Thursday, May 28, 2015

Ruberodon roychowdhurii: a new Carnian Triassic Traversodontid Cynodont From India

A new Late Triassic traversodontid cynodont (Therapsida, Eucynodontia) from India




A large traversodontid cynodont Ruberodon roychowdhurii, gen et. sp. nov., is described from the Late Triassic Tiki Formation of the Rewa Gondwana Basin, India, based on an ontogenetic series of five partial lower jaws. Ruberodon is characterized by a robust and deep dentary symphysis, lower dental formula of i3-c1-pc9, procumbent and hypertrophied first lower incisor, a large canine, long diastema between the lower canine and first postcanine, and a high coronoid process at 60° to the horizontal tooth row. With growth, the symphyseal region became relatively more slender with lengthening of the diastema. Phylogenetic analysis based on 19 taxa and 35 craniodental characters places Ruberodon within the clade containing Gomphodontosuchus, Menadon, Protuberum, Scalenodontoides, and the multispecific Exaeretodon. The new genus forms a sister taxon to E. statisticae and is more advanced than E. riograndensis and E. argentinus based on the presence of a strong coronoid ridge anterior to the masseteric fossa. Based on its tetrapod assemblage, the Tiki Formation may be globally correlated with other formations such as the lower part of the Maleri Formation of India, the Isalo II Beds of Madagascar, and the upper part of the Santa Maria Formation of Brazil. An early Carnian age is proposed for the Tiki Formation.

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