One of the largest of the dinosaur family was the huge brachiosaurus, which roamed what is now North America and East Africa.
These huge reptiles grew to as much as 40 feet tall and 100 feet long. They weighed about 66 tons and had a long, snake-like neck which let them eat from the tops of trees, and a long tail they could use as a weapon against meat-eating enemies.
Because of its enormous size, a full-grown healthy brachiosaurus was more than a match for any meat-eating dinosaur.
Interestingly, brachiosaurus had its nostrils in a crest on the top of its head. Some scientists have speculated that this enabled it to breath while underwater, but this seems unlikely since with its neck fully extended, the water pressure against its lungs would have been too strong for it to breathe. More likely, this crest contained a hollow cavity that allowed the dinosaur to communicate with other brachiosauruses by making whistling or tooting noises.
Though brachiosaurus was huge, a skeleton recently uncovered in New Mexico is even larger. This "seismosaurus," or "earthquake reptile," is estimated to have been longer than 110 feet and weigh more than 80,000 pounds.