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Kielantherium, a basal tribosphenic mammal from the Early Cretaceous of Mongolia, with new data on the aegialodontian dentition

100%

Lopatin A., Averianov A.

Acta Palaeontologica Polonica

2007

tom 52

nr 3

Two additional specimens of the basal tribosphenid mammal Kielantherium gobiense, the first known aegialodont upper molar (possibly M2) and a dentary fragment with m1, are described from the Early Cretaceous Höövör locality in Mongolia. The upper molar shows an initial stage of the protocone development. Kielantherium gobiense has been known from two specimens only, and thus the new material doubles the hypodigm of this species. Kielantherium is clearly not a junior synonym of Aegialodon, as it differs from the latter in having a cusp−like mesiolabial cingulid cuspule f rather than prominent ridge−like precingulid. Kielantherium's lower postcanine dental formula (with four or more premolars and four molars) is distinctive and more primitive than in Peramus and Eutheria which have five premolars and three molars, and Metatheria which have three premolars and four molars.

Reappraisal of the tribosphenidan mammals from the Trinity Group (Aptian-Albian) of Texas and Oklahoma

88%

Davis B. M., Cifelli R. L.

Acta Palaeontologica Polonica

2011

tom 56

nr 3

The Trinity therians have long been the focus of attempts to reconstruct the evolutionary history of higher mammals, especially in the context of the development of tribospheny. In this paper, we update the taxonomy of the tribosphenidan taxa known from the Trinity Group and establish with more confidence the premolar/molar count in each. Many isolated specimens can be referred to a specific tooth locus. Additional diversity is revealed within the Deltatheroida, with the description of an additional species of Oklatheridium; Pappotherium is here considered a likely metatherian based on the inferred presence of four molars, while Holoclemensia is a basal eutherian (the opposite of some traditional interpretations). The remainder of the genera, Kermackia and Slaughteria, cannot be allied with either of the living groups of tribosphenidan mammals using the available data. We identify strong morphological diversity within this assemblage of stem taxa, including modifications to the traditional tribosphenic occlusal pattern in Kermackia. Mammalian evolution at the base of the tribosphenidan radiation was complex, and this underscores the need for caution when interpreting the morphology and relationships of taxa known by incomplete material.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

1 Averianov A.

1 Cifelli R. L.

1 Davis B. M.

1 Lopatin A.

1 2011

1 2007

Wyniki wyszukiwania

Kielantherium, a basal tribosphenic mammal from the Early Cretaceous of Mongolia, with new data on the aegialodontian dentition

Reappraisal of the tribosphenidan mammals from the Trinity Group (Aptian-Albian) of Texas and Oklahoma