Ecomorphological determinations in the absence of living analogs: the predatory behavior of the marsupial lion (Thylacoleo carnifex) as revealed by elbow-joint morphology

Thylacoleo carnifex, or the \"pouched lion\" (Mammalia: Marsupialia: Diprotodontia: Thylacoleonidae) was a carnivorous marsupial that inhabited Australia during the Pleistocene. Although today all authors agree that Thylacoleo had a hypercarnivorous diet, the way in which it killed its prey remains uncertain. Here we use geometric morphometrics to capture the shape of the elbow joint (i.e., the posterior articular surface of the distal humerus) in a wide sample of extant mammals of known behavior to determine how elbow anatomy reflects forearm use. We then employ this information to investigate the predatory behavior of Thylacoleo. A Principal Components Analysis indicates that Thylacoleo is the only carnivorous mammal to cluster with extant taxa that have an extreme degree of forearm maneuverability, such as primates and arboreal xenarthrans (pilosans). A Canonical Variates Analysis confirms that Thylacoleo had forearm maneuverability intermediate between wombats (terrestrial) and arbore...