossils of stegosaurs have been found around the world, in North America, Europe, southern Africa, India and China.
LOCALITY: Africa, China, Europe, India, North America
ORDER: Ornithischia
SUBORDER: Stegosauria
FAMILY: Stegosauridae
GENERA: Kentrosaurus
Stegosaurus
Tuojiangosaurus
Wutermosaurus
[Troodontids: Bird-like Dinosaurs
73 Million BC;3 to 7 Feet
MONGOLIA
Troodontids, or Saurornithoidids, were a family of smart, somewhat birdlike, dinosaurs with the large brains and front-facing eyes of hunting animals.
They also had a sharp, killer claw on each back foot, like the famous claws of Deinonychus, though smaller.
Some scientists think these dinosaurs, which lived during the Late Cretaceous period, could have been as smart as some mammals.
LOCALITY: North America, Mongolia, southern Europe
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Deinonychosauria
FAMILY: Troodontidae
GENERA: Saurornithoides
Paronychodon
Troodon
ΦTyrannosaurids: Big meat-eaters
66 Million BC;39 Feet
NORTH AMERICA
The largest of the meat-eating dinosaurs were the tyrannosaurids, or "tyrant reptiles." Not only were they the largest meat-eaters, but they were also the largest of the two-legged, or theropod, dinosaurs.
These were sturdy animals with a short thick neck and slim tail. They had a vicious set of saw-edged teeth and in some cases a mouth large enough to swallow a human being. There being no humans around at the time, however, they probably ate the
duckbilled dinosaurs that roamed North America.
LOCALITY: North America, Asia
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Tyrannosauridae
GENERA: Albertosaurus
Alioramus
Daspletosaurus
Tarbosaurus
Tyrannosaurus
Nanotyrannus
yHow To Make A Fossil
66 Million BC
Everything we know about dinosaurs comes from studying the fossils they left behind. Not every animal or plant that died in the distant past created a fossil. Usually, whatever was left of a dead animal was eaten by scavengers or gradually dissolved into the earth by the forces of air and water. Occasionally, however, the conditions were just right to transform certain parts of an animal's body into a fossil that could be preserved for hundreds of millions of years.
The most frequent way for that to happen was if an animal's body ended up in a place where it would be quickly covered with layers of sediment or sand, therefore protecting it from decay.
The most likely place for this to happen was on the sandy bottom of the sea or a lake or river. Many times, dinosaurs that died by rivers or lakes were washed away by the water to a sandbar or sank to the water's bottom where their bodies were covered with soft sediment. It is also possible for dinosaurs to be fossilized in deserts where the fast-blowing sand could quickly cover up a body.
In either case, the soft parts of the dinosaur like the skin, muscles and organs eventually dissolved, leaving the harder parts like the skeleton and teeth preserved. Over the years, as more and more sediment covered the dinosaur's remains, minerals replaced the material of the bones or teeth and left a hardened duplicate of the original bone.
Usually, the hardest parts of an animal were the only parts fossilized, but sometimes the soft tissue such as the skin or muscle could be preserved in its original state, and at times, trace fossils, such as footprints in soft soil, were preserved.
½The Mystery of Life
1 Billion BC
EARTH
The first thing to remember about simple life forms is that there is nothing simple about them. The most basic cell has been compared to a factory carrying out as many functions as every type of factory on Earth put together.
Therefore, it is still something of a mystery how living things were first formed, but many scientists believe that in Earth's early ages rain carried chemicals from the air and ground into the oceans, making a salty soup out of which life evolved.
Though the molecules that make up living things are much more complicated than those found in the primitive oceans, experiments have shown that when acted upon by certain sources of energy, chemicals found on the young Earth could have produced the amino acids and nucleotide bases, which are to life as bricks, for example, are to buildings. Other theories suggest that these building blocks could have hooked together into more complicated proteins and nucleic acids to form "protocells," precursors to true living cells.
Some scientists theorize that after eons of reacting with each other and with other chemicals, protocells somehow developed skins that could absorb chemicals and grow larger without bursting. Gradually, over many generations, surviving protocells became more complex until some of them were able to grow and then split into two identical copies of the original cell, at which point they would be alive.
But other scientists, such as Nobel-Prize-winning biochemist Francis Crick, consider this chain of events so vastly improbable that they speculate early life forms may have drifted in from outer space.
Scientists are still searching for definite answers to the complex mystery of life.
Gallimimus: Chicken Mimic
86 Million BC;17 Feet;750 Pounds
MONGOLIA
Like its American cousins Struthiomimus and Ornithomimus, Gallimimus had a somewhat ostrich-like appearance, with long legs and a toothless skull.
It was larger than Struthiomimus and Ornithomimus, and could probably run at almost 35 miles an hour. It probably ate lizards and insects as well as plants.
Its hands were not built for grasping, so perhaps Gallimimus used them for digging.
LOCALITY: Asia
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Ornithomimosauria
FAMILY: Ornithomimidae
bTreasure of the Orient
1922 AD
GOBI DESERT, MONGOLIA
By the 1920s, scientists around the world were caught up in a frenzy to find clues to the origins of man. So in 1922, the American Museum of Natural History sent a huge expedition to Mongolia in the hopes of unearthing fossils of primitive man and prehistoric mammals. What they discovered instead was a vast and varied collection of dinosaur fossils, some of which had never been seen before.
The fossils were located in a sandy basin in the forbidding Gobi Desert where temperatures can range between 100 degrees in the summer and negative 100 degrees in the winter. Between 1922 and the present, numerous expeditions have been to the Gobi, uncovering entirely new species of dinosaurs, including Oviraptor, Stegoceras, Protoceratops and Velociraptor. In some of these cases, the fossils were found resting on the surface, covered only by a layer of fine dust.
One of the most fascinating fossil finds from the Gobi Desert excavations was a group of nearly perfectly preserved fossil eggs of Protoceratops, a small horned dinosaur related to Triceratops. The eggs were found arranged in a small depression in the ground that must have served as a nest. They were oval-shaped and not much larger than a human hand.
In the same area, scientists eventually discovered Protoceratops' fossils of all ages, from tiny hatchlings to full-sized adults.
sGryposaurus: The Hook-Nosed Dinosaur
81 Million BC;31 Feet;4.2 Tons
ALBERTA, CANADA
Gryposaurus, meaning "griffin lizard," was a large, hook-nosed plant-eating dinosaur with an arch of bone on its snout. It lived in the Late Cretaceous period and had the typical duck bill of hadrosaurids. Gryposaurus was named by dinosaurologist Lawrence Lambe.
LOCALITY: Canada
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hadrosauridae
½Apatosaurus: The Giant Dinosaur
149 Million BC;70 Feet;33 Tons
UTAH, UNITED STATES
One of the largest dinosaurs ever was Apatosaurus. A fully-grown Apatosaurus could measure up to 70 feet long.
As you can see from this movie, Apatosaurus' mouth was designed to eat plants. To grow to such a huge size it must have eaten tons of vegetation each day.
LOCALITY: Oklahoma, Utah, Wyoming, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Diplodocidae
└Hips Make the Dinosaur
225 Million BC
EARTH
One of the main ways of classifying dinosaurs is by their hip type, either saurischian (meaning "reptile-hipped") or ornithischian (meaning "bird-hipped"). All dinosaurs can be divided into one of these two groups.
Dinosaur hips were made up of three bones that could be found on each side of the pelvis: the ilium, the ischium, and the pubis. In reptile-hipped dinosaurs the ischium pointed backwards and the pubis pointed forwards. With these dinosaurs, the joints and connections between the hip and leg bones were very simple, which made it possible for the dinosaur to carry its legs directly beneath its body. In this fashion, the legs acted like the pillars of a building, capable of holding up a substantial amount of weight.
Among the reptile-hipped dinosaurs there were meat-eaters, such as Tyrannosaurus, and plant-eaters, such as Diplodocus.
Bird-hipped dinosaurs, on the other hand, were all plant eaters. Their hips were different from reptile-hipped dinosaurs because their pubis pointed backwards along with the ischium. Bird-hipped dinosaurs included some of the more distinctive-looking dinosaurs, such as the heavily armored Ankylosaurus, Stegosaurus and the crested Corythosaurus.
╝Homalocephale: The Flat Headed Dinosaur
79 Million BC;10 Feet;350 Pounds
CHINA
Although it was apparently a head-butting dinosaur, Homalocephale didn't have a dome on top of its head, as was typical of his cousins Prenocephale, Pachycephalosaurus, and Stegoceras.
Instead, Homalocephale -- its name means "even head" -- had a thick, flat, wedge-shaped head covered with knobs. Perhaps it used its head like mountain goats, butting rival males to establish who was in charge.
It walked on two legs spread widely apart. Perhaps this helped absorb the shock of smashing heads, or perhaps it indicates that Homalocephale gave birth to live young.
LOCALITY: North America and Central Asia
ORDER: Ornithischia
SUBORDER: Pachycephalosauria
FAMILY: Homalocephalidae
Nests in the Sand
1922-1925 AD
GOBI DESERT, MONGOLIA
Scientists first discovered dinosaur eggs during an expedition to Mongolia, where they found more than 50 fossil dinosaur eggs covered with sand in the Gobi Desert.
In this movie you can see a recreation of a hadrosaurus hatching.
≈Ichthyosaurus: Acrobat of the Seas
150 Million BC;6 Feet;230 Pounds
GERMANY
Ichthyosaurus looked like a fish, swam like a fish but, in fact, was a reptile, though not a dinosaur.
For nearly 80 million years, Ichthyosaurus cruised the open seas feeding off of schools of primitive fish which lived in the shallow waters surrounding the ancient continents. With its dorsal fin, streamlined body and strong, flexible tail, Ichthyosaurus resembled a modern dolphin. Like dolphins, Ichthyosaurus was probably quick and capable of impressive acrobatics both in and out of water. Also like a dolphin, Ichthyosaurus couldn't remain underwater forever and had to break the surface from time to time in order to breathe. To locate its prey, Ichthyosaurus had large eyes and heavy ear bones which transmitted the sounds of the sea. Over the years, scientists have found hundreds of well-preserved fossil Ichthyosauruses in rocks around Europe and North America.
Much of that land was once covered by water, so when an Ichthyosaurus died its body would descend to the sea floor where it would be covered with sediment and transformed into a fossil. One of the most amazing traits of Ichthyosaurus was that it gave birth to live young rather than lay eggs like other reptiles. Many fossils of Ichthyosaurus have been discovered with young Ichthyosauruses inside the skeleton of an adult. Some fossils even show the body of the baby Ichthyosaurus in the process of emerging from an adult body.
LOCALITY: Germany
CLASS: Reptilia
SUBCLASS: Diapsida
ORDER: Ichthyosauria
FAMILY: Ichthyosauridae
¿Iguanodon: Not an Iguana
125 Million BC;30 Feet;5 Tons
BERNISSART, BELGIUM
In 1809, part of an Iguanodon's giant shinbone was found in southern England. In 1819, some teeth and other bones were discovered and scientists at the time thought that they probably belonged to a gigantic mammal, like a rhinoceros. But then the geologist Gideon Mantell noticed that the teeth resembled those of a modern iguana, so he named the creature Iguanodon. Iguanodon was the second dinosaur to be discovered even though the word "dinosaur" had yet to be coined.
Iguanodon stood about 16 feet tall, measured 30 feet long and weighed close to five tons. It roamed the warm, humid Cretaceous landscape and fed on the rich abundance of plant life covering the land. Large numbers of Iguanodon skeletons have been found in England, Belgium and Germany, indicating to paleontologists that Iguanodon probably traveled in large herds.
Iguanodon had small "hooves" on its hands and feet, and its legs were long and sturdy. This giant dinosaur could have stood on its back legs to reach for higher bushes and plant life.
LOCALITY: Western Europe, Mongolia, North Africa, Western North America
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Igaunodontidae
ßJurassic: Dinosaurs Rule
208-146 Million BC
LAURASIA and GONDWANA
The supercontinent Pangaea began to break apart during the Jurassic Period. It split into Laurasia in the north (including what is now North America, Europe and Asia) and Gondwana in the south (South America, Africa, Antarctica, Australia and India), and creating the Atlantic Ocean in between.
During this time the great interior deserts became closer to the ocean, and therefore, moister. Plants, such as the short palm-like cycadeoids, tree-like cycads, ferns and tree ferns, began to flourish in a wide variety of places.
Shallow seas covered much of Europe and North America and became the playground not only for fish, but also for large marine reptiles, such as the plesiosaurs and ichthyosaurs. Above the sea and land, flying reptiles and birds swooped and dived.
New varieties of plant and meat eating dinosaurs appeared, and some grew huge. The famous sauropods, such as Diplodocus, roamed the earth, but there were also two-footed dinosaurs, both plant and meat-eaters.
Mammals at this time were mostly small burrowing or climbing animals who apparently tried to stay out of the way of the big meat-eaters.
But the last and longest period of the dinosaurs was yet to come. It was the Cretaceous Period.
NLambeosaurus: Crazy Crest
69 Million BC;30 Feet;2.4 Tons
BAJA CALIFORNIA, MEXICO
Lambeosaurus was a member of the hadrosaur family, the most common of dinosaur families. This duckbilled dinosaur had a tall, hollow, squarish crest on top of its head, and behind that a horn that pointed backward. It had hooflike feet and walked on all fours. One Lambeosaur found in Baja California, Mexico, appears to be about 54 feet long, making it largest hadrosaur known.
At one time scientists thought the strange headgear of Lambeosaur and its relatives was a snorkel and that the dinosaurs lived in the water. Now they believe these animals lived just on land.
The strange name means "Lambe's reptile," in honor of discoverer Lawrence Lambe, who found the first one in 1914.
LOCALITY: Baja California (Mexico), Montana, Saskatchewan
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Lambeosauridae
[Lesothosaurus: Feeling Sleepy?
210 Million BC;4 Feet;35 Pounds
LESOTHO, AFRICA
Little Lesothosaurus was built for the hot dry plains of southern Africa. Its skeleton was lightweight, with hollow limb bones, long back legs and a slender tail, short arms and a flexible neck.
Two Lesothosaurs skeletons were found curled up together as if they were estivating (like hibernating but during the summer so as to escape the heat) and around them were worn-down teeth, though each dinosaur had a full set of teeth. Maybe while they were
sleeping, they grew new teeth.
LOCALITY: Lesotho, Africa
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Fabrosauridae
Z Museums
1993 AD
LIBRARY
Welcome to the Dinosaur Adventure Library! You can use the card catalog in the library picture to find any topic you wish.
Just click on the card catalog drawer containing the topic you want to find, then click on the topic itself. Dinosaur Adventure will take you right to a screen on that topic.
To learn more about dinosaurs, check the lists of dinosaur museums below.
MUSEUMS
-- Academy of Natural Sciences; Philadelphia, Pennsylvania.
-- Academy of Sciences of Mongolia; Ulan-Bator, Mongolia.
-- American Museum of Natural History; New York, New York.
-- Argentine Museum of Natural Sciences; Buenos Aires, Argentina.
-- Australian Museum; Sydney, New South Wales, Australia.
-- British Museum (Natural History); London, England.
-- Carnegie Museum of Natural History; Pittsburgh, Pennsylvania.
-- Cleveland Museum of Natural History; Cleveland, Ohio.
-- Denver Museum of Natural History; Denver, Colorado.
-- Dinosaur National Monument; Vernal, Utah.
-- Field Museum of Natural History; Chicago, Illinois.
-- Geological Museum at the University of Wyoming; Laramie, Wyoming.
-- Institute and Museum of Geology and Palaeontology; Tubingen, Germany.
-- Institute of Palaeobiology, Warsaw, Poland.
-- Los Angeles County Museum of Natural History, Los Angeles, California.
-- Museum of Natural History; Princeton University, Princeton; New Jersey.
-- Museum of Paleontology; University of California, Berkeley; California.
-- Museum of the Rockies; Montana State University; Bozeman, Montana.
-- National Museum of Natural History; Paris, France.
-- National Museum of Natural History; Washington, D.C.
-- National Museum of Natural Sciences; Ottawa, Ontario, Canada.
-- Natural History Museum; Humboldt University; Berlin, Germany.
-- Natural History Museum of Los Angeles County; Los Angeles, California.
-- Peabody Museum of Natural History; Yale University, New Haven, Connecticut.
-- Provincial Museum of Alberta; Edmonton, Alberta, Canada.
-- Royal Ontario Museum; Toronto, Ontario, Canada.
-- Palaeontological Institute, Moscow, Russia.
-- Senkenberg Nature Museum; Frankfurt, Germany.
-- Tyrell Museum of Palaeontology; Drumheller, Alberta, Canada.
-- University Museum. Oxford, England.
-- Utah Museum of Natural History; University of Utah, Utah.
ÿLooking For Dinosaurs
1992 AD
Most of the dinosaur fossils that exist in the world today are buried beneath hundreds of feet of earth that has built up over millions and millions of years. That makes finding dinosaur fossils no easy task.
So how do the scientists who study dinosaurs, generally known as paleontologists, find their fossils? Very often purely by accident. The ground or rock around a fossil may have eroded enough to expose a part of the fossil. Sometimes, people like miners will stumble upon a collection of fossil remains while they are digging through layers of rock.
More often than not, paleontologists find dinosaur fossils by playing detective. The first place they look is where the rock is as old as a dinosaur would be. That means between 65 and 210 million years. Then, since most fossils were created when layers of sediment from a river or lake covered a dinosaur's body, they look in places where there is sedimentary rock.
Usually the sides of river canyons are the best places to start because the layers of rock are well exposed. Other good places can be where scientists suspect rivers or large bodies of water may have existed hundreds of millions of years ago.
¼Maiasaura: Good Mother Dinosaur
97 Million BC;30 Feet;3.2 Tons
MONTANA, UNITED STATES
The discovery of a large number of Maiasaura fossils has given scientists new insight into the social behavior of dinosaurs. It turns out the duck-billed Maiasaura liked to hang out together and take care of their young.
There are two major clues scientists have used to come to these conclusions. One is a vast boneyard that scientists have discovered in western Montana. The area is filled with as many as 10,000 skeletons of one particular kind of hadrosaur, the Maiasaura. Also, these skeletons range from about 10 feet long to 23 feet long, suggesting this herd was made up of different age Maiasaura. Apparently they had died from the smoke and fumes and ash of an exploding volcano.
This is significant because it shows Maiasaura was not a loner, but lived together in herds.
Another significant find in Montana was a nest of 15 baby Maiasaura. The babies were about three feet long, three times the size they were when they were born. (Scientists know newborn Maiasaura are about a foot long from other nests.)
Why weren't these big strapping young dinosaurs out on their own? Most reptiles are ready to face the world the moment they are born.
This is the question scientists had, and there are two possible answers, both which suggest these dinosaurs had a strong family relationship.
Either the parents brought food to the young dinosaurs or the young dinosaurs went out for food and then returned to the nest. Both these possibilities suggest a strong family relationship between parents and children.
No wonder the word "Maiasaura" means "good mother lizard."
LOCALITY: Montana, USA
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hadrosauridae
Megazostrodon: The First Mammal
180 Million BC;4 Inches;9 Ounces
LESOTHO, AFRICA
Contrary to popular belief, mammals appeared on the earth almost as long ago as dinosaurs. In fact, tiny shrew-like animals such as Megazostrodon were alive throughout the entire age of dinosaurs, scurrying among the legs of the giant Apatosaurus and ducking for cover when the voracious meat-eater Coelophysis came hunting for food.
These early mammals were small and furry and looked a lot like modern mice. They were also warm-blooded and suckled their young babies. Despite these many mammal-like characteristics, it is thought they still laid leathery eggs.
Mammals like Megazostrodon may have evolved from a special group of reptiles during the Late Triassic or Early Jurassic Period, some 208 million years ago. During that time, these animals developed traits that made them well-suited for a highly active lifestyle. As opposed to having only one kind of teeth, as most reptiles did, early mammals developed four types. Their skeletons changed so that their limbs were more flexible and able to move more quickly. Also, mammals developed a shorter rib cage and larger lungs which could inhale and exhale more rapidly. Most importantly, though, mammals like Megazostrodon became warm-blooded, which meant they relied on the food they ate for sustaining their body temperature rather than the outside environment. That enabled mammals to maintain a higher level of activity throughout the day than cold-blooded reptiles could.
Megazostrodon's diet probably consisted of small insects and reptiles, and scientists believe that Megazostrodon did most of its hunting and scavenging during the night to avoid being eaten by hungry meat-eating dinosaurs!
LOCALITY: Lesotho, Africa
CLASS: Mammalia
SUBCLASS: Prototheria
ORDER: Triconodonta
FAMILY: Morganucodontidae
The President Protects Fossils
1909 AD
VERNAL, UTAH
When a young scientist named Earl Douglass spotted a massive Diplodocus thigh bone resting on a sandstone ledge near Vernal, Utah, he had no idea he was on the verge of one of the richest fossil finds in history. Douglass, who worked for the Carnegie Museum in Pittsburgh, returned to the site a year later hoping to uncover the rest of what turned out to be a 70-foot long Diplodocus skeleton. As Douglass and others began to excavate, they soon discovered thousands of dinosaur bones lodged in the stone around the skeleton.
For the next 13 years, the Carnegie Museum sent one excavation team after another to the stone quarry, unearthing the first complete skeletons of giant plant-eaters such as Apatosaurus, Diplodocus and Camarasaurus. They also found the bones of Stegosaurus and the meat-eating Allosaurus that must have preyed on the slower-moving plant-eaters millions of years ago.
Later, however, when amateur fossil hunters began combing the land around the quarry in search of more bones, President Woodrow Wilson turned the site into a national park to protect the fossils from any damage. Today, visitors can go to Dinosaur National Monument, as it is now called, and see a long wall of stone filled with dinosaur bones still in their original resting place.
IMosasaurus: What's that in the Mine?
75 Million BC;45 Feet;1.5 Tons
MAASTRICHT, NETHERLANDS
The first Mosasaurus was found in a mine in Maastricht, Netherlands. At first, nobody was sure what it was. It looked like a whale to some, or like some kind of a breathing fish to others.
Eventually the fossil made its way to Paris, France, where anatomist Georges Cuvier identified it as a giant marine reptile.
Mosasaurus, meaning "Muese reptile" after the Muese River which flows by Maastricht, was a common creature of the Late Cretaceous Period. Commonly Mosasaurs measured up to about 30 feet, though there may have been some as long as 45 feet.
Their teeth were constantly replaced as they lost them and they had a jointed lower jaw that enabled them to open their mouth very wide to eat large fish. We know it ate fish because petrified fish skeletons have been found in Mosasaur stomachs.
Though the first mosasaur was found in the Netherlands, most of the best fossils come from chalk beds in western Kansas.
LOCALITY: Europe, North America
CLASS: Reptilia
SUPERORDER: Lepidosauria
ORDER: Squamata
SUBORDER: Lacertilia
FAMILY: Mosasauridae
Nanotyrannus: A Young Tyrannosaurus
80 Million BC;16 Feet;1.2 Tons
MONTANA, UNITED STATES
At about 16 feet long, Nanotyrannus was a relatively small meat-eating dinosaur. Its name means "tiny tyrant" and it is known only by a skull found in Montana and a few teeth from South Dakota.
For a while scientists thought it might be an Albertosaurus, except that its eyes faced forward, while Albertosaurus' eyes faced outward. These forward-facing eyes meant it must have been good at judging distances, so it may have been a good hunter.
While it appears not to have been an Albertosaurus, some scientists think it may have been a young tyrannosaurus because some of the bones were not fused together, as would be the case if it was fully grown.
LOCALITY: Montana, USA
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Tyrannosauridae
Building a Nest
85 Million BC
MONTANA, UNITED STATES
Once scientists thought dinosaurs left their eggs to bake in the sun, but as you can see in this movie, they now hold a different view.
Now they have found evidence that dinosaurs built nests and even cared for their young after they were born.
UOrnithomimus: The Ostrich Dinosaur
74 Million BC;13 Feet;430 Pounds
ALBERTA, CANADA
This dinosaur looks something like an ostrich. It has long, powerful legs that look like they were built for running, no teeth and may even have had a beak.
Of course, Ornithomimus (which means "bird mimic") isn't really related to the ostrich. Unlike the ostrich, it had a long tail that made up about half of its 13-foot length, and instead of wings, it had arms and hands.
Scientists think Ornithomimus may have eaten small plants and animals.
LOCALITY: Alberta, Canada
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Ornithomimosauria
FAMILY: Ornithomimidae
ΣOrodromeus: Fast Runner
96 Million BC; 6 Feet;155 Pounds
MONTANA, UNITED STATES
Orodromeus, meaning "mountain runner," was a swift-footed dinosaur about 6.5 feet long. It had long running-type legs, short arms and simple teeth that it may have used to eat fruits and perhaps insects.
Mother Orodromeus laid about a dozen eggs at a time in a spiral. When the little dinosaurs were ready to hatch, they pecked their way out of the shell.
LOCALITY: Montana, USA
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hypsilophodontidae
òOviraptor: Eggs Over Easy
83 Million BC;6 Feet;225 Pounds
GOBI DESERT, MONGOLIA
The first complete fossil of Oviraptor was discovered in Mongolia just a few feet from a nest of fossilized Protoceratops eggs. It is very likely that the Oviraptor was about to make a meal of the eggs when an angry adult Protoceratops caught it in the act and killed it. For that reason Oviraptor got its name, which means "egg thief."
Oviraptor was an unusual dinosaur. Measuring five to six feet long, it had a short head and a massive pair of toothless jaws shaped like a beak. With strong muscles in its mouth, Oviraptor must have had a powerful bite that was useful for breaking through hard surfaces, such as the eggs of other dinosaurs. Another interesting feature was a unique crest above Oviraptor's snout that was full of air passages and openings for its nose.
LOCALITY: Mongolia
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Oviraptorosauria
FAMILY: Oviraptoridae
ïOwen: This Is No Lizard!
1841 AD
ENGLAND
By 1841, several major dinosaur fossil discoveries had been made around England. Yet, most of the scientists who studied them believed they were nothing more than members of a group of giant lizards. That is, until Sir Richard Owen took a closer look at the evidence.
Owen was a famous British anatomist who studied the physical relationships between different groups of animals. When Owen studied the three most important fossil discoveries at the time, he quickly concluded that the bones were not at all like the bones of any lizard alive at the time. In fact, they were so different that he believed the fossils must have come from an entirely different group of animal which had long since vanished from the earth. He called this new group of animal "Dinosauria" which meant "terrible reptile" or "fearfully great reptile."
Owen described these creatures as being giant elephant-like reptiles which lumbered clumsily on all fours. Eventually, Owen published his findings in a book which created an enormous stir in England where people were fascinated to discover that a race of huge animals inhabited the earth long before there were people.
`Pachycephalosaurus: Biggest Bonehead
71 Million BC;15 Feet;900 Pounds
WYOMING, UNITED STATES
Pachycephalosaurus lived in the Late Cretaceous period and was the largest and last of the boneheaded dinosaurs.
Its head measured two feet long and had a tall dome on the top of its head that measured up to 10 inches thick. Also, along the edges of its skull and on its snout were bumps of bone.
Pachycephalosaurus, meaning "thick-headed lizard," probably crashed head to head against others of its own kind in contests to establish social standing.
LOCALITY: Wyoming, USA; Alberta, CANADA
ORDER: Ornithischia
SUBORDER: Pachycephalosauria
FAMILY: Pachycephalosauridae
BParasaurolophus: The Trumpeter
84 Million BC;33 Feet;4 Tons
ALBERTA, CANADA
Of all the dinosaurs in history, Parasaurolophus must have had one of the most distinctive-looking heads. The crest of this 33-foot long duck-billed dinosaur measured almost six feet in length and was made of a strong but hollow tube filled with nasal passages. These nasal passages connected from the creature's nostrils back to the very tip of the crest.
When scientists first discovered Parasaurolophus, it was thought that the crest was used as a kind of snorkel, but that could not have been farther from the truth since the tip of the crest didn't have an opening in it! There are plenty of other theories for how Parasaurolophus might have used this oddly shaped crest. It could have been used like a trumpet, making sounds to warn others of danger or to attract mates. These dinosaurs, which traveled in herds through the jungles of North America, had very good eyesight and may have used their unique headgear as a form of identification.
LOCALITY: New Mexico, Utah, USA; Alberta, Canada
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Lambeosauridae
▐Patagosaurus: South American Sauropod
162 Million BC;50 Feet;18 Tons
ARGENTINA
Patagosaurus was a medium-sized sauropod about 50 feet long and one of only two known sauropod dinosaurs to be found in South America. This creature takes its name from the Patagonia region of Argentina, where it was found.
Patagosaurus, minus its skull, was found in rocks about 15 million years older than those in which North American sauropods have been found.
LOCALITY: Argentina
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Cetiosauridae
VDiplodocus: Teeth Like Rakes
153 Million BC
WYOMING, UNITED STATES
Imagine eating with just your front teeth. That's what Diplodocus did.
The giant Diplodocus, which grew up to 100 feet long, had a set of weak, pencil-like teeth in the front of its jaws only.
You can see them here. Notice how dull they are compared to the powerful, sharp teeth of the meat-eating dinosaurs.
Because it didn't have back teeth, scientists believe Diplodocus must have used its teeth mostly to rake leaves off of trees and then swallowed its food unchewed.
Perhaps stones that Diplodocus had swallowed earlier would have helped it digest its food.
╞Quetzalcoatlus: The Robot Flies
Jan. 7, 1986;18 Feet;15 Pounds
EL MIRAGE DRY LAKE, CALIFORNIA
On a windy day one hundred million years after becoming extinct, the largest know pterosaur flew again.
Using the latest aircraft technology, Paul MacCready, known for his human-powered flying machines, created a mechanical Quetzalcoatlus. Instead of flesh and bones, this pterosaur was filled with electromechanical and electronic devices to control its flight. The new Quetzalcoatlus was patterned after fossilized bones of the earlier version.
Though controlled from the ground, much in the manner of a model airplane, the robot also had sophisticated internal electronics to steady it while in flight.
Scientists believe the original Quetzalcoatlus was probably a gliding creature that had excellent vision, preying on smaller animals or eating the carcasses of decaying dinosaurs.
LOCALITY: California, USA
SUPERORDER: Archosauria
ORDER: Pterosauria
SUBORDER: Pterodactyloidea
FAMILY: Ornithocheiridae
¥Plateosaurus: First Large Dinosaur
225 Million BC;23 Feet;2.2 Tons
TROSSINGEN, GERMANY
Plateosaurus, or "flat reptile," was one of the first large plant-eating dinosaurs known as "prosauropods." These were the ancestors of the much larger "sauropods," which includes Brachiosaurus and Apatosaurus.
Plateosaurus lived during the Late Triassic and Early Jurassic Periods and ranged all over what is now northern Europe. At a major fossil site in Germany dozens of Plateosaurus skeletons have been uncovered at the same location, leading some scientists to believe that this dinosaur traveled in large herds as it browsed among trees and bushes, which were its food.
Plateosaurus measured up to 23 feet long, with a tail that made up almost half its length. Plateosaurus had a rather small head compared to the rest of its body. Its many leaf-shaped teeth had large, coarse serrations very similar to modern plant-eating lizards.
Plateosaurus probably spent most of its time walking around on all fours, though occasionally it reared up on its strong back legs to nibble at the tops of trees.
LOCALITY: England; France; Germany; Switzerland
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Prosauropoda
FAMILY: Plateosauridae
╕Plesiosaurus: Reptile of the Sea
205 Million BC;7 Feet;195 Pounds
GERMANY
Plesiosaurus was the earliest member of the ocean-going group of reptiles called Plesiosaurs. These seven-foot-long marine reptiles cruised the shallow seas around England and Germany in search of their prey: smaller fish. Instead of limbs like other reptiles, Plesiosaurus developed long, narrow penguin-like flippers and short tails.
Plesiosaurus, or "ribbon reptile," used its paddle-shaped flippers much like a sea turtle does. Instead of rowing backwards and forwards, Plesiosaurus flapped its paddles up and down so that it probably looked like it was "flying" through the water when it swam. Plesiosaurus also laid its eggs just like a sea turtle does, in nests that were dug out in the sand. Because of their long necks and lack of any protective "armor," they would have been easy prey for enemies as they waddled up the beach to lay their eggs.
Plesiosaurus was an expert fish-catcher. Held high above the water with its long neck, Plesiosaurus' head could spot fish beneath it, and then snap them up with its razor sharp teeth.
LOCALITY: England; Germany
LENGTH: 7 feet
WEIGHT: Unknown
CLASS: Reptilia
SUBCLASS: Diapsida
SUPERORDER: Sauropterygia
ORDER: Plesiosauria
EHow the Solar System Started
4.6 Billion BC
SOLAR SYSTEM
Though the details are not fully understood, it appears our solar system started about 4.6 billion years ago as a whirling disc of hot hydrogen gas mixed with heavier atoms from ancient supernova explosions.
Gravity pulled the hydrogen together, toward the center of the disc. The hydrogen became more and more compressed until a nuclear fusion reaction began, generating energy. The Sun was born.
The remaining tenth of a percent of solar material condensed into smaller bodies that eventually became the planets. Leftovers became moons, comets and asteroids.
Earth Comes Alive
1 Billion BC
EARTH
Close to 2.5 billion years ago, the earth's surface and atmosphere were stable enough to support the first forms of primitive life. In the giant seas that covered the planet, single-cell organisms began to make their appearance. Most of them were very simple single-cell bacteria that fed on chemicals in the ocean's waters.
Over time, a simple organism known as blue-green algae appeared and spread across the seas. Blue-green algae, still alive today, were important to the future of the planet because they used sunlight and water to make food, and, in the process, created oxygen. As the blue-green algae thrived in the earth's seas, they began to fill the atmosphere with oxygen. Soon, the algae became so numerous that they formed huge reefs called stromatolites.
Earth: The Once-Poisonous Planet
4 Billion BC
EARTH
For nearly 1.5 billion years after the formation of the earth, the planet was a seething, poisonous place filled with volcanoes and covered by dark clouds of water vapor and poisonous gas. There was no life anywhere on the planet. And the air, water and land as we know them today did not exist.
It took hundreds of millions of years just for the earth's molten surface to finally cool and harden. As it did, poisonous gases and water vapor were expelled from the earth's core, creating the first primitive atmosphere. No living thing could have breathed in that atmosphere since there was no oxygen and most of the gases in it were deadly. All around the planet there were erupting volcanoes and lakes of lava.
Over time, the earth's surface cooled enough so the water vapor in the atmosphere began to condense and turn into rain. Then for millions of years, it rained nearly continuously, filling up the depressions in the earth's surfaces with what are now our seas and oceans.
Eventually, the rain stopped and the clouds covering the earth thinned. For the first time in many millions of years, the sun shone through to the earth's surface. At around the same time, much of the poisonous gas in the atmosphere escaped into space, setting the stage for the development of the first life forms.
£Protoceratops: Frilly Dinosaur
82 Million BC;6 Feet;400 Pounds
MONGOLIA, ASIA
Fighting the brutally hot winds of Mongolia's deserts, an American Museum of Natural History expedition in the early 1920s made a startling find. They unearthed masses of complete skulls and skeletons of Protoceratops, the first of the horned dinosaurs, known as protoceratopids. Living 90 million years ago, Protoceratops was the distant ancestor of the larger and more familiar Triceratops. They shared many of the same features. Measuring six feet long and weighing close to 400 pounds, Protoceratops had a large, heavy skull framed by a bony neck frill which was made lighter by two window-like openings in the skull. It also had a narrow, parrot-like beak with powerful, toothed jaws.
Protoceratops had no horns, although it had a crest, or nose-horn, along the top ridge of its snout. Some experts believe that this bump, only associated with the male of the species, was used in combat between enemies.
By far the most famous discovery made during this trip was a whole nest of very well-preserved Protoceratops eggs along with skeletons of hatchlings and juveniles. The eggs had been carefully laid out in a circular fashion in shallow depressions made in the sand of an earlier desert at this same site, but the swirling sands had probably covered the nest so deeply that the babies never had a chance to hatch.
LOCALITY: Mongolia
ORDER: Ornithischia
SUBORDER: Ceratopsia
FAMILY: Protoceratopsidae
ÖPteranodon: The Flying Reptile
75 Million BC;23 Feet;37 Pounds
GERMANY
Pteranodon belongs to an ancient group of flying reptiles called "pterosaurs" that lived at the same time as the dinosaurs. When the first pterosaur fossils were discovered in Germany in 1784, scientists thought they were aquatic animals. It took them 100 years to finally recognize they were flying reptiles!
Pteranodon had one of the largest wingspans of all the pterosaurs, measuring as much as 23 feet wide. This 37-pound creature had a sharp beak with no teeth, and almost half the length of its head was taken up by a bony, protruding crest whose purpose is still not fully understood. Some scientists think it may have been decorative and useful for attracting mates, while others believe that it may have acted like a rudder to steady Pteranodon during flight.
Pteranodon probably flew over the seas of what are now Kansas and Texas at speeds of up to 23 miles per hour, feeding on fish and mollusks. Because it had no teeth it probably caught fish like modern pelicans do, swallowing them whole.
LOCALITY: England; Germany; Midwestern North America
SUPERORDER: Archosauria
ORDER: Pterosauria
SUBORDER: Pterodactyloidea
FAMILY: Ornithocheiridae
░Quetzalcoatlus
68 Million BC;50 Feet;190 Pounds
TEXAS, UNITED STATES
Until recently, the giant-winged Pteranodon was thought to have been the largest of the flying reptiles known as "pterosaurs." But in 1972 the remains of an even more enormous pterosaur was discovered in Big Bend National Park in Texas.
Quetzalcoatlus, or "feathered serpent" -- named after an Aztec god -- would have been the largest and heaviest flying reptile by far. The fossilized remains indicate that this giant pterosaur would have weighed nearly 190 pounds and had a wingspan of close to 50 feet, almost the same size as a small airplane!
Quetzalcoatlus probably lived far inland, away from water. Like other pterosaurs, Quetzalcoatlus' wings were made of skin stretched along the lengths of greatly elongated fourth fingers of each claw. Its neck was probably longer than the earlier Rhamphorhynchus, and its head was probably more elongated. Scientists think Quetzalcoatlus had excellent vision and behaved like a modern vulture, spotting its prey from afar, then attacking or feeding on the carcasses of decaying dinosaurs.
LOCALITY: Texas, USA
SUPERORDER: Archosauria
ORDER: Pterosauria
SUBORDER: Pterodactyloidea
FAMILY: Ornithocheiridae
Rhabdodon: Transylvanian Herbivore
66 Million BC;13 Feet;320 Pounds
TRANSYLVANIA, ROMANIA
Rhabdodon priscus was a bird-hipped, plant-eating dinosaur that grew to about 13 feet long. It may have been a member of either the hypsilophodont or iguanodontid families. It lived in Transylvania, part of Romania, during the Late Cretaceous Period. Rhabdodon was an ornithopod, a group of small bipedal herbivores which include Lesothosaurus, Hypsilophodon and Dryosaurus.
LOCALITY: Romania, France, Austria
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hypsilophodontidae
îRhamphorhynchus: Sea Skimmer
145 Million BC;3 Feet;17 Pounds
SOUTHERN GERMANY
With its long beak and outwardly pointing teeth, Rhamphorhynchus skimmed across the Late Jurassic seas snatching up fish for its nourishment. Small and agile, Rhamphorynchus was a member of a group of flying reptiles known as pterosaurs.
Like other pterosaurs, Rhamphorhynchus flew through the air on wings made of thin skin that was stretched along their bodies to the very tips of their extremely long fourth fingers, or "wing fingers." Well-preserved fossils of Rhamphorhynchus have been found in the limestone quarries of southern Germany which show the membranous skin of their wings and long kite-like tails, which helped guide these creatures in flight.
It had a wingspan of about three feet three inches, and thin fibers running from the front to the back of the wings strengthened them greatly, much like the wing structure of the modern bat. Rhamphorhynchus' tail was also very long and strengthened by many thin, bony rods that ended in a small, flared-out flap of skin resembling a kite.
LOCALITY: Germany; Tanzania, Africa
SUPERORDER: Archosauria
ORDER: Pterosauria
SUBORDER: Rhamphorychoidea
FAMILY: Rhamphorynchidae
∩Scutellosaurus: Early Bird Hips
208 Million BC;4 Feet;55 Pounds
ARIZONA, UNITED STATES
One of earliest ornithischian, or bird-hipped, dinosaurs was the armored Scutellosaurus. It was an unusual creature because most armored dinosaurs had four legs, but Scutellosaurus walked on two legs.
Scutellosaurus was about four feet long. It had a slim head and strong jaws for eating plants. Its very long tail may have been a good whip to use against predators.
Scutellosaurus means "shield reptile," and takes its name from the several hundred little bony plates that cover its neck, back, ribs and tail. Some scientists think Scutellosaurus may be the ancestor of other armored dinos, like Stegosaurus and Ankylosaurus.
LOCALITY: Arizona
ORDER: Ornithischia
SUBORDER: Scelidosauria
FAMILY: Scutellosauridae
àSeismosaurus: Biggest of the Big
144 Million BC;140 Feet;150 Tons
NEW MEXICO, UNITED STATES
From preliminary investigations, Seismosaurus, or "earth shaker reptile," is the largest dinosaur ever found. Bigger even than Supersaurus and Ultrasaurus, both found in Colorado.
Seismosaurus, located in central New Mexico but not yet fully excavated, may be as long as 140 feet. It is related to Diplodocus, with long front legs, shorter back legs, a long neck and tail.
To get a feel for its possible size, think about this: a single vertebrae scientists found measured five feet long.
LOCALITY: New Mexico, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Diplodocidae
Dinosaurs' Bumpy Skin
200 Million BC
Dinosaurs were covered with scales; not like the scales of a fish or the feathers of a bird, which overlap, but more like the skin of a crocodile.
Dinosaur scales were thick, round or multi-sided bumps arranged edge to edge in a pebbled pattern. The scales were bigger where the skin did not have to bend and smaller where it needed to be flexible. Some dinosaurs, such as the ankylosaurs, had bony plates attached to their skin for additional protection.
Some scientists think a few types of dinosaurs had feathers. The reason they believe this is that if dinosaurs evolved into birds, they must have had feathers before they began flying. Nobody has found feathers on dinosaur fossils, but Russian scientist Seriozha Kurzanov found a dinosaur with a ridge along the back edge of its forearm that he thought might have been where feathers were attached.
While we know a little about dinosaur skin, we know nothing about its color. All scientists can do is guess from the colors of today's animals. Perhaps some dinosaurs were colored to blend in with their background. Maybe the biggest plant-eaters were just one plain color, like the elephant, since they didn't need protection. Perhaps some were bright colors to attract a mate. We don't know, but it is fun to guess.
âWere Dinosaurs Social Animals?
73 Million BC
Once scientists thought dinosaurs were very dumb and slow, dragging their tails on the ground. They thought they laid their eggs and left them to bake in the sun. But this primitive view of dinosaurs has given way to a more complex understanding of these amazing creatures.
Now scientists believe some dinosaurs had social structures, that some mother dinosaurs cared for their young, and that they were even smarter than previously thought.
Scientists have found that Maiasaurs arranged their nests near each other and took care of their babies instead of abandoning them. Nests have been found with so many Protoceratops eggs that it appears it was a community nest. Dinosaurs have been found in mass graves, covered by volcanic ash or river mud. This suggests they traveled together in herds.
The duckbilled Lambeosaurs had head crests that could have been used to toot a warning to other Lambeosaurs, or attract a mate, or call the children home to their nest.
Though most meat-eaters tended to hunt alone, as do many meat-eaters today, apparently some of them, such as the fierce Deinonychus, may have hunted in packs, like dogs or wolves.
╬Death Ray for Dinosaurs?
65 Million BC
One long-standing explanation for why dinosaurs died so mysteriously is that a star in a nearby constellation exploded and bathed the earth in deadly cosmic rays. If the star's explosion was close enough, then many animals, both large and small, would have been killed.
But there is one major problem with this theory. Why is it that some animals (such as birds, mammals, and crocodiles) survived while others (like dinosaurs, and marine reptiles) did not?
╠Stegosaurus: The Plate-Backed Dinosaur
163 Million BC;21 Feet;2 Tons
COLORADO, UNITED STATES
Though not always able to outrun its carnivorous foes, the 21-foot-long, two-ton Stegosaurus always had a final line of defense, its bony plated back and spiny tail.
If cornered or outmaneuvered by a larger enemy, the Stegosaurus' back plates afforded some protection while the four to eight spikes on the end of its tail (which grew as long as four feet) made it dangerous for any foe to approach too carelessly.
Paleontologists still don't agree about the placement of the vertical plates along the Stegosaurus' back, which you can see in this movie. The plates are not attached to bone, but were embedded in the dinosaur's back, which makes it difficult to tell if they were in a single row, double row or a combination of the two.
Many scientists believe the vertical plates may also have served as warming or cooling fins, picking up heat from the sun when the weather was cool to warm the Stegosaurus, or giving off heat when it was too hot.
Stegosaurus bones have been found in Colorado and Wyoming. They are believed to have lived primarily in the western part of North America.
LOCALITY: Colorado, Wyoming, USA
ORDER: Ornithischia
SUBORDER: Stegosauria
FAMILY: Stegosauridae
╤Stegosaurus: The Plant Eater
157 Million BC;21 Feet;2 Tons
COLORADO, UNITED STATES
Look how big you can grow if you eat your vegetables!
Stegosaurus had a small mouth with small teeth and apparently ate only small plants, but this peaceful dinosaur grew to 21 feet long and weighed up to two tons.
In addition to having small teeth, Stegosaurus also had a small brain. It may even have had the smallest brain in comparison to its body size of any dinosaur. Stegosaurus' brain was only about the size of a walnut.
The word "Stegosaurus" means "roofed reptile." It was named this because scientists originally thought the plates on its back lay flat to form a protective roof.
LOCALITY: Colorado, USA
ORDER: Ornithischia
SUBORDER: Stegosauria
FAMILY: Stegosauridae
┼Stegoceras: The Crash Helmet Dinosaur
78 Million BC;6 Feet;120 Pounds
ALBERTA, CANADA
Stegoceras was certainly not a dinosaur with which to butt heads. This dinosaur was built almost entirely for ramming its uniquely shaped head into other dinosaurs.
Stegoceras belonged to a family of dinosaurs known as "thick-headed reptiles," or pachycephalosaurs, because of their dome-shaped bony heads. Discovered in North America in the early part of this century, these plant-eating dinosaurs had high foreheads and massively dense skulls that were made up entirely of thickened bone. Scientists believe that Stegoceras used its giant "crash helmet" to butt the heads of other males of its group, a lot like the behavior of modern mountain goats.
Living in the Late Cretaceous Period, Stegoceras roamed the plains of North America, traveling in herds. Adults grew to about six feet in length and weighed close to 120 pounds.
LOCALITY: Alberta, Canada
ORDER: Ornithischia
SUBORDER: Pachycephalosauria
FAMILY: Pachycephalosauridae
╖Struthiomimus: Ostrich-Sloth
77 Million BC;13 Feet;440 Pounds
ALBERTA, CANADA
Struthiomimus means "ostrich mimic," and it is interesting just how similar to an ostrich it appears to be.
Just like an ostrich, Struthiomimus stood on two legs, had a long flexible neck, a small head, and judging from the appearance of its skull, it also had a beak.
However, it had a few notable differences. It had a long tail for balance and arms instead of an ostrich's stubby wings, and its arms were shaped like those of a sloth, which hangs upside down in trees all day.
The shape of the arms has led some scientists to think that Struthiomimus ate mostly plants, and used its long arms to pull the branches of trees down to its mouth.
Others think Struthiomimus may have eaten insects as well, or possibly that it lived along the ocean shore, eating shrimp and crabs.
LOCALITY: Alberta, Canada; New Jersey, USA
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Ornithomimusauria
FAMILY: Ornithomimidae
#Stygimoloch: To Butt or Not to Butt
83 Million BC;7 Feet;175 Pounds
MONTANA, UNITED STATES
Stygimoloch, or "demon from the river Styx," was one of the head-butting variety of dinosaurs called pachycephalosaurs, but some scientists think it may not actually have used its head to butt with.
Unlike other pachycephalosaurs, its domed skull was covered with long spikes and horns that looked dangerous, so it may have been enough for Stygimoloch to display its headgear to establish its social standing.
LOCALITY: Montana, USA
ORDER: Ornithischia
SUBORDER: Pachycephalosauria
FAMILY: Pachycephalosauridae
rStyracosaurus: Spiked Reptile
80 Million BC;18 Feet;3 Tons
MONTANA, UNITED STATES
If you were a meat-eating dinosaur and had to stare a herd of Styracosaurus in the face, you might look elsewhere for your supper.
Like other plant-eating ceratopians, the 18-foot-long Styracosaurus had a massive, armor-plated head with heavy-duty spikes that would make any predator beware. While the better-known and larger Triceratops had a nose horn and two large eyebrow horns, Styracosaurus had a large nose horn and large sharp spikes around the upper edge of the armored frill that covered its neck.
Ceratopian fossils have been found in large bone beds in Montana and Alberta, in North America. In these beds all the skeletons are of the same variety and at different ages of life. This suggests they were members of a herd and were drowned during a flood.
If they were herd animals, perhaps they formed circles with their heads facing outward to ward off predators. Can you imagine a hungry meat-eater circling a herd, only to see sharp spikes and armor plate facing him at every point?
LOCALITY: Alberta, Canada; Montana, USA
ORDER: Ornithischia
SUBORDER: Ceratopsia
FAMILY: Ceratopsidae
ÅDinosaurs Roam the Earth
250 Million BC
PANGAEA
Looking down on earth from space 200 million years ago, you would have seen a very different world.
Instead of the familiar continents, you would have seen one super-continent called Pangaea, and one gigantic ocean, and on the earth would be large ferns and conifer trees, many that would be strange to us today.
Most impressive, though, would be the dinosaurs. While some of these reptiles (whose name means "terrible lizard") were as small as a chicken, others were taller than a three-story building.
These great creatures appeared on earth about 225 million years ago and ruled until about 65 million years ago.
The first part of their reign was during the Triassic Period. During that time all the earth's land was in one continent, so the dinosaurs could spread freely across the earth. Also, the weather was warm and swamps covered much of the land.
During the next period, the Jurassic, the weather remained warm and plants and animals increased rapidly, but the continents had begun to drift apart.
The Cretaceous Period marked the end of the dinosaurs. The continents drifted further apart and the earth's climate became more varied.
Removing Fossils: Easy Does It
Finding a fossil is one thing. Removing it from the ground without damaging it is quite another. When most dinosaur fossil sites are discovered, only a fragment of the fossil is visible. The rest is usually embedded in hard earth or rock. Using very special tools and techniques, experienced fossil collectors can take weeks just to excavate the fossils out of a small patch of ground.
First, the area where the fossil has been discovered must be labeled, photographed and drawn so that records will be available for researchers to use in the future. Most of the time, the fossil bones are cracked or crumbly and need to be painted with shellac or glue to harden the fossil surface. Then they are usually covered with moistened paper until the fossils look like they are made of papier mache'. The next step is to cover the wet newspaper with burlap soaked in plaster. In most cases, paleontologists dig a trench around the fossil and wrap the jacket of newspaper and burlap almost completely around the fossil. At this stage, the paleontologists can break the fossil free from the site with little or no harm done to it. If a fossil is small enough, excavators can scrape away the earth around the fragment and then carry it away.
Much larger fossils, such as the skull of a Triceratops or the thigh bone of an Apatosaurus, can require that huge pieces of rock surrounding the fossil be removed using power hammers and sometimes even explosives. When a large enough block has been carved out, the fossil can be carried away by tractor or truck.
Tanzania: Finding the Big One
1909 AD
TENDAGURU HILL, TANZANIA
Buried deep beneath the ancient rock of southern Africa are the fossils of numerous varieties of dinosaur.
Between 1909 and 1912 two German paleontologists, Werner Janensch and Edwin Hennig, hired hundreds of untrained African natives to dig though the bone pits of what is now Tanzania. For three years, the workers labored in the sweltering heat, unearthing thousands of bones that they then crated and carried by foot to a distant port town on the east coast of Africa.
Among these bones, some of which weighed hundreds of pounds or more, the fossil hunters discovered the nearly complete skeleton of the giant dinosaur Brachiosaurus. When it was reconstructed at the East Berlin Natural History Museum in Germany, the skeleton stood 40 feet tall, as high as a three-story building, and the tallest complete dinosaur skeleton in the world.
Many other types of dinosaurs were found at the same site, including relatives of the spiny-plated Stegosaurus and giant plant eaters of North America.
Tarbosaurus: Little Tyrannosaurus
82 Million BC;40 Feet;7 Tons
MONGOLIA
Thirteen Tarbosaurus skeletons have been found in Mongolia. This "alarming reptile," as its name means, was first discovered in 1955 in the Nemegt Basin in that country. The bones are so much like those of Tyrannosaurus that many experts think it was essentially the same animal. However, the Tarbosaurus skeletons are somewhat smaller than those of Tyrannosaurus, and there are some small differences in the skull.
LOCALITY: Mongolia
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Tyrannosauridae
∙Gideon Mantell Finds Fossil Teeth
1822 AD
LEWES, ENGLAND
For thousands of years, dinosaur fossils turned up without anyone knowing exactly what they were. In the middle ages, some people even thought that dinosaur fossils were actually the bones of ancient dragons or giants. That all changed in 1822, when a quiet English doctor named Gideon Mantell became the first person to prove that a dinosaur fossil was actually from a race of prehistoric animals.
It began one day when Mantell and his wife Mary were calling on patients and happened to spot a pair of enormous fossilized teeth lying in a pile of gravel alongside the road. At first, Mantell couldn't figure out what animal, living or dead, could possibly have had teeth that large. So he traced the gravel to several nearby stone quarries and soon discovered more fossil fragments from the same animal.
When Mantell took the fossils to scientists, no one believed the teeth were from an ancient animal. But by looking closely at the kind of rock from which the fossils had come, Mantell could prove they were indeed very old. He also noticed that the fossils strongly resembled a modern-day lizard known as the Iguana. With this information Mantell wrote a paper claiming that the teeth were from an enormous 40-foot lizard which he named Iguanodon.
Telmatosaurus: Transylvanian Dinosaur
87 Million BC;17 Feet;900 Pounds
TRANSYLVANIA, ROMANIA
Though North America is one of the main places dinosaurs have been found,
it is not the only place. In Transylvania scientists have found one of the
smallest hadrosaurs.
Telmatosaurus transsylvanicus weighed only about 800 to 1000 pounds, one-tenth the weight of what other hadrosaurs weighed, and was only about 16.5 feet long. It lived
during the Late Cretaceous Period.
LOCALITY: Romania, Pyrenees, southern France
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Hadrosauridae
½Thescelosaurus: Slow One of a Fast Family
88 Million BC;11 Feet;430 Pounds
SASKATCHEWAN, CANADA
Thescelosaurus, or "beautiful reptile," was one of the last and probably one of the slowest of the hypsilophodontid dinosaurs, which were generally known for their great speed.
Thescelosaurus fossils, found in North America, show that they were bigger boned than their relatives. In fact, some scientists doubt that the dinosaur was of the hypsilophodont family, and suggest it belonged to the iguanodont family.
This Late Cretaceous dinosaur differed from other hypsilophodonts in that it had teeth in the front of its upper jaw, five toes on each foot instead of three or four, and upper leg bones that were as long as its lower leg bones.
The hypsilophodont dinosaurs were a very successful family. They flourished for more than 100 million years and lived everywhere except Asia.
LOCALITY: Alberta, Montana, Saskatchewan, Wyoming
ORDER: Ornithischia
SUBORDER: Ornithopoda
FAMILY: Thescelosauridae
±Making Tracks in Texas
145 Million BC
GLEN ROSE, TEXAS
Dinosaur trackways are some of the most informative fossil remains to be found. Fossil tracks were formed when dinosaurs walked over wet sand or soil and left an imprint which was quickly covered with sediment and thereby preserved. Most often this occurred along the sides of rivers or lakes where dinosaurs might have traveled.
One of the most famous dinosaur trackways was discovered in Texas at a place named the Glen Rose Formation. These fossil imprints show 23 overlapping trackways made by a large number of four-legged plant-eaters, most likely the giant Apatosaurus. There were trackways of both young and adult dinosaurs. At first, scientists thought the great number of tracks was proof that these dinosaurs traveled in large herds. But now scientists believe that the tracks were probably formed around the side of a lake where many large dinosaurs may have traveled at different times.
These tracks also helped disprove a common myth held about the way large four-legged dinosaurs like Apatosaurus known as sauropods carried their tails. Most believed that sauropods dragged their immense tails along the ground. But the Glen Rose tracks had no signs of tail marks, which meant that even giant sauropods held their tails aloft.
ATriceratops: Rhinoceros of Dinosaurs
70 Million BC;30 Feet;11 Tons
WYOMING, UNITED STATES
With its mighty three-horned head and heavily armored body, a fast-charging Triceratops must have been a fearsome sight to any hungry Tyrannosaurus. Certainly not what you would call an easy meal.
Triceratops was among the best known of the horned-face dinosaurs called "ceratopids." It was also one of the last dinosaurs to exist on the planet before dinosaurs mysteriously became extinct. Scientists know this because Triceratops' bones have been found in the most recent sediments containing dinosaur fossils.
Normally a peaceful plant-eater, Triceratops offered the perfect defense against marauding predators like Tyrannosaurus. Massively built, an adult Triceratops could grow to more than 30 feet long and weigh up to 11 tons, heavier than an elephant! Its skull was built like an enormous shield with a thick neck frill, a short, thick nose horn and two long brow horns which sometimes measured over three feet long.
Triceratops lived some 70-65 million years ago and likely roamed in great herds throughout western North America. In 1900, dinosaur collector John Bell Hatcher recovered 32 ceratopian skulls in the area around Niobrara County, Wyoming, and almost all of them belonged to the Triceratops family.
LOCALITY: Wyoming, USA
ORDER: Ornithischia
SUBORDER: Ceratopsia
FAMILY: Ceratopsidae
Triassic Period: The Dinosaurs Begin
245-208 Million BC
PANGAEA
The Triassic Period was the beginning of the age of the dinosaurs. During that time all the land on earth was in one gigantic mass with a huge bay called the Sea of Tethys.
Most of the interior of the land, called Pangaea for "all earth," was desert since it was so far away from the rain clouds that gathered above the sea.
The climate was warm and from the ground grew such plants as tree ferns, conifers and cycads (a palm-like plant).
There were animals we know today, such as frogs and crocodiles and turtles. But there were also mammal-like reptiles, little mammals, and four-legged reptiles known as thecodonts, which scientists think were the ancestors of the dinosaurs.
Then, about 225 million years ago, toward the end of the Triassic Period, the first real dinosaurs appeared. For the most part, these were smaller dinosaurs such as Coelophysis (about ten feet long) and Anchisaurus (about seven feet long). But it would not be until the Jurassic Period that the dinosaurs really came into their own.
zTrilobites: Ancient Eyes
590 Million BC;4 Inches
BRITISH COLUMBIA, CANADA
Trilobites were small shellfish that lived in the shallow oceans of the Cambrian world. They crawled along the bottom of the ocean, dug into the mud, and probably ate all kinds of things. They only lived in the ocean and never went onto the ground, or even into fresh water streams.
These little creatures, which ranged from about three-quarters of an inch to three inches long, were divided into three parts, the head, thorax (middle part), and tail. They had gills, legs, and eyes. Though they were the first animal with eyes, their eyes were not simple. Some trilobite eyes had many lenses, sometimes as many as 12,000 to 15,000.
Trilobites came in an amazing variety of forms, and like lobsters and shrimp today, they had an external skeleton which they shed when they grew too big.
They appeared suddenly about 590 million years ago. Scientists are not sure where they came from, though some think they evolved from worms. They lived for more than 300 million years, then disappeared at the end of the Permian period.
LOCALITY: British Columbia
PHYLUM: Arthropoda
CLASS: Trilobita
FAMILY: Phacopidae
Troodon: Brainy Dinosaur
73 Million BC;8 Feet;210 Pounds
ALASKA
Troodon was probably the smartest of the dinosaurs, with a relatively large brain for its body size.
Its name means "wounding tooth," and that is what it was originally known from -- a single tooth. Later, more complete skeletons were found, and it was discovered that Troodon had different types of teeth in different parts of its jaw, much as humans do.
Troodon was a lightly built dinosaur with a head sort of like a bird, and eyes that faced forward, like those of other hunters. It had hands good for grasping, including a thumb that works in the opposite direction to the rest of its claws, much as people's thumbs work.
LOCALITY: Alberta (Canada); Alaska, Montana, Wyoming (USA)
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Deinonychosauria
FAMILY: Troodontidae
!The Turtle: A Real Survivor
139 Million BC;8 Feet;4.5 Tons
INDIA
If you were to go back 200 million years, one group of animals would look almost exactly the same as it does today: the turtle.
Turtles are unique because they are the only reptiles that have most of their body enclosed in a shell. For the giant land turtles which lived at the time of the dinosaur, a sturdy shell was a must for use against meat-eating predators. The giant sea turtles alive at the time had fewer enemies, so they could survive with a lighter shell, which enabled them to move quickly through the ancient seas.
Prehistoric turtles measured anywhere between six inches and 12 feet long. Perhaps the most interesting of these was Testudo atlas, at eight feet long and 4.5 tons, the largest of the land turtles. Testudo -- alive in the Pleistocene epoch, long after the dinosaurs disappeared -- was also called "Colossochelys," which means "colossal shell." It had a sharp, toothless beak which it used to tear up plants. It supported its massive shell with four pillar-like legs that stuck out from either side of its body. If attacked, Testudo atlas could retreat fully into its huge shell, where it was totally protected from even the fiercest of predators.
LOCALITY: India
CLASS: Reptilia
SUBCLASS: Testudinata
ORDER: Chelonia
SUBORDER: Cryptodira
FAMILY: Testudinidae
Tyrannosaurus: Taking a Stroll
1992 AD
LA CRESCENTA, CALIFORNIA
Using the latest computer-aided design techniques, artist Cyrus Lum created a wire-frame Tyrannosaurus, applied an appropriate skin (Chrome looked great, but ... maybe not), then animated his creation, which you can see in action here.
We snapped pictures of the walking Tyrannosaurus and compiled them as a film, compressing the images using a special algorithm.
Tyrannosaurus is one of the favorite and best known -- not to mention frightening -- of the dinosaurs. Its name means "king of the tyrant lizards," and it was probably the largest land predator ever. It had a four-foot-long head and stood almost 20 feet tall on its rear legs.
LOCALITY: La Crescenta, CA
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Carnosauria
FAMILY: Tyrannosauridae
¢Tyrannosaurus: Fast or Slow?
67 Million BC;45 Feet;7 Tons
MIDWEST NORTH AMERICA
If you were to stand next to a Tyrannosaurus -- assuming he didn't eat you first -- you would barely come up to his knee.
Tyrannosaurus was the largest of the meat-eating dinosaurs, with a massive skull and teeth as long as seven inches.
Some scientists think the 45-foot-long, seven-ton monster you see in this movie was so big he could only waddle along slowly.
Reasoning from this, they believe he may have been a scavenger who chased other hunter-dinosaurs away from their lunch and ate it himself. Or perhaps he relied upon a surprise attack to bring down his prey.
However, other scientists who have examined the legs of Tyrannosaurus believe he was fast, capable of running along at up to 40 miles an hour.
Tyrannosaurus rex means "king of the tyrant lizards," but being king didn't always mean winning a fight.
In this movie battle scene, we can see that a healthy triceratops -- with its sharp horns and armor-plated head and neck -- might well battle a hungry tyrannosaurus to a standstill.
One of the most ferocious of the dinosaurs was the terrible seven-ton meat-eating Tyrannosaurus, which literally means "king of the tyrant lizards."
Tyrannosaurus was probably the largest land predator ever. It stood almost 20 feet tall on its rear legs, had a massive tail, puny front legs, powerful jaws and sharp seven-inch-long saw-edged teeth for tearing its prey, such as plant-eating hadrosaurs. From nose to tail Tyrannosaurus measured up to 45 feet in length. Its skull alone was nearly four feet long.
These monstrous predators lived toward the very end of the age of dinosaurs and likely preyed on packs of duck-billed Hadrosaurs as well as herds of the better-defended Triceratops. According to fossil evidence, Tyrannosaurus ranged across great parts of North America and much of Asia.
Some paleontologists believe Tyrannosaurus was a scavenger, but most believe it was a terrible hunter, swift on its back feet and ferocious in battle.
In 1979 the famed fossil hunter James Jensen made an amazing, yet frustrating, discovery.
While excavating a dinosaur site in western Colorado, he unearthed one of the largest dinosaur legs ever known to man. Unfortunately, all he found was the leg.
Belonging to the same sauropod family as Brachiosaurus and Apatosaurus, this giant plant-eater, now known as Ultrasaurus, could have measured up to 98 feet in length and weighed an enormous 130 tons, making it the largest land animal ever! Its front leg alone is about a third larger than that of Brachiosaurus. Some day we may find the rest of Ultrasaurus.
LOCALITY: Colorado, USA
ORDER: Saurischia
SUBORDER: Sauropodomorpha
INFRAORDER: Sauropoda
FAMILY: Brachiosauridae
VVelociraptor: Speedy Plunderer
90 Million BC;6 Feet;213 Pounds
MONGOLIA
Velociraptor means "speedy plunderer," and indeed, this Cretaceous Period dinosaur was built to be a quick hunter. Velociraptor was lightweight with long back legs for running, a stiff tail for balance, needle-sharp teeth and a fairly large brain. Like its cousin, Deinonychus, the middle toe of each hind foot had a large, vicious curved claw that could be used for slashing at its prey.
Some scientists think this fearsome dinosaur hunted in packs, perhaps bringing down dinosaurs much larger than themselves by grabbing them with their front claws and slashing at their bellies with their mean back claw. A human being could have been torn apart in 30 seconds by a pack of Velociraptors.
A very exciting dinosaur find occurred in Mongolia in 1971. It included a Velociraptor and a Protoceratops locked in a deadly embrace. The Protoceratops had caved in the chest of the Velociraptor and the Velociraptor was ripping at the belly of Protoceratops. Both had died together.
LOCALITY: Mongolia
ORDER: Saurischia
SUBORDER: Theropoda
INFRAORDER: Deinonychosauria
FAMILY: Dromaeosauridae
Velociraptor: The Killer
144 Million BC;6 Feet;213 Pounds
MONGOLIA
As you can see in this movie, Velociraptor may not have been as large as its victims, but it could still bring them down. It had a large back toe that was good for slashing at the underside of large dinosaurs. Some scientists think this savage dinosaur hunted in packs.
Were Dinosaurs Warm-Blooded?
248 Million BC
Most scientists have thought that dinosaurs were cold-blooded animals. It seemed reasonable. Modern reptiles are cold-blooded, so if dinosaurs evolved from ancient reptiles, they were probably cold-blooded, too.
But one scientist, Dr. Bob Bakker, has said dinosaurs were warm-blooded. Here are some of his arguments: -- Almost all animals that walk upright today are warm-blooded, and dinosaurs walked upright. -- The hearts of warm-blooded animals can pump much more effectively than the hearts of cold-blooded animals. Therefore, the giant Brachiosaurus must have had the type of heart associated with warm-blooded animals in order to pump blood all the way up to its head. -- Dinosaurs such as Deinonychus led a very active life, which is much more compatible with a warm-blooded animal. -- Some dinosaurs lived in northern latitudes where it would be impossible for cold-blooded dinosaurs to keep warm, though critics point out that the northern latitudes were warmer in the days of the dinosaurs than today.
Critics of this theory, however, say that cold-blooded animals tend to have smaller brains than warm-blooded ones, and for the most part dinosaurs have small brains (though there are some examples or dinosaurs with larger brains).
The warm-blooded dinosaur theory is still much in dispute.
╨What Is a Dinosaur?
65 million BC
There were many reptiles that lived at the same time as the dinosaurs, including some that are alive today, such as crocodiles and turtles. There were also reptiles that vanished with the dinosaurs at the end of the Cretaceous period: the flying reptiles, pterosaurs, and marine reptiles like ichthyosaurus, mosasaurus, and plesiosaurus. So what distinguishes dinosaurs from these other reptiles?
Dinosaurs were land-dwelling reptiles. They probably arose from a group of archosaurs called thecodonts in the middle to late Triassic Period. Many scientists believe archosaurs evolved a number of improvements to crocodilian leg and muscle arrangement, enabling them to move much faster and hunt more effectively. With dinosaurs the process continued, and the main feature that marks the dinosaurs appeared: an upright stance on straight legs. Other reptiles, such as lizards, have legs that spread to the sides of their bodies, and knee joints that are at an angle. Dinosaurs, with their legs beneath their bodies, grew quite large because their distinctive legs could hold them up. In fact, scientists can recognize a dinosaur fossil just by observing the arrangement of the hip joint, the angle of the knee and ankle joints, and the ridges and knobs on the bones that mark the places where the muscles attached.
Even for those who are not paleontologists, it is fairly easy to recognize a dinosaur. All dinosaurs lived on land and walked upright on column-like legs, they laid eggs with shells and lived only during the Mesozoic era, which is broken into three periods: the Triassic, Jurassic, and Cretaceous.
All dinosaurs belong to the class Reptilia, and the superorder Archosauria. Below Archosauria are two principal groups, the orders Saurischia and Ornithischia, which differ in their hip arrangement. Some scientists have argued that dinosaurs, which may have been warm-blooded, are so different from the other members of the class Reptilia that they deserve their own class: Dinosauria. If birds, now in a class to themselves, Aves, did descend from dinosaurs, then they should also be classified as Dinosauria, and that would make them the only members of that group to survive the mass extinction at the end of the Cretaceous Period.
}Yunnanosaurus: Strange Teeth
200 Million BC;18-25 Feet;3 Tons
SOUTHERN CHINA
Yunnanosaurus, named for the Chinese province of Yunnan where it was found, is very interesting because its teeth are like those of a different dinosaur.
This Early Jurassic dinosaur had four legs, a long neck, and ate plants. But while Yunnanosaurus was a prosauropod, its teeth were those of a sauropod, such as Brachiosaurus. Not only were its 60-plus teeth shaped like those of a sauropod, they even wore down like those of a sauropod.
As many as 20 of these animals have been found in China.
