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

Abstract

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 Nimbadon lavarackorum, based on its post-cranial morphology, is thought to have occupied the treetops. Understanding the dietary ecology of N. lavarackorum 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 N. lavarackorum 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 N. lavarackorum (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 N. lavarackorum 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 ca 70 kg marsupial moving into or staying in the treetops—an ecological niche that is currently unoccupied in Australia today.

Larisa DeSantis [[email protected]], Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN 37240, USA; Michael Archer [[email protected]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia; Karen Black [[email protected]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia; Suzanne Hand [[email protected]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia; Vera Korasidis [[email protected]], Department of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, VIC, 3010, Australia.

Keywords:

• Cenozoic
• dental microwear
• diet
• mammal
• palaeoecology
• Riversleigh
• stable isotopes

Acknowledgements

We would like to thank all museum staff, curators, and collection managers who assisted with access to this material at the American Museum of Natural History and Queensland Museum. We are thankful to J. Curtis (University of Florida) for isotopic analysis, E. Mueller for assistance with Fig. 3. We are beholden to the Waanyi Aboriginal Community of northwestern Queensland and, for their ongoing support, we thank Queensland Parks and Wildlife Service, Environment Australia, Outback at Isa, Mount Isa City Council, Phil Creaser and the CREATE fund at UNSW, and the Rackham family. We are also grateful to the many students and volunteers for their support and assistance in the research at Riversleigh World Heritage Site.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Funding was provided by the National Science Foundation (1455198), Australian Research Council [DE130100467, DP170101420], Vanderbilt University, and the University of New South Wales.