Paleobiology of avian and mammalian fossil footprints from the south of South America. Expositor

KRAPOVICKAS, V.; MARSICANO, C.A.; MÀNGANO, M.G.

Bristol, Inglaterra

Congreso; SVP 69th Annual Meeting; 2009

University of Bristol

Three consecutive tetrapod fossil footprint assemblages were recorded from non-marine sediments of the Vinchina broken-foreland basin, La Rioja Province, Argentina. The footprint assemblages are preserved at the Vinchina (Oligocene to Early Miocene) and Toro Negro (Miocene to Early Pliocene) formations. The oldest assemblage (I) occurs in the Vinchina Formation at Quebrada de La Troya. Assemblage II corresponds to the specimens recorded by Bonaparte in the 60’s near the top of the Vinchina Formation at Quebrada del Yeso. The youngest assemblage (III) was recently documented in the Lower Member of the Toro Negro Formation at Quebrada de La Troya. These assemblages present both similarities and differences. All three contain footprints related to the activity of large cursorial birds, such as Rheiformes and phororhacids, as well as those of macraucheniids. Furthermore, assemblages II and III share certain features amongst themselves, such as footprints produced most-likely by shorebirds and others by large tardigrads.  By contrast, assemblage I records several distinct footprints (i.e. Gruipeda isp., small tridactyl rodent-like footprints and large tetradactyl rodent-like footprints).  In like manner, assemblage II records footprints most-likely produced by Ralliformes. Assemblage III is the most diverse, suggesting the presence of perching birds, medium heteropod rodent-like mammals, medium-small tardigrads and proterotheriids, besides those previously mentioned. As a result, the paleobiological interpretation of these fossil footprint associations complement our knowledge of NW Argentina ancient faunas based on body fossils, and document the evolution of the local tetrapod fauna.