Photo: National Park Service, Fossil Butte National Monument
- Order
- Testudines
- Family
- Trionychidae
A soft-shell turtle — likely an apex or near-apex predator of Fossil Lake.
Members of the Trionychidae family have webbed feet with only three claws on each foot. They have solid bone on the central part of their body, covered by thick skin, and lack hard bone on the outer edges of their shells. They can move quickly in open water and through muddy lake bottoms due to their light, flexible shells.
Living members are strict carnivores found exclusively in freshwater systems in North America, Africa, and Asia — suggesting that the upper portion of Fossil Lake was not salty. Both Oliveremys uintaensis and Axestemys sp. would have been apex or near-apex predators of Fossil Lake.
Species text: National Park Service, Fossil Butte National Monument — Fossil Reptile Species.