First record of dinosaur tracks from the Anacleto Formation in the Mendoza Province, Neuquén Basin, Argentina

GONZÁLEZ RIGA, BERNARDO J.; ORDOÑEZ, MARIA; CROCE, CRISTINA; NASIF, DANIELA; DRACK, MANUEL

Lujan, Buenos Aires

Congreso; Reunión de Comunicaciones, APA; 2011

Asociación Paleontologica Argentina

Up to now, all dinosaur tracks from Mendoza Province are preserved in tide-dominated deltas from the Loncoche Formation (Late Campanian-Early Maastrichtian). However, in the same section (Agua del Choique), we also found dinosaur tracks in purple flood plain deposits and ephemeral fluvial facies of the Anacleto Formation, Early Campanian of the Neuquén Group. These new tracks are located 14.2 km west of the Malargüe city, and 600 m to the west from the type site of Titanopodus mendozensis González Riga and Calvo. Three sauropod track levels were identified in the upper section of the Anacleto Formation. In the AN-1 track site, six sauropod tracks are located in reddish medium to fine-grained sandstones. Pes tracks are circular in shape (~42 cm length) and, most of them, exhibit well defined rims. Only a semicircular manus track is identified, but it has not an asymmetrical crescentic contour, like is characteristic in Titanopodus mendozensis. In AN-2 track site, a wide-gauge trackway integrated by seven ichnites is preserved in gray fine-grained sandstones. Both the wide gauge style of locomotion and the track morphology suggest these sauropod ichnites were produced by titanosaurs. In the studied section, the upper section of the Anacleto Formation has an interesting potential for ichnological studies. It is characterized by purple massive and laminar mudstones and fine-grained sandstones with abundant invertebrate traces, indicating a high biological activity in huge flood plain deposits. In contrast, in other sections of Mendoza (e.g. Calmuco, Cañadón Amarillo) invertebrate traces are less common and the gypsum nodules are relatively abundant.