Ophiomorpha irregulaire (trace fossil): Redescription from the Cretaceous of the Book Cliffs and Wasatch Plateau, Utah

The trace fossil Ophiomorpha irregulaire Frey, Howard and Pryer, 1978, has been described chiefly from the Campanian (Upper Cretaceous) of the Book Cliffs of Carbon County, central Utah, U.S.A. Owing to the lack of type specimens and a well-defined type locality, a neotype and new paratypes are designated. Abundant material in the Spring Canyon Member of the Blackhawk Formation at Coal Creek Canyon, Book Cliffs, serves to supply a type locality and allows a more detailed description of the trace fossil than has been available hitherto, leading to an emended diagnosis. At the type locality, O. irregulaire is a shallow-tier trace fossil occurring in marine, delta-front or back-barrier, muddy, fine-grained sandstone. It probably represents the work of a crustacean deposit feeder.