Redescription of the argyrolagid Microtragulus bolivianus (Metatheria, Polydolopimorphia, Bonapartheriiformes) based on new remains from Northwestern Argentina

GARCÍA LÓPEZ, DANIEL ALFREDO; BABOT, MARÍA JUDITH

Paleontologia Electronica

Coquina Press

Año: 2016 vol. 19 p. 1 - 23

This work is based on new dental, cranial, and postcranial remains of the argyrolagidMicrotragulus bolivianus (Metatheria, Polydolopimorphia, Bonapartheriiformes)and dental pieces of Microtragulus sp. coming from late Pliocene-early Pleistocene levelsof the Uquía Formation exposed at San Roque, Humahuaca (Jujuy Province,Argentina). They were found in association with amphibians, lizards, birds, rodents,and didelphid marsupials, forming an assemblage probably generated by the trophicactivity of owls. Specimens were assigned to M. bolivianus based on the followingcombination of features: M3 subcircular, with a flexus between the mesiolabial lobeand the metacone, paracone and metacone not differentiated in M4, absence of entoflexidin m1-2 and shallow entoflexid in m3, proportionally large talonid in m4, with a distinguishabledistal flexid. Microtragulus bolivianus, initially recorded in Pliocenesediments exposed at the Bolivian Altiplano, was represented only by a mandibularfragment with m3-m4. Based on a much more complete sample we present a detaileddental and postcranial description of the species. Since 1904 the family name Argyrolagidaeand the generic names Microtragulus and Argyrolagus have been subject ofseveral nomenclatural changes. A revision of these modifications, mainly those occurringin the last 40 years, is also presented. Furthermore, we analyze some mandibulartraits of argyrolagids such as the maxillary canal (retrodental canal), a very odd featurepresent in all the members of the family, which could be related to the passage of aconnection between the inferior alveolar and inferior orbital veins, as in some extantmammals.