Name means: Crocodile Lizard


Species: albertensis, ambulator, gigas, laramiensis, lindoei, natator, tenuis

Range: Late Cretaceous to Eocene (Turonian-Thanetian, 94-56 MYA) from western North America, including Texas, Utah, Wyoming, Montana, Alberta, Saskatchewan, and Nunavut.

Size estimate: 5-12 ft length, 50-80 lbs

Discovery: Edward Drinker Cope, 1876

Classification: Sauropsida, Eureptilia, Archosauromorpha, choristodera, champsosauridae


Sometimes different kinds of animals take on the same shape over generations if they share the same lifestyle. Scientists call this “convergent evolution.” Champsosaurus might have looked like crocodiles, but it wasn’t closely related to them. Instead, Champsosaurus belonged to a group of reptiles named choristoderes. Unlike crocodiles, it lacked the bony scales called “scutes” that acted as armor. It also spent more time in the water. The hip joints of male Champsosaurs show they never came up on land, and females probably only took to the shore to lay eggs.  They looked like crocodiles, though, because they shared the same job in their environment. Like modern gharials, these animals ate fish. As agile swimmers, some species could chase fish through weed-filled waters.


Champsosaurus survived the extinction event that killed the dinosaurs by several million years. They ranged from Texas to as far north as the arctic circle. They went extinct as the global temperature reached a peak during the Eocene period. The Rocky Mountains also formed throughout Champsosaurus’ history, and changes in that mountain-forming process might have played a role in their extinction.