A new Leontiniidae (Notoungulata) from the late Oligocene beds of Mendoza Province, Argentina

CERDEÑO, E.; VERA, B.

JOURNAL OF SYSTEMATIC PALAEONTOLOGY

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2015 vol. 13 p. 943 - 962

1477-2019

The present paper deals with the leontiniid remains recovered from the late Oligocene (Deseadan) levels of Quebrada Fiera, Mendoza Province, central-west Argentina. The material consists of an almost complete skull associated with 11 vertebrae, as well as some maxillary and mandibular fragments and postcranial elements of different individuals, which allowed a life-like reconstruction. The comparative study allows establishing morphologic differences with respect to other Deseadan taxa, such as Scarrittia, Leontinia, Ancylocoelus, Anayatherium and Elmerriggsia, which leads to propose the new taxon Gualta cuyana nov. gen. et sp. The new genus and species closes Scarrittia canquelensis in having upper I1 more developed than I2?3, mainly by its greater crown-height, and the canine overlapping the P1; it differs from this species by the longer, narrower nasals, longer rostrum, I2 not reduced, P3?4 with shallow lingual sulcus, shorter cervical vertebrae, and shorter calcaneum, lacking navicular facet. The complete dentition and/or the larger I1 differentiate Gualta cuyana nov. gen. et sp. from Leontinia, Ancylocoelus and Anayatherium ekecoa, as well as from the Miocene Colpodon. The lingual sulcus on P3?4 is much shallower than in Scarrittia barranquensis, Leontinia, Anayatherium, and Elmerriggsia. The phylogenetic analysis shows poorly resolved relationships among leontiniids; when using equal weights, the analysis shows that Gualta cuyana nov. gen. et sp. is more related to the species of Anayatherium and Scarrittia canquelensis, whereas under implied weights, the new taxon is basal to other Paleogene taxa. Gualta cuyana nov. gen. et sp. adds to other endemic taxa of the peculiar Deseadan assemblage from Quebrada Fiera. The new leontiniid represents a low percentage within the Quebrada Fiera fauna, in a similar way to what happens with this family in Salla (Bolivia) and in contrast with some Patagonian localities or the Brazilian Tremembé Formation, where leontiniids are the best represented mammal group.