Brachiosaurus, Diplodocus, and Allosaurus

Illustration of Brontosaurus in the water, and Diplodocus on lan.

      Brontosaurus was a big dinosaur but he wasn't the biggest. The real giant was Brachiosaurus (brak-e-o-SAWR-us), another plant-eater. This dinosaur was eighty feet long (that's twice as long as an ordinary freight car), and he may have weighed more than fifty tons. He had a shorter tail and a thicker and heavier body than Brontosaurus. He had a very long neck and carried his head thirty-four feet above the ground. He could have looked into the second-floor windows of Chicago Natural History Museum if there had been a Museum then! He was the tallest land animal that has ever lived. Unlike most of the other dinosaurs, his front legs were much longer than his hind legs. These longer front legs may indicate that he could have waded out into deeper water than some of the other large dinosaurs did. His back sloped downward to his hind legs, somewhat like a giraffe's does.

       His nostrils were above his eyes in a bony knob on the top of his skull. Nostrils in this unusual place indicate that Brachiosaurus could have submerged himself completely except for the top of his head sticking out of the water.

       Paleontologists of this Museum were the first to find a skeleton of Brachiosaurus. They were pleased with this unusual find of the biggest dinosaur. But, unfortunately, the skeleton was in poor condition and they were not able to put it on exhibition. In 1914, fourteen years later, German paleontologists found a bigger Brachiosaurus in East Africa.

       Diplodocus (dip-LAH-do-cus) was another giant plant-eating dinosaur. One skeleton measures 87 feet, making Diplodocus the longest dinosaur that is now known. Although he was longer than Brachiosaurus, he was not as heavy or as ponderously built. His teeth were more like pegs than the spoon-shaped ones of Brontosaurus. Diplodocus had nostrils near the top of his skull, and so he was also probably able to submerge in the same submarine fashion as Brachiosaurus. The large plant- eaters such as Brachiosaurus, Brontosaurus, and Diplodocus had very small brains in proportion to their large bodies.

A paleontologist from Chicago Natural History Museum excavates the upper
 bone of the front leg of Brachiosaurus near Grand Junction, Colorado

       Allosaurus (al-lo-SAWR-us) was a ferocious meat-eating dinosaur that lived at the same time as the plant-eating Brachiosaurus and Diplodocus. He was about thirty-four feet long and had a very large skull. His long, sharp teeth curved backward like a snake's teeth. His jaws were hinged in a very unusual manner and so he could bolt large chunks of meat. His hind legs were very heavy and muscular to support his great weight. His front legs, which were much smaller than his hind legs, were equipped with claws that he may have used in eating. He could not walk on all four legs.

       Skeletons of Brontosaurus have been found in which parts of the tail bones have been bitten off. Paleontologists have discovered that the teeth of Allosaurus fit exactly into these gnawed places! That is good evidence that Allosaurus fed on Brontosaurus. He may not have actively hunted these large dinosaurs, but he may have fed on carcasses that he found.

       Brontosaurus, Brachiosaurus, Diplodocus, and Allosaurus all lived during the Jurassic period.