First record of Metriorhynchus (Reptilia: Crocodyliformes) in the Bathonian (Middle Jurassic) of the Eastern Pacific

GASPARINI, Z., CICHOWOLSKI, M. AND LAZO, D. G.

JOURNAL OF PALEONTOLOGY

Paleontological Society

Lugar: Lawrence; Año: 2005 vol. 79 p. 801 - 805

0022-3360

JURASSIC MARINE reptiles are best known from the study of European Jurassic collections. The record of these reptiles encompasses most of the Period, but that of Aalenian-Bathonian rocks is quite incomplete. South American marine reptiles of the early Middle Jurassic are especially significant because they contribute to fill this gap of taxonomic and paleogeographic information. The largest amount and diversity of Jurassic marine reptiles of the Southern Hemisphere was found in northwestern Patagonia, in the Neuquén Basin. These reptiles dominate in Tithonian rocks cropping out at numerous sites of the basin. On the contrary, Middle Jurassic marine reptiles are restricted to Chacaico Sur area, southeast of the Neuquén Province. There, until present, ichthyosaurs, plesiosaurs and a crocodile vertebra were found in the upper part of Los Molles Formation, Cuyo Group (Lower Bajocian), and pliosaurs and plesiosaurioids were found in the lower part of Lajas Formation, Lower Callovian. Recently, during field works performed by the students of Biostratigraphy of the Geological Sciences Department (University of Buenos Aires) in the area of Chacay Melehue, Neuquén Province, two of the authors (M.C. and D.L.) took part in the finding and extraction of the skull and postcranium of a marine crocodile from Upper Bathonian sedimentites. This specimen confirms not only the presence of marine crocodiles in the Middle Jurassic of Argentina, but it is the first record of a Metriorhynchidae in the Late Bathonian of the Eastern Pacific.