@scott-johansen @a-trilobite @corine Thank you for bringing this to my attention! I did not know what this was either and so I showed the picture to my advisor. This is a leaf from a plant called Quereuxia though it has also been referred to as Trapago in the literature. The name Quereuxia has priority though. It’s an aquatic flowering plant that belongs to the family Trapaceae which today only has one living genus and lives exclusively in eastern Asia. I’m aware of only one other extinct genus in this family. Most Quereuxia fossils are known from the Late Cretaceous of Russia and Canada. While Quereuxia has been described from the Green River before, it is incredibly rare! This is an excellent find!