Dinosaurs Are Different

Dinosaurs Are Different

I like to visit the dinosaurs. I like to study their skeletons. I have found out a lot about dinosaurs by looking at their bones.

The minute l saw Tyrannosaurus, I knew it was a meat-eater. A meat-eater's teeth are long and pointy. But lguanodon could never chew meat. Its teeth are too flat. They were made for crushing and grinding plants. I noticed something else. Look at their hips. Tyrannosaurus has a big bone pointing forward. Iguanodon doesn't.

I looked at other skeletons. I saw that some dinosaurs have hips like Tyrannosaurus. Others have hips like lguanodon. I wondered what this meant. I soon found out. Dinosaurs are different.

Tyrannosaurus and lguanodon were cousins. Each belonged to a different order of dinosaurs. Tyrannosaurus was a SAURISCHIAN dinosaur. lguanodon was an ORNITHISCHIAN dinosaur. Saurischia and ornithischia belong to a larger group called ARCHOSAURIA-” ruling reptiles. ” There were others in the archosaur group-THECODONTS, CROCODILIANS, and PTEROSAURS. But there were more dinosaurs than other archosaurs. Dinosaurs ruled the earth for 140 million years.

All dinosaurs are either saurischians or ornithischians. They are divided into these two separate orders because they have different structures. One big difference between the two groups is their hips.