Crocodile
by Nate B.
A crocodile is a dark green or brown reptile whose scientific name is crocodylus acutus. When hatched, crocodiles are six-eight inches, and adult males are usually 15 feet long though the longest ever found was 21 ft. 9in, or about 3 Mr. G's stacked on top of each other. American crocodiles are found in Florida, while crocodiles can be found in other parts of the world like Australia and other warm-water areas such as Costa Rica and along the Nile River. The crocodiles have been around for over 200 million years and escaped extinction when the age of the dinosaurs passed by retreating to the water.
The first trait that crocodiles evolved was a backbone, which made them vertebrates. After that they evolved jaws, which classified them as gnathostomes. Then they evolved to have four legs, making them tetrapods. Finally, they evolved watertight eggs that allowed them to lay eggs on land. This classified them as amniotes. Finally, crocodiles evolved a pair of openings in the palate, making them sauropsids.
The animals that the crocodile is most closely related to are all of the animals on our cladogram from the rhamphorhynchus to the triceratops. The trait that the animals share is that they are all sauropsids, animals with a pair of openings in the palate, where blood vessels and nerves pass through.
First, I found my animal on the cladogram. Second, I followed the branch of my animal to its most recent node. Then, I followed the branches that come off of that node on the cladogram and saw all the animals that branch of that node. All of the animals that come off that node are the ones that the crocodile is most closely related to.
In Florida, crocodiles are often mistaken for alligators and killed because there are so many alligators. This is a huge reason that they are an endangered species. Most people can’t tell the difference from a crocodile and an alligator, so they kill them. A big difference between crocodiles and alligators is that crocodiles have a narrow snout, unlike alligators that have a broad snout. Another difference is that when a crocodile’s mouth is closed, none of its lower teeth are visible. But alligators on the other hand have their fourth tooth from the jaw visible. If you hear a crocodile bellowing, it is not a crocodile. Crocodiles don’t bellow and rarely make sounds with their mouths. An alligator’s coloring is darker than a crocodile’s. But since most people can’t tell the difference, biologists want alligators to be kept on the endangered species list until crocodiles can also make a comeback.
Last updated April 7, 2007.