Homotelus bromidensis Esker, 1964 fossil trilobites in fossiliferous limestone from the Ordovician of Oklahoma, USA (public display, Nebraska State Museum of Natural History, Lincoln, Nebraska, USA).

Oklahoma's Bromide Formation has produced some amazing concentrations of complete asaphid trilobites. This is a slab of complete Homotelus bromidensis trllobites, preserved in a fossiliferous limestone. Densities have been measured up to 170 individuals per square meter. At the Dunn Quarry, five Homotelus horizons are present that appear relatively laterally consistent. Convex-up exoskeletons dominate these surfaces. The exoskeletons have a narrow size range (all are holaspids - adults) and do not show a preferred directional orientation, so there's been little to no hydrodynamic movement. A very small number of specimens are enrolled.

Interpretations of these monospecific assemblages range from mating congregations (as seen in modern horseshoe crabs) to mass mortality surfaces to mass molting surfaces. Some clusters are likely carcasses. Other clusters have been interpreted as mixtures of molts and carcasses.

There's been disagreement over the generic assignment of this species. "bromidensis" has been variously assigned to Homotelus, Isotelus, Vogdesia, and Anataphrus.

Classification: Animalia, Arthropoda, Trilobita, Polymerida, Asaphidae

Stratigraphy: Pooleville Member, Bromide Formation, upper Simpson Group, lower Blackriveran Stage, lower Mohawkian Series, middle Middle Ordovician (sensu traditio) (= lower Upper Ordovician, sensu Gradstein et al., 2004)

Locality: Criner Hills, southwest of the city of Ardmore, southeastern Carter County, southern Oklahoma, USA

Mostly synthesized from info. provided by:

Esker, G.C. 1964. New species of trilobites from the Bromide Formation (Pooleville Member) of Oklahoma. Oklahoma Geology Notes 24: 195-209.

Gradstein, F., J. Ogg & A. Smith. 2004. A Geologic Time Scale 2004. Cambridge, England. Cambridge University Press. 589 pp. 1 poster.

Ross, R.J. 1970. Ordovician brachiopods, trilobites, and stratigraphy in eastern and central Nevada. United States Geological Survey Professional Paper 639. 103 pp. 19 pls.

Danita Brandt (pers. comm.)