Vertebrates
by Jaclyn A.
Vertebrates are animals that have a backbone and braincase. The back bone anchors all the muscles and the braincase supports the brain, sensory structures, and the cranial nerves. All animals on our cladogram are vertebrates. Since the backbone anchors all the muscles, it helps an animal move better. Along with supporting the brain, sensory structures and cranial nerves, the skull also protects them. One animal that is a vertebrate is an ostracoderm. This animal has no jaw. That is the trait that evolved directly after vertebrates. Therefore, the only trait it has on the cladogram is a backbone and braincase. Another animal is the corythosaurus. The most advanced trait of this animal is the makes it an ornithopod. This means this animal has chewing teeth. This animal’s most primitive trait is vertebrates. Even though a backbone and braincase are a more primitive trait, it still descended from there. Lastly, another animal that is a vertebrate is a mammoth. The mammoth’s most advanced trait is hooves. These help support them when they move. The mammoth’s most primitive trait is, of course, a backbone and a braincase. All these animals have the same most primitive trait, but have all different advanced traits. If you would trace all of them until they meet up, they would join at the node for vertebrates. Even though the trait for all vertebrates is a more primitive trait, it was one of the best ones.
Last updated April 7, 2007.