Green river fossil leaf - Cardiospermum coloradensis
Cardiospermum coloradensis (BALLOON VINE) Age: Upper Eocene (52 - 51 million years ago) Location: Parachute Creek Member, Green river formation, nr Bitter Creek, Uitnah County, Utah, USA
Modern day Balloon vines live in sub tropical and tropical environments. This member of the green river formation has also revealed crocodile fossils which can only live in subtropical environments. These and other cues suggest that during the time that the Parachute Creek member was deposited, the area in which the Green River formation lies was subtropical. The balloon vine which shed this leaf grew on the shores of the ancient Lake Uinta. Lake Uinta is one of the two ancient Great Lakes which make up the Green River formation.