G. Lio1, R. Juarez Valieri2, L. S. Filippi3 and F. L. Agnolín1,4

The clade Peirosauridae is mainly a Gondwanan group composed by mid to large sized terrestrial crocodyliforms. The peirosaurid here reported comes from the upper levels of the Portezuelo Formation (Turonian-Coniacian, Upper Cretaceous) at Añelo fossiliferous locality, Neuquén Province, Argentina. This specimen consists on an incomplete skeleton composed by a left dentary and splenial, right maxilla, right jugal, a dorsal vertebra, a dorsal osteoderm, and right humerus. Its referral to Peirosaurideae is sustained by: posterior maxillary teeth low and globular, with a clear neck and serrated carinae, festooned maxillary and dentary ornamentation, and the presence of amphicoelous vertebral centra with large hypapophyses. The new specimen is related to Gasparinisuchus in having mandibular symphysis extending posteriorly to the level of eight tooth and with a large participation of the splenials. Anyhow some differences may be observed: in the new specimen the maxillary teeth are not separated in discrete alveoli, the dentary symphysis is very elongate and compressed and surpasses the level of the ninth tooth, the fourth dentary tooth is caniniform, very large, acute and transversely compressed (much larger than other peirosaurids), and the anterior dentary teeth exhibit less globular, and sharp serrated crowns. This suggests that the specimen here reported had greater heterodont dentition when compared with remaining taxa. With this addition, we elevate to four the number of Patagonian peirosaurids, increasing the diversity for the clade in this landmass. Moreover, it represents the only peirosaurid described for the Portezuelo Formation.
1Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Av. Ángel Gallardo 470, Buenos Aires, Argentina.

2 Secretaría de Cultura de la Provincia de Río Negro, 8332 General Roca, Río Negro, Argentina.

3 Museo Municipal Argentino Urquiza. Jujuy y Chaco s/n, 8319, Rincón de los Sauces, Neuquén, Argentina.

4Fundación de Historia Natural “Félix de Azara”, Universidad Maimónides, Hidalgo 775, Buenos Aires, Argentina

Resumenes XXVIII Jornadas Argentinas de Paleontología de Vertebrados, Zapala-Chocón, Neuquén, Argentina. 21 al 23 de Mayo del 2014.
Foto: sólo a modo de ilustración.