DIETARY ECOLOGY OF THE LOCAL LANCEFIELD FAUNA IN VICTORIA, AUSTRALIA: DID THE KANGAROOS DIE FROM A MASSIVE DROUGHT?

The Lancefield swamp site in Victoria, Australia is thought to be a Pleistocene mass death assemblage of kangaroos, with approximately 1000 bones per square meter recovered across a 30m diameter area. The high fatality rate of kangaroos at this site has been thought to have resulted from either drought or predation. To date, little work has been done to assess the paleoecology of Lancefield kangaroos, which can be a powerful predictor in understanding causal factors relating to mass die offs. To this end, we carried out a dual-proxy approach using dental microwear textures and stable carbon isotopes to assess the dietary behavior of the macropodids found at the site, including the most abundant: Macropus giganteus titan. We compared the dental microwear textural attributes of anisotropy and complexity to extant Macropus giganteus specimens that died during normal years (i.e. culled specimens) or during drought events (i.e. pick-up skulls). Dental microwear, which is capable of recording an animal's most recent diet, suggests that the fossil specimens died during a massive drought (during which they consumed harder and less preferred woody browse), consistent with other geological and taphonomic evidence. Understanding the conditions during which these macropodids died is critical to understand the vulnerabilities of ancient and modern taxa, of relevance to today. Further, this provides additional evidence that "arid" adapted animals are still vulnerable to droughts and that drought as a major contributor of megafaunal extinctions cannot be ruled out.