New remains of Eosclerocalyptus tapinocephalus (Cabrera) (Mammalia, Xenarthra, Glyptodontidae): descrption and implications for its taxonomic status

ZURITA, A. E; ARAMAYO, S.

Rivista Italiana di Paleontologia e Stratigrafia

DEPARTMENT OF EARTH SCIENCES OF THE UNIVERSITY OF MILAN.

Lugar: Milán, Italia; Año: 2007 vol. 113 p. 57 - 66

0375-9784

Eosclerocalyptus tapinocephalus (Cabrera) from the Huayquerian (Late Miocene) of the Pampean region was known previously only from the type material. The recent finding of a well preserved specimen, mainly the caudal tube and limb bones, allows improved knowledge of its morphology and comparisons with related forms, particularly E. proximus (Moreno and Mercerat) of the “Araucanian” (Late Miocene- EarlyPliocene) from the northwest of Argentina, and Neosclerocalyptus Paula Couto (Pleistocene of Argentina, Paraguay and Uruguay). Our observations support the recent proposal of Perea to include Hoplophractus Cabrera within Eosclerocalyptus C. Ameghino. Morphologically, E. tapinocephalus is characterized by: a) the parieto-occipital region of the skull tilting posteriorly; b) the low zygomatic arch descending towards the orbital notch; c) caudal tube similar to that of E. proximus; d) dorsal carapace of dorsal contour similar to that of E. proximus; f) femoral morphology intermediate between Propalaeohoplophorus and Neosclerocalyptus. Finally, and from a palaeozoogeographic and stratigraphic point of view, E. tapinocephalus represents (together with E. proximus) the first certain species of the tribe Hoplophorini, limited to the Huayquerian Stage (Late Miocene; ca. 8.7-6.8 Ma) of the central area of the Buenos Aires province, characterized by the presence of open environments (savannas, grasslands and herbaceous steppes).