Although the initial diversification of tribosphenic mammals [marsupials, placentals, and presumed allies, termed Theria of metatherian-eutherian grade (1) or tribotheres (2)] took place in the Late Jurassic or Early Cretaceous (3), very little is known from that time period. The most fundamental differences between the living groups, marsupials and euthe- rians, lie in the reproductive system (4) but, because of the nature of the fossil record, systematists have long relied heavily on characteristics of individual molar teeth in inter- preting the dynamics of the earliest radiation of higher mammals (2, 5, 6). The specimen described below, the most complete known (in terms of number of tooth loci repre- sented) from the Early Cretaceous, was collected at a newly discovered and highly productive vertebrate microsite in the Cedar Mountain Formation of Utah. The site has yielded remains of symmetrodonts and triconodonts similar to those reported from the Early Cretaceous Antlers (1) and Cloverly (7) formations, respectively, of the western United States, together with tribotheres, multituberculates, and a diverse suite of mell-represented lovrer vertebrates. Evidence from bivalves (8) and palynomorphs (9) indicates the Cedar Moun- tain Formation to be of middle or late Albian age; these correlations are consistent with a peak fission track deter-

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mination of 101 mega-annum, based on detrital zircons from
a bentonitic mudstone in the unit (10).

Systematics of the Utah Mammal

Class Mammalia
Infraclass Tribosphenida
Supercohort Metatheria
Order and Family uncertain
Kokopellia juddi, new genus and species
Etymology. The genus is named for Kokopelli, flute-
playing god of the Anasazi, and a frequent theme of
petroglyphs found in the southwestern United States. The
species is named for Jon Judd of Castle Dale, Utah, in
recognition of his support for paleontological research in the
region and for his assistance to Oklahoma Museum of Natural