A comparative study of the postcranial skeleton of Patagonian and Pampean specimens of the Pleistocene giant sloth genus Mylodon Owen, 1839 (Xenarthra, Pilosa) and its implications

In this work, we describe postcranial elements of Mylodon listai distributed in collections from Argentina, Chile and Europe. Mylodon listai remains from Patagonia are clearly different from those from the Pampean region (Mylodon darwinii), presenting morphological differences in their postcranium such as a smaller intercondylar space and less displacement of the medial condyle in the femur. These anatomical features reveal that M. listai had less bowed legs than M. darwinii. We propose that this would be an adaptation to a less fossorial lifestyle in their habitats in southern Patagonia without having to do directly with differences in body mass in the southern specimens, because M. listai would have reached similar or even larger sizes than M. darwinii.