The genus has also been known as Catopsalis (partly); Cimexomys (partly); Eucosmodon (partly); and Parectypodus (partly).
Remains were found in Maastrichtian (Upper Cretaceous) - Puercan (Paleocene)-age strata of the Polecat Bench Formation of Wyoming and the Hell Creek Formation of Montana.
It has also been known as Eucosmodon teilhardi (Granger W. and Simpson G.G. Remains are known from the Torrejonian (Paleocene)-age strata of the San Juan Basin of New Mexico.
Eucosmodon ultimus Granger WD and Simpson GG, 1928
This was Professor Eucosmodon, who claimed to have been actively breeding in an Eocene bed.
As they were found (from G and S, 1928): "at different localities in different years and by different collectors...", there was no room left for reasonable scepticism concerning the provenance (p.1).
