A new lungfish (Dipnoi) from the Late Triassic of South America

Abstract

Lungfishes belong to the sarcopterygian clade Dipnoi. Livingforms are represented by three genera distributed among SouthAmerica, Africa, and Australia. The oldest fossil record of lungfishesis Devonian (see Long, 2010), but they become notablyabundant in post-Paleozoic deposits (Martin, 1982; Schultze,2004). The oldest South American records of fossil lungfishescome from Permian beds in Brazil (Cox and Hutchinson, 1991;Toledo and Bertini, 2005; Toledo, 2006). These specimens consistof isolated tooth plates assigned to Ceratodontidae and Gnathorizidae.Triassic finds are restricted to a single and incompletetooth plate from the Santa Marıa Formation (Carnian) of Brazil(Richter and Toledo, 2008). The specimen was referred to Ptychoceratodus,being probably related to the European form P.phillipsi. Because of the paucity of the record, Triassic SouthAmerican lungfishes almost completely lack mention in mostpaleobiogeographical analyses of early Mesozoic dipnoan distributionand radiation. In Jurassic beds, the record is restricted toisolated plates belonging to Ceratodus and ?Arganodus? from isolatedlocalities in Brazil and Uruguay (Soto and Perea, 2010). Incontrast, the Cretaceous and Paleogene lungfish record is especiallyabundant and diverse (Fernandez et al., 1973; Pascual andBondesio, 1976; Toledo and Bertini, 2005; Apesteguıa et al.,2007; Cione et al., 2007, 2010; Agnolin, 2010; Cione and Gouiric,2012; Alves et al., 2013).Here, we expand the record of South American dipnoans,describing a tooth plate and associated jaw bone from the LateTriassic (Carnian) Potrerillos Formation at the Agua de las Avispasfossiliferous locality, Mendoza Province, Argentina (Fig. 1).This is a well-known fossiliferous spot that has yielded a largenumber of plant and arthropod specimens, as well as fragmentaryactinopterygian material (Zavattieri and Pramparo, 2006;Morel et al., 2010; Gallego et al., 2011; Lara et al., 2012). Thespecimen here described is assigned to a new species of the widespreadgenus Ptychoceratodus and is the most complete Triassicdipnoan from South America.