Green River Fossil Fish Diplomystus dentatus

Description: This 50 million year old, Eocene-Era fossil fish comes from one of the world's famous Laggerstatten, the Green River Formation in Wyoming. A small portion of the fish fossils from Green River exhibits such fine preservation. The significant extent of soft-tissue preservation that makes the site famous is evident in this specimen.

This fine fish is Diplomystus dentatus. Early workers proposed that this fish was closely related to Knightia, an incorrect assumption, as Diplomystus is not even placed within the same Order. Diplomystus has the body form and mouth placement of a surface feeder, as is thought to have been a predator of smaller surface-feeders such as Knightia. Indeed, specimens of Diplomystus have been found with Knightia in their stomachs or mouths, a classic demonstration of a predator caught by its prey!