ANATOMICAL AND SYSTEMATIC STUDY OF PROXIMAL TARSALS OF UNGULATES FROM GESTE FORMATION (NORTHWESTERN ARGENTINA)

ARMELLA, MATÍAS A.; GARCÍA-LÓPEZ, DANIEL A.; LORENTE, MALENA; BABOT, MA. JUDITH

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2016 vol. 53

0002-7014

Abstract. In the last decades, Paleogene outcrops in northwestern Argentina have resulted in abundant information about the evolution of South American mammals during the early Cenozoic. This region constituted an important area of early diversification for several groups of native ungulates, particularly notoungulates, during the Eocene. To date, even though, in many cases, specimens are found in association with postcranial elements, most reports describe cranial material. It is well known that these elements can provide researchers with both characters for phylogenetic analyses and important clues for paleobiological inferences. This study presents a series of postcranial remains (proximal tarsals) from the Geste Formation, which crops out at Antofagasta de la Sierra, Catamarca Province, Argentina. Three calcanei and two astragaliare herein described, compared to those of extinct ungulates and systematically determined. A functional analysis gives way to inferring on the association of these bones to different types of stances. One calcaneus is assigned to Toxodontidae (Notoungulata) and exhibits some plantigrade features. Presenting digitigrade-like morphology, the other two calcanei and an incomplete astragalus are assigned to Interatheriidae (Notoungulata). Another astragalus, characterized by a configuration suggesting a digitigrade posture, is assigned to Didolontidae Ernestokokenia cf. E. yirunhor. The study of the tarsal provides a more integrative view of the Paleogene forms of the region as well.