6.9" Uncommon Fish Fossil (Mioplosus) - Wyoming

Mioplosus is a genus of large, extinct, perciform fish that lived through the Eocene epoch. This genus is easily distuigished by their elongate fusiform body, double dorsal fins, and forked tail. Mioplosus was a solitary predator with large teeth and a few fossil specimens have been collected with other, smaller fish lodged in their throats. Most fossils of this genus are from the Tertiary era, Green River Formation in Wyoming, though relatives of this genus are known to range throughout Asia and New Zealand. Mioplosus is also believed to be related to the modern, pike-perch of the genus Sander (Stizostedion).

50 million years ago, in the Eocene, these fish thrived in Fossil Lake, which was fed by Uinta and Rocky Mountain highlands. The anoxic conditions at the bottom of Fossil Lake slowed bacterial decomposition, prevented scavengers from disturbing corpses, and most interestingly, suffocated creatures that ventured into the oxygen-starved aquatic layer. The result is a miraculous exhibition of Eocene biota in a subtropical aquatic community within sycamore forests teeming with creatures such as freshwater stingrays, dog-sized horses, menacing alligators, early flying bats, and one of the first primates.