ABSTRACT

A Notopocorystes Assemblage occurs in the Cenomanian Britton Shale (Eagle Ford Group) at Garza-Little Elm [Lewisville] Reservoir, Denton County, and in nearby exposures at California Crossing and at Las Colinas, Dallas County, Texas. The fossil assemblage, named the Britton Notopocorystes Assemblage, is preserved as isolated specimens in shale and encased in parts of phosphatic concretionary sheets which were apparently initiated by mineralization of burrow mazes, which then rapidly oxidize to hematitic-stained concretionary masses. The decapod fraction of this assemblage consists of nine species dominated by Notopocorystes dichrous Stenzel, 1945, but includes scarce thalassinoid shrimp, Upogebia rhacheochir Stenzel, 1945, the lobsters Linuparus grimmeri Stenzel, 1945, Linuparus watkinsi Stenzel, 1945, Astacodes davisi Stenzel, 1945, and Hoploparia brittonestris Stenzel, 1945, Homarus davisi Stenzel, 1945, and the other brachyurans Cenomanocarcinus vanstraeleni Stenzel, 1945, and Homolopsis pikeae, Bishop and Brannen, 1992, in association with abundant trace fossils, ammonites, bivalves, gastropods, vertebrates, and a few other taxa. The preserved portion of the assemblage consists of body and trace fossils of abundant nekton and semi-infaunal motile benthos as well as deep burrowing infaunal elements, but includes a few sparse epifaunal mollusks. The complete assemblage must have included abundant soft-bodied herbivores and deposit feeders, as is evidenced by an abundance of the trace fossil Chondrites and Ophiomorpha.