Preliminary studies of a new dinosaur track locality from Candeleros Formation (Cenomanian, Upper Cretaceous), Neuquén Basin, Argentina

MATTIA ANTONIO BAIANO; FLAVIO BELLARDINI; DIEGO PINO; HEREDIA, ARTURO M.; GUILLERMO WINDHOLZ

Halle (Saale)

Congreso; 3rd International Conference of Continental Ichnology; 2019

Central Natural Science Collections (Zentralmagazin Naturwissenschaftlicher Sammlungen, ZNS) of the Martin Luther University Halle-Wittenberg

A new Upper Cretaceous (Cenomanian) dinosaur track locality El Chocón Medio from northwestern Patagonia, Argentina, is reported here. More than 30 true tracks (concave epireliefs) were recognized in fine-grained sandstone beds, interpreted as floodplain deposits. The only distinct trackway consist of six deep and medium-sized tridactyl tracks poorly preserved with distinct metatarsal impressions (about 50 cm long and 20 cm wide). This trackway does not reflect changes in footprint features such as track length, depth, pace and height of displacement rims, suggesting that the consistency of the substrate was homogenous along the complete distance. About 20 m from this trackway, several deeper and large tridactyl tracks (30 to 40 cm in length) with very pronounced rims have been identified. They are positioned close to each other and show different orientations, accordingly were considered as isolated tracks. They are poorly preserved and lack anatomical features, making it difficult to determine a theropod or ornithopod affinity. Finally, in the underlying bed (10 cm below) several subcircular (70 cm in diameter) and crescent-shaped (50 cm in width) natural cast tracks (pes-manus) of sauropods were documented. At least three sauropod pes from the same side (left or right) where arranged in an incomplete trackway, so the type of gauge could not be determined. Preliminarily, considering the similar morphology and heteropody, these tracks can be assigned to cf. Sauropodichnus giganteus Calvo, 1991, from the same unit and tracksite proximity. The present track assemblage shows that this site was repeatedly visited by different groups of dinosaurs.