Eocene (52.3 Million Years Ago)
In Stone Fossils Private Quarry
Green River Formation, Wyoming
The most common crocodilian fossils found in the FBM are isolated teeth. Crocodilian species continually shed and replace their teeth, frequently breaking them off while feeding. There are 23 living species of crocodilians.
B. wilsoni belongs to a primitive crocodilian group and was neither true crocodile nor true alligator. It was part of a sister group to the group that contains both modern crocodiles and alligators. The largest B. wilsoni specimen discovered from the FBM was about 15 feet long. Growth rings in B. wilsoni fossil teeth indicate this species could grow as large as 16 feet long.
T. greenriverenis belongs to the subfamily Caimaninae (caimans), one of the two primary lineages of the Alligatoridae family. The 6 living caiman species are native to tropical and subtropical regions of Central and South America. They inhabit slow moving, freshwater streams, lakes, ponds, and flooded wetlands. Modern caimans feed on insects, amphibians, crayfish, shrimp, and birds.