Tree-climbing in search of fruit: an ancient arboreal marsupial megafrugivore from the Miocene of Australia

Diprotodontids, a group of large-bodied wombat-like marsupial herbivores, were broadly distributed in Australasian Cenozoic deposits. While most diprotodontids were terrestrial quadrupeds and are often compared to placental herbivores like rhinoceros and hippopotamuses, the zygomaturine diprotodontid <i>Nimbadon lavarackorum</i>, based on its post-cranial morphology, is thought to have occupied the treetops. Understanding the dietary ecology of <i>N. lavarackorum</i> during the Miocene can help clarify potential motivations for an arboreal lifestyle. Here, we conducted dental microwear texture analysis (DMTA) and stable isotope analysis (SIA) of <i>N. lavarackorum</i> specimens from the Riversleigh World Heritage Area and compared them to analogous extant mammals to assess the likelihood that these tree-dwelling marsupials occupied a unique ecological niche during the Miocene in Australia—arboreal megafrugivores. The DMTA of <i>N. lavarackorum</i> (i.e., low anisotropy and high complexity) is most similar to extant mammals that include a high proportion of fruit in their diet and is inconsistent with and statistically distinct from obligate folivores. Stable carbon isotopes of <i>N. lavarackorum</i> also indicate the consumption of C₃ food sources, consistent with the consumption of ¹³C enriched fruit in a C₃ forest environment. Fruits may have been a motivation for this <i>ca</i> 70 kg marsupial moving into or staying in the treetops—an ecological niche that is currently unoccupied in Australia today. <i>Larisa DeSantis [[e-mail]], Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN 37240, USA; Michael Archer [[e-mail]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia; Karen Black [[e-mail]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia; Suzanne Hand [[e-mail]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia; Vera Korasidis [[e-mail]], Department of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, VIC, 3010, Australia.</i>