Palaeoenvironmental implications of fossil termite traces in Late Pleistocene vertebrates from Northeastern Argentina

In South America, evidence of trace fossils on the bones of Pleistocene megafauna is scarce. Nevertheless, these trace fossils are significant to facilitate comprehension of associated palaeoen-vironmental, palaeoecological, and taphonomic conditions. They also provide data on the past interactions between insects and vertebrates. In this study, we describe trace fossils that we assign to Taotieichnus orientalis, representing the first occurrence of this ichnotaxon in Argentina and the third in South America. The trace fossils were found in remains of Pleistocene megafauna, including Hemiauchenia paradoxa (Artiodactyla), Neosclerocalyptus sp. (Glyptodontidae, Cingulata), and other indeterminate mammals. The specimens come from two units: the Río Bermejo Formation in Formosa Province (latest Pleistocene, MIS2; ca. 20 ka) and the Northern Salado River levels in Santa Fe Province (MIS3; ca 46.5 to 25.8 ka). Outcrops in both provinces correspond to fluvial environments, although each area represents a different climatic scenario, characterised by periods of sedimentary stability. This evidence extends the record of Taotieichnus orientalis, previously recorded from the Triassic to Quaternary sensu lato, with certainty, to the Late Pleistocene. The ichnofossils studied herein exhibit a strong morphological resemblance to subaerial foraging tunnels made by modern subterranean termites. This resemblance may be consistent with a specific, possibly seasonal, feeding behaviour in which decomposing vertebrate carcasses are used as an additional nutrient source through the construction of protective galleries. This study highlights the role of termites as trace-makers in bone and their taphonomic implications. Thus, these findings suggest that termites played a role in modifying and potentially destroying bone remains in past ecosystems in response to changes in nutrient availability. Furthermore, the presence of these trace fossils in fluvial settings of different ages establishes a consistent pattern of occurrence in these settings, demonstrating the plasticity of termite food sources over time.