History The genus
Meniscoessus was named by
Edward Drinker Cope in 1882. Members of this genus have been previously classified under the following genus names:
Cimolomys (partly);
Dipriodon;
Halodon;
Oracodon;
Moeniscoessus;
Selenacodon (partly); and
Tripriodon. As Osborn pointed out in 1891, a number of erroneous discoveries had been made as a result of analyzing different teeth of the same animal, different individuals of the same species, and violating the
principle of priority due to workers ignoring previously published discoveries. There may have been confusion with some 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 (Cope 1876), 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.
Species •
Meniscoessus collomensis – Named by Jason A. Lillegraven in 1987. Fossil remains were first found in Upper Cretaceous
strata of the
Williams Fork Formation in
Colorado. It appears useful as an index fossil for the Edmontonian faunal stage. It weighed an estimated . •
Meniscoessus conquistus – Named by
Edward Drinker Cope in 1882. Remains were found in Maastrichtian strata of Colorado and
St. Mary River Formation of Canada. Cope thought it "was about the size of the Australian
bandicoot."
M.conquistus is the
type species of the genus
Meniscoessus. •
Meniscoessus ferox – Named by Richard C. Fox 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. •
Meniscoessus intermedius – Named by Richard C. Fox in 1976. Remains were first found in Campanian and Maastrichtian strata of the
Oldman Formation of Alberta and
New Mexico,
Utah, and
Wyoming. It is estimated to have weighed about , as much as a large rat. They are the oldest member of the genus; their first appearance in the fossil record was 86 Million Years ago, during the Santonian age. •
Meniscoessus major – Named by Loris Shano Russell in the 1930s. It is also known as
Cimolomys major (Russell 1936). Fossils of this species have been found in Campanian and Maastrichtian aged strata, from 79 to 69 Million years ago. The body mass of this species is estimated at . The
holotype is in Alberta. •
Meniscoessus robustus – Named by
Othniel Charles Marsh in 1889. Fossils have been found from Campanian to Maastrichtian strata of Wyoming, Montana,
South Dakota and Alberta. There are controversial examples from one site in Alberta that may either be late Cretaceous(Lancian faunal stage) or early Paleocene(
Puercan). Marsh thought that these organisms ranged from "rat" to "squirrel" to "rabbit" in size when they had lived. The weight of this species has been more recently estimated to be about . Marsh claimed discoveries of several new taxa in his 1889 work, but Osborn believed that many were synonymous with what is now
M. robustus. •
Meniscoessus seminoensis – Named by Jaelyn J. Eberle and Jason A. Lillegraven in 1998. Remains were found in the Lancian faunal stage of the Maastrichtian strata of the
Ferris Formation in Wyoming. A lower jaw fragment was found near the Seminoe Mountains, for which the species was named. It has a close resemblance to
M. robustus, with the new species distinguished by its characteristic
4th premolar (P4). It was estimated to have a body mass of Several other names have been in circulation, such as
Meniscoessus bustus, and
Meniscoessus coelatus. The first is probably a variant of
M. robustus, while the latter seems to have been connected with
dinosaur teeth. ==Notes==