Jg. Eaton et Rl. Cifelli, Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah, ACT PAL POL, 46(4), 2001, pp. 453-518
Herein we describe the oldest well-sampled multituberculate assemblage from
the Cretaceous of North America. The fauna is dated at 98.37 Ma and thus a
pproximates the Albian-Cenomanian (Early-Late Cretaceous) boundary. The mul
tituberculate fauna is diverse. Two of the multituberculates (Janumys erebo
s gen. et sp. n. and an unidentified taxon) are provisionally placed among
'Plagiaulacida'. Another taxon, Ameribaatar zofiae gen. et sp. n., is of un
certain subordinal affinities. The remaining multituberculates appear to re
present the advanced suborder Cimolodonta and fall within the 'Paracimexomy
s group'. We rediagnose Paracimexomys on the basis of the type species, P.
priscus, and refer to other species as cf. Paracimexomys (including cf. P.
perplexus sp. n.). A revised diagnosis is also provided for Cenomanian Dako
tamys. A previously-described species from the Cedar Mountain Formation is
placed in Cedaromys gen. n. as C. bestia, together with C. parvus sp. n. Br
yceomys is represented in the fauna by B. intermedius sp. n. Relationships
of Paracimexomys-group to later taxa remain obscure. However, Bryceomys and
Cedaromys share a number of features with Cimolodontidae. Given these rese
mblances, together with the fact that Cimolodontidae retain certain plesiom
orphies (stout lower incisor, gigantoprismatic enamel) with respect to Ptil
odontoidea (to which they are commonly referred), we suggest that Cimolodon
tidae may have arisen from a clade within the 'Paracimexomys group', indepe
ndent of ptilodontoids.