Vertebrate tracks of the Río Negro province, Patagonia, Argentina: stratigraphy, palaeobiology and environmental contexts

Abstract

To date, the tetrapod ichnological record in the Río Negro province, Argentina, is known from six areas from the Permo-Triassicto Neogene. Tetrapod tracks have been identified in different palaeoenvironments and geodinamic contexts. The oldest track record is represented by the therapsid tracks from the Los Menucos Group. A prevailing Dicynodontipus and Dicynodontipus-like footprints, Lopingian-Early Triassic in age, comes from the Tscherig and Puesto Vera localities, while Pentasauropus tracks, presumably Late Triassic in age,were recognized in the Yancaqueo locality. A tridactyl track-bearing level, still unpublished (related to El Refugio Formation, Middle-Upper Triassic), has been found in the Puesto Prado farm, in the Arroyo de la Ventana area. Some tracks classified as cf. Anomoepus and undetermined tridactyl tracks have been identified in the Perdomo farm(Marifil Volcanic Complex). The Late Cretaceous (Cenomanian) record is represented by the ornithopod, sauropod and theropod tracks from the Candeleros Formation (Ezequiel Ramos Mexía area). Moreover, cf. Iguanodontipodidae, sauropod and avian tracks from the Anacleto and Allen Formations characterise the latest Cretaceous (Campanian-early Maastrichtian) of the Paso Córdoba area.Avian tracks were also reportedfromthe Ingeniero Jacobacci area, from the Angostura Colorada Formation (upper Campanian-lower Maastrichtian), andfrom the Río Negro Formation (upper Miocene-lower Pliocene) along the shoreline of the province. In this area, tens of tracksites and several ichnotaxa have been studied. In regard of palaeoenvironments, ichnosites are constrained to three main sedimentary settings: fluviovolcaniclastic, fluvial/fluvial-aeolian and shallow marine systems. Finally, a brief discussion about palaeobiology and heritage issues is provided.