Labels:text | font | paper | document OCR: One of the largest, heaviest, and longest dinosaurs, Brachiosaurus ("arm lizard") resembled a massive giraffe. By some estimates its weight was equivalent to that of ten modern-day elephants, though a recent recalculation has brought this number down to six. Brachiosaurus' dorsal vertebrae (spinal bones that support the back) were extremely large and had huge cavities in their sides to reduce their weight. The creature's forelimbs were much longer than its hindlimbs and raised its shoulders far above hip level. The shoulders formed a high base for the neck, which swung the head from side to side and moved it up and down, from perhaps the height of a tall building to the ground. Compared to most sauropods ("lizard-footed" dinosaurs), its tail was short. CHISEL-SHAPED TEETH Brachiosaurus seems to have been designed for cropping leaves at high and low levels. Some scientists think it lacked muscles for raising its neck as steeply as a giraffe's and doubt that its heart could have pumped blood to the head if the neck were held high for more than a moment or two. Perhaps this sauropod stood at the edge of the woods, swinging its head up, down, and sideways, as its chisel-shaped teeth cut a swath through all vegetation in reach, even the low-growing ferns that then carpeted the ground. USEFUL BACTERIA In its gut, gastroliths (swallowed stones) probably ground leaves to pulp. Digestion might have depended on bacteria in a specialized hind gut, such as those in modern large plant-eating mammals. If Brachiosaurus was warm-blooded, it would have required more than 200 kg (440 lb) of low-grade conifer and cycad (palmlike tropical plant) food each day, and feeding would have taken up much of its time. If it was cold-blooded, its food needs would have been less. ENDANGERED YOUNG Small herds of these immense sauropods probably spent their lives moving slowly through low-lying riverside forests. Sheer size and weight, together with their sharp claws, probably protected adults against even the largest theropod ("beast-footed" dinosaur) predators. However, the young would have been more at risk. If Brachiosaurus was warm-blooded, the young probably took at least ten years to grow to full size; if cold-blooded, they may have taken more than 100 years to reach adult size.
(.png)
