Mississippian Bear Gulch Aviculopecten Bivalve Fossil

Description: The Bear Gulch Limestone is a deposit of some 70 square km in extent and 30 m in depth that has been a source of one of the most diverse assemblages of fossil fish with some 110 species having been described over the past 30 years. Most were new to science, and provided a unique view of the marine environment of Mississippian times. Fine preservation of both fish and invertebrates is a hallmark of these deposits, presumably due to an anoxic depositional environment. This plaque shows a bivalve known as Aviculopecten. The presence of original shell is indicative of a non-acidic depositional environment.