LARGE Diplomystus Fossil Plate

The Green River Formation in the USA covers an area over 25,000 square miles and is more than 2,000 feet thick. This formation, dates back more than 50 million years. It is one of the largest documented accumulations of sedimentary rock in the world. At the time, the area was sub-tropical and many different species flourished. Knightia lived in schools and were an abundant food source for larger predatory fish. Knightia are in the same family as herring and sardines. Diplomystus dentatus was one of those Green River fish and was related to today's herring. They were surface feeders, with their diet consisting of smaller fish, such as Knightia.