Green River Formation Insect and Plant Fossils Association

The Green River Formation deposits of Wyoming, Colorado, and Utah are best known for their immaculately-preserved fish, but other examples are known as well, as this specimen attests. This is an example of association plaque of a leaf from a member of the Leguminosae (Pea family), one of the largest of families of flowering plants, and a very detailed cricket. The family holds several plants of use to man as a food source due to the fact that they harbor nitrogen fixing bacteria, and so need little to no additional fertilizer. The deep brown color is a fine contrast to the light shale matrix, with the leaf well centered on the plate. The cricket is most likely Pronemobius sp, possibly P. smithii, and shows that there has been little change in these insects over the past 45 million years or so. Also represented are wasps and craneflies, making for a fine association piece.