Iconic Swartkrans fossils and hominid taxonomy, II: SK 54 calotte

The juvenile hominid calotte, SK 54, from Swartkrans Member 1, is well-known for its taphonomic circumstances, having been punctured by the canine teeth of a carnivore. This finding by C.K. Brain was the most dramatic observation he brought to bear in support of his ‘leopard hypothesis,’ which proposed that many Paranthropus robustus individuals whose fossils are represented at Swartkrans came to rest there as the victims of predators. Correspondingly, it is often supposed that coeval early Homo was more intelligent than P. robustus and, in turn, also more elusive, mostly avoiding a similar fate. The authors of a recent paper stress that their taxonomic re-assignment of SK 54 from P. robustus to the genus Homo weakens “the historically significant hypothesis that Homo was better able to avoid predation because of being behaviourally and technologically advanced compared to Paranthropus” (Martin et al., 2024: 1). Here, we critically assess Martin et al.’s (2024), as well as Braga et al.’s (2023), claim that SK 54 should be re-assigned to the genus Homo. In doing so, we also emphasise salient morphological and taphonomic data that indicate, collectively, the fossil should be, instead, retained in P. robustus.