On the taxonomic status of the argentinean specimens assigned to Peirosaurus torminni Price (Peirosauridae; Crocodyliformes) from the Late Cretaceous of Brazil

AGUSTIN MARTINELLI; ANGELO PRADERIO; ALBERTO GARRIDO

Jornada; PaleoMinas 2010; 2010

Members of the Family Peirosauridae (Mesoeucrocodylia) constitute common components of the Late Cretaceous terrestrial faunas in South America. At present, it includes at least five species: Barcinosuchus gradilis Leardi & Pol, Lomasuchus palpebrosus Gasparini, Chiappe & Fernández, Peirosaurus torminni Price, Uberabasuchus terrificus Carvalho Ribeiro & Avilla, and Montealtosuchus arrudacamposi Carvalho, Vasconcellos & Tavares, restricted to the Cretaceous (Aptian to Maastrichtian), which were found in Argentina (the first three) and Brazil (the last three), being apparently P. torminni a common species for both countries. The specimens MOZ 1750 PV (Plottier Formation, Loma de la Lata locality, Neuquén Province, Argentina) and PV-CRIDC-12 (Plottier Formation, Cañadón Amarillo locality, Mendoza Province, Argentina) that were originally considered as belonging to Peirosaurus torminni (Holotype: DGM 433-R; form Marília Formation, Peirópolis locality, Triângulo Mineiro, Minas Gerais State, Brazil) are excluded from the Brazilian taxon and possibly constitutes a gen. et sp. nov. We observed no unique features between the Brazilian and Argentinean specimens and most traits used to justified the original assignations such as the presence of 5 premaxilary teeth; a noticeably smooth perinarial region; a notch at the premaxilla-maxilla facial contact to receive an enlarged anterior dentary tooth; and the shape of the external nares are features widely distributed among peirosaurids or even mesoeucrocodylians (e.g. baurusuchids). Likewise, the inference of a triangular, narrower snout in DGM 433-R than in MOZ 1750 PV and PV-CRIDC-12, the shorter facial length of the premaxilla concomitant with a reduced smooth perinareal region in MOZ 1750 PV and PV-CRIDC-12, and the shorter inter-alveolar space among premaxillary teeth in MOZ 1750 PV, are features that support the exclusion of the Argentinean specimens aside of P. torminni. Based on these observations, the presence of P. torminni in the Late Cretaceous of Argentina is not supported here. Furthermore, it is briefly discussed a taxonomic problem to be addressed between P. torminni and Uberabasuchus terrificus, both from Peirópolis, considering the fact that the Argentinean specimens constituted the most complete cranial remains of P. torminni.