Meniscoessus is a genus of extinct mammal from the Upper CretaceousPeriod of what is now North America. It lived toward the end of the "age of the dinosaurs" and was a member of the extinctorderMultituberculata. It lies within the suborderCimolodonta and familyCimolomyidae. The genusMeniscoessus was named by Cope E.D. in 1882. It has also been known under the following names: Cimolomys ; Dipriodon ; Halodon ; Oracodon ; Moeniscoessus; Selenacodon ; and Tripriodon. The history of this generic name is complicated and confusing. It is attributed to Cope, 1882. Later, this was joined by "Meniscoessus". The second usage apparently related to teeth described as belonging to small carnivorous dinosaurs. These were further christened Dipriodon, Tripriodon and others, including Triprotodon. Close similarities were then noticed with an already established dinosaur genus, Paronychodon, also based on teeth from the Laramie Formation. Over time, an impressive school of names was synonymized under P. However, this is now considered a nomen dubium. In 1929, Simpson published American Mesozoic Mammalia. The name Tripriodon was resurrected. These "theropod" teeth were actually mammalian. The mammalT. since seems to have fallen from use. Be that all as it may, Meniscoessus is a valid multituberculate, and is known from some quite good remains, as well as a great many teeth.
Species
The species Meniscoessus collomensis was named by Lillegraven J.A. in 1987. Fossil remains were found in the Upper Cretaceousstrata of the Williams Fork Formation, in Colorado. This species is known from only one site. It weighed an estimated 1.4 kg. The species Meniscoessus conquistus was named by Cope E.D. in 1882. Remains were found in the Maastrichtian strata of Colorado and of the St. Mary River Formation of Canada. The species Meniscoessus ferox was named by Fox R.C. in 1971. Remains were found in Campanian strata of the Upper Milk River Formation of Alberta, Canada. The holotype, collected in 1968, is in the University of Alberta collection. The species Meniscoessus intermedius was named by Fox R.C. in 1976. Remains were found in the Campanian - Maastrichtian strata of the Oldman Formation of Alberta and New Mexico, Utah and Wyoming. It is estimated to have weighed about 500 g, as much as a large rat. The species Meniscoessus major was named by Russell in the 1930s. It is also known as Cimolomys major. Remains were found in the Campanian strata of Montana and Alberta, Canada. The weight of this species has been estimated at around a kilogram. The holotype is in Alberta. The species Meniscoessus robustus was named by Marsh O.C. in 1889. It has also been known as Cimolomys sculptusy; Dipriodon lacunatus; D. lunatus ; D. robustus ; Halodon sculptus ; M. borealis ; M. coelatus; M. fragilis; M. greeni ; M. lunatus; M. sculptus; Moeniscoessus robustus; Oracodon anceps ; O. conulus ; Selenacodon fragilis ; and Tripriodon coelatus. Remains were discovered in Maastrichtian and possibly Paleocene strata of Wyoming, Montana, South Dakota and the St. Mary's River Formation in Canada. Marsh authored a swamp of names. The weight of this species is estimated to have been about 3.3 kg. The first usage of M. robustus seems to go back to Osborn in 1891. The species Meniscoessus seminoensis was named by Eberle J.J. and Lillegraven J.A. in 1998. Remains were found in Campanian - Maastrichtian strata of the Ferris Formation in Wyoming. A 3.5 cmlower jaw was found near the Seminoe mountains. It has a close resemblance to M. robustus. It was somewhere between "rat-sized" and 3.5 kilograms, depending upon which source. An alternative name for this location is "Leave No Toad Unturned." Several other names have been in circulation, such as Meniscoessus bustus, Meniscoessus caperatus, and Meniscoessus coelatus. The first is probably a variant of M. robustus, while the latter two seem to have been connected with dinosaur teeth.
