José Luis Lanata

Direct evidence of megamammal-carnivore interaction decoded from bone marks in historical fossil collections from the Pampean region

Pleistocene South American megafauna has traditionally attracted the interest of scientists and the popular media alike. However, ecological interactions between the species that inhabited these ecosystems, such as predator-prey relationships or interspecific competition, are poorly known. To this regard, carnivore marks imprinted on the fossil bones of megamammal remains are very useful for deciphering biological activity and, hence, potential interspecific relationships among taxa. In this article, we study historical fossil collections housed in different European and Argentinean museums that were excavated during the 19th and early 20th centuries in the Pampean region, Argentina, in order to detect carnivore marks on bones of megamammals and provide crucial information on the ecological relationships between South American taxa during the Pleistocene. Our results indicate that the long bones of megafauna from the Pampean region (e.g., the Mylodontidae and Toxodontidae families) exhibit carnivore marks. Furthermore, long bones of medium-sized species and indeterminate bones also present punctures, pits, scores and fractures. Members of the large-carnivore guild, such as ursids, canids and even felids, are recognised as the main agents that inflicted the marks. We hypothesize that the analysed carnivore marks represent the last stages of megaherbivore carcass exploitation, suggesting full consumption of these animals by the same or multiple taxa in a hunting and/or scavenging scenario. Moreover, our observations provide novel insights that help further our understanding of the palaeoecological relationships of these unique communities of megamammals.

DESCRIPTION AND INTERPRETATION OF A MEGATHERIUM AMERICANUM ATLAS WITH EVIDENCE OF HUMAN INTERVENTION

This paper discusses a Megatherium americanum atlas from the Pampas region of Argentina, which is currently housed at the Museo di Storia Naturale di Firenze, Italy. Traces of anthropic cut marks were found on the dorsal and ventral faces of the posterior part, in articulation with the axis. This is the first time that this type of evidence has been documented on this element of this species. The position of these marks suggests that they resulted from the act of separating the head from the postcranial skeleton. They were therefore most likely made in an effort to exploit the contents of the head. Current research focusing on museum collections employing modern methods can provide new and valuable information, despite the general lack of contextualization of these pieces. In the case studied here, these methods have allowed us to delve deeper into the first dispersal of Homo sapiens and their interaction with the native fauna in the South American Southern Cone.