Identifying remains of extinct kangaroos in Late Pleistocene deposits using collagen fingerprinting

Our knowledge of past animal populations, including the geographical ranges of extinct species, has largely been derived from morphological analyses of skeletal fossil remains. However, a major barrier to the identification of the remains of extinct megafaunal species in archaeological and palaeontological sites is the highly fragmented nature of the material, which often precludes confident taxonomic identifications based on morphology. Biomolecular techniques are able to go beyond these limitations and are increasingly being used to make such identifications. Protein analysis offers a promising alternative to DNA techniques because they can be much cheaper, more amenable to high-throughput processing and work on much older specimens. Here we demonstrate the potential of collagen fingerprinting in an Australian context by extracting collagen from 50-ka kangaroo fossils from two caves in Tasmania, and identify several species including the extinct short-faced kangaroo Simosthenurus occidentalis. Importantly, of the five fossil bones sampled that had hitherto been ascribed morphology-based identifications below the family level, three had been incorrectly identified during an initial assessment of photographs taken in the field. Our results highlight the utility of using protein-based methods for making genus-level identification of marsupial bone, especially those that may form a basis for broader arguments such as that of late-surviving megafaunal species.