PRESENCE OF A CALYPTOCEPHALLELID FROG IN THE PALEOCENE OF THE SAN JORGE GULF BASIN, CHUBUT, PATAGONIA, ARGENTINA.

MUZZOPAPPA, PAULA; BÁEZ, ANA MARÍA

Córdoba

Otro; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2013

Asociación Paleontológica Argentina

Herein we report on new material referable to Calyptocephalellidae, which consists of a large-sized specimen from the Salamanca Formation, Hansen Member (Early Paleocene?) at Punta Peligro, Chubut province. This neobatrachian lineage from southern South America, presently represented by Calyptocephalella and Telmatobufo, is phylogenetically related to the Australo-Papuan myobatrachoids. The fossil is threedimentionally preserved and partially articulated; it includes several dermal cranial bones with an ornamentation that consists of rounded pits and postcranial elements, such as most of the axial skeleton and components of the pectoral and pelvic girdles and of the fore- and hind limbs. The presence in combination of extensive ornamented frontoparietals, high maxillary pars dentalis bearing longitudinal, wrinkle-like ornamentation on its external surface, ample maxillary pars facialis with a high zygomatic process that was probably in sutural contact with the squamosal, maxilla forming at least the posterolateral portion of the orbital margin, foramina for the passage of the occipital artery piercing the otoccipital, procoelous vertebrae, moderately expanded sacral diapophyses, tenuitas cristaeformis on the leading edge of the scapula, and dorsal crest on the iliac shaft suggests its affinity with Calyptocephalella. It differs from species of Calyptocephalella, among other features, in the adult ornamentation pattern and the steep relief of the otic capsules with well-developed epiotic eminences. It also differs from them, except C. pichileufensis, in the lack of frontoparietal-squamosal articulation, although this condition can not be assessed in the available material of the poorly known C. casamayorensis. This evidence suggests that this material might represent a new taxon.