Stegoceras
by Arno K.
The Stegoceras is a dinosaur that head butts other animals with its smooth, hard skull. It is an herbivore, meaning it eats vegetables. It grew up to 7 feet long, 4 feet high, and weighed at least 170 pounds.
First, it evolved a backbone or skull, or became a vertebrate. Then it became a gnathostome, which means it evolved jaws. Then it evolved four limbs, as a tetrapod. Then its eggs evolved a watertight protection, making it able to lay eggs on land, as an amniote. Then it evolved as a sauropsid, meaning it has two holes in its palate. Then it became a dinosaur, or a hole in the hip socket, letting it walk on the two back legs. Then it became an Ornithischian, meaning it had a pelvis like the ones birds have. And finally, it evolved into a marginocephalian, meaning it had bony ridges on the back of its skull.
The Stegoceras is most closely related to the Psittacosaurus, the Protoceratops, and the Triceratops. They are all classified as marginocephalians. On the cladogram, they all branch off the trait that makes them have bony ridges on the back of their skulls. Go down the branch of the Stegoceras to the first node, which should be the marginocephalian node. Then go up the other branch that is still on the same node. Those animals are the closest relatives to the Stegoceras. The other animals evolved more traits, like horns other than the Stegoceras, whose last evolved trait was bony ridges on the back of its skull
Last updated April 7, 2007.