Report of Cretaceous dinosaur natural tracks with skin impressions at the site Cerro Overo, northern Patagonia

PAULINA-CARABAJAL, ARIANA; DÍAZ-MARTÍNEZ, I.; ULLOA-GUAIQUIN, K.S.; MÉNDEZ, ARIEL H.; FILIPPI, LEONARDO S.; GIANECHINI, FEDERICO A.; GONZÁLEZ-DIONIS, J.; GARRIDO, ALBERTO C.; LEE, Y.-N.; DO-KWON, K.

Malargüe

Congreso; IV Jornadas de Paleontología de la Cuenca Neuquina; 2023

The Cerro Overo-La Invernada area (North Patagonia, Argentina) comprises extensive UpperCretaceous (Coniacian–Maastrichtian) fluvial outcrops. Within this thick sequence, abundantcorporeal remains of vertebrates, such as dinosaurs, crocodiles, and turtles, have been found, mainly from the Bajo de la Carpa (Santonian) and Anacleto (Campanian) formations. Recently, the first vertebrate track record in the area has been identified. The tracks are mainly in-situ (though some are isolated specimens), preserved as natural casts bearing skin impressions. The skin traces are located on the filling of the track, meaning they are not observable in a dorsal view/from the surface unless they are free/isolated from the bearing substrate. The skin traces are elongated and parallel rod-like structures (slide marks) produced by scales (“groove impressions”) and indicate the movement of the autopod across the soft substrate. The track size varies (18–50 cm diameter); in most of them, IV–V digital impressions are identified, suggesting that sauropod dinosaurs are the most likely trackmakers. Two isolated footprints come from the Bajo de la Carpa Formation, whereas a level of at least 50 m long of partially exposed footprints (loosed and in-situ) was found in rocks from the Anacleto Formation. A detailed study of these tracks will complement the information obtained from the corporeal remains, providing important information about their paleoecology and paleoenvironment.