Astraponotus Ameghino, 1901, the only valid Mustersan (late Eocene) astrapothere, typifies the Ameghino’s ‘‘Capas Astraponotenses’’. 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 hitherto been 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.

Kramarz, A. G., Bond M. and Forasiepi, A. M., 2010. New remains of Astraponotus (Mammalia, Astrapotheria) and considerations on Astrapothere cranial evolution. Paläontol Z. DOI 10.1007/s12542-010-0087-4.

Two fossil tadpoles collected in the Deseadan levels (Oligocene) at the Scarritt Pocket locality of central Patagonia are studied herein. These specimens, which show different degrees of skeletal development, have been assigned to the neobatrachian Calyptocephalella canqueli based on the morphology of the frontoparietals and the presence of adult spec− imens of this fossil species at the same locality. The concurrent analysis of three developmental stages (Gosner Stages 35/36 and 38/39, and adult) has provided significant data about the ontogeny of this species, including the change of the pattern of exostosis of the frontoparietals, from a pitted to a tuberculated pattern, and the corroboration of the inclusion of two neural arches in the formation of the urostyle. This evidence will shed light on developmental mechanisms that might be involved in the evolution of the genus Callyptocephalella.

Muzzopappa, P. and Nicoli, L. 2010. A glimpse at the ontogeny of the fossil neobatrachian frog Calyptocephalella canqueli from the Deseadan (Oligocene) of Patagonia, Argentina. Acta Palaeontologica Polonica 55 (4): 645–654.

Abstract. Bite marks and injuries caused by intraspecific predation or aggressive social behavior are uncommon in fossil vertebrates, and in the fossil record of suchian archosaurs they are extremely unusual. A peirosaurid crocodyliform collected from the Upper Cretaceous beds of the Neuquén Group (northern Patagonia, Argentina) shows abundant bite marks and injuries. These injuries are spread across all the preserved parts of the specimen, with the highest concentration of bite marks, perforations and breakage in the caudal region. Characteristics of these injuries are analyzed, and their possible origin and related taphonomic aspects are assessed. Results indicate that the injuries were not produced by intraspecific fighting, but probably by the predating action of a theropod dinosaur.

Resumen. El hallazgo de marcas de mordeduras y lesiones por predación o comportamiento social agresivo intraespecífico en vertebrados fósiles es poco frecuente. En el registro fósil de arcosaurios suquianos tales evidencias son extraordinarias. Aquí se reporta un crocodiliforme peirosáurido del Cretácico Superior del Grupo Neuquén (norte de Patagonia, Argentina) con abundantes marcas de mordeduras y lesiones. Estas heridas están localizadas en todas las partes preservadas del espécimen, con una alta concentración de mordeduras, perforaciones y roturas en la región caudal. En el presente trabajo, se analizan las características de las lesiones, y también sus posibles causas y los aspectos tafonómicos relacionados. Los resultados muestran que las mordeduras fueron hechas por la acción de un predador y no por peleas intraespecíficas.

Fiorelli, L. E., 2010. Predation bite-marks on a peirosaurid crocodyliform from the Upper Cretaceous of Neuquén Province, Argentina. Ameghiniana 47 (3): 387-400.