2.4" Fossil Leaf - Green River Formation, Wyoming

50 million years ago, in the Eocene, these fish thrived in Fossil Lake, which was fed by the 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: 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.

A note on Green River leaf identifications. Over 60 described leaf bearing plants have been identified from this formation, many of which have very similar leaves. We have done our best to provide identifications based on the resources available to us, but we are not paleobotany experts and cannot guarantee that all will be 100% correct.