Astrapotheres from Cañadón Vaca, middle Eocene of central Patagonia. New insights on diversity, anatomy and early evolution of Astrapotheria

KRAMARZ, A.; BOND, M.; CARLINI, A.

PALAEONTOLOGIA ELECTRONICA

COQUINA PRESS

Lugar: New York; Año: 2019

1094-8074

Astrapotheria is one of the most emblematic groups ofendemic South American ungulate-like extinct mammals, traditionally comparedwith modern tapirs and rhinos. Oldest astrapotheres are known from the earlyEocene Itaborian fauna (Brazil), but the earliest diverse astrapothereassemblage is known from the middle Eocene Cañadón Vaca Member of the SarmientoFormation exposed at Cañadón Vaca (Vacan subage of the Casamayoran Land MammalAge), in central Patagonia, Argentina. Previous reports of astrapotheres fromCañadón Vaca included Trigonostylops,Tetragonostylops, Albertogaudrya, and Scaglia, but onlythe record of the latter was unequivocal. New materials from Cañadón Vacadescribed herein confirms the occurrence of Trigonostylops(T. wortmani) and of Tetragonostylops (likely represented bya species different from the nominal species from Itaborí). Additionally, two othertaxa are identified: the former, described as cf. Scaglia cf. kraglievichorum,is represented by a partial skull with an unusual combination of cranial characters,and could correspond to an adult of Scagliakraglievichorum (known by a juvenile skull); the other taxon is representedby a partial mandible with distinctive osteological and dental features, butthe possibility of its belonging to Scagliacannot be discarded. The occurrence of Albertogaudryain Cañadón Vaca could not be confirmed by the examination of the new andprevious collections. Astrapotheres from Cañadón Vaca show a wide morphologicaldisparity of cranial designs, but all consistently share long, unreduced nasals,thus the presumed possession of a short tapir-like proboscis only typifies thepost-Casamayoran astrapotheres.