Well-drained floodplain taphonomic mode of Late Pleistocene vertebrates from Northeast Argentina

Abstract

The vertebrate assemblage recovered from the Toropí/Yupoí Formation (Late Pleistocene) in the Arroyo Toropí area, Bella Vista (Corrientes Province, Argentina), has been subjected to taphonomic evaluation. The fossil-bearing levels have been dated to ~53 ka (MIS 3) based on Optically Stimulated Luminescence dating. This assemblage primarily comprises mammal remains, with a notable prevalence of herbivorous megamammals. Also, reptiles and birds have been documented. Sedimentological analysis suggests that the skeletal remains were preserved within a floodplain environment influenced by the dynamics of the adjacent fluvial system, and taphonomic features observed in the assemblage support this interpretation. The assemblage resulted from the deposition of disarticulated mammal remains and local dispersion over a relatively short period. Rapid burial is evident, but several processes such as weathering and breakage have contributed to the observed patterns. The loss of several skeletal elements within the assemblage may be attributed to sporadic water flows occurring on the floodplain. During the post-burial stage, the specimens were affected by diagenetic processes, including filling, impregnation, deformation and breakage. In summary, the taphonomic evaluation of the Toropí/Yupoí Formation offers valuable comparison with other fossil fluvial assemblages. This research contributes to our understanding of the processes and environmental conditions that shaped this Late Pleistocene ecosystem.