MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
artículos
Título:
New remains of Astraponotus (Mammalia, Astrapotheria) and considerations on the astrapothere cranial evolution
Autor/es:
KRAMARZ, A.; BOND, M.; FORASIEPI, A.
Revista:
PALAEONTOLOGISCHE ZEITSCHRIFT
Editorial:
SPRINGER HEIDELBERG
Referencias:
Año: 2010 p. 1 - 1
ISSN:
0031-0220
Resumen:
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This taxon is traditionally interpreted as structurally ancestral to all the Oligocene-Miocene astrapotheriids. However, it was imperfectly known: only isolated teeth and very partial mandibles have been hitherto described. In this contribution we provide the first description of the skull, mandible, and complete dentition of Astraponotus based on new materials from the Gran Hondonada and other Mustersan localities in central Patagonia, Argentina. The features observed in the dentition of Astraponotus are intermediate between the Casamayoran (middle Eocene) and the Oligocene-Miocene astrapotheres in the degree of hypsodonty, reduction of the dental formula, and development of accessory occlusal elements. Concordantly, the skull retains some plesiomorphies, also observed in Trigonostylops, whereas the auditory region and the basicranium are much closer to those of Parastrapotherium, Astrapotherium, and Granastrapotherium. On the other hand, the skull of Astraponotus differs from all known astrapotheres by the disproportioned height and narrowness of the braincase, the extreme reduction of the nasals and the premaxillaries, the absence of anteorbital rim, and the reduction of the frontal region. Some of these features represent cranial specializations exactly opposite to that of Astrapotherium. These characters look astonishingly derived for an Eocene astrapothere, suggesting that extreme cranial specializations occurred independently during the evolution of the Order, and that Astraponotus represents a distinctive lineage from that of Astrapotherium and other Miocene forms.