That Australian Megafauna Overkill Paper

Extinction implications of a chenopod browse diet for a giant Pleistocene kangaroo

1. Gavin J. Prideaux (a,1)
2. Linda K. Ayliffeb (c)
3. Larisa R. G. DeSantis (d)
4. Blaine W. Schubert (e)
5. Peter F. Murray (f)
6. Michael K. Gagan (c)
7. Thure E. Cerling (b)



a School of Biological Sciences, Flinders University, Bedford Park, South Australia 5042, Australia;

b Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112;

c Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia;

d Department of Biology, University of Florida, Gainesville, FL 32611;

e Department of Geosciences and Don Sundquist Center of Excellence in Paleontology, East Tennessee State University, Johnson City, TN 37614; and

f Museum of Central Australia, Alice Springs, Northern Territory 0871, Australia


Abstract:

Kangaroos are the world's most diverse group of herbivorous marsupials. Following late-Miocene intensification of aridity and seasonality, they radiated across Australia, becoming the continent's ecological equivalents of the artiodactyl ungulates elsewhere. Their diversity peaked during the Pleistocene, but by approximately 45,000 years ago, 90% of larger kangaroos were extinct, along with a range of other giant species. Resolving whether climate change or human arrival was the principal extinction cause remains highly contentious. Here we combine craniodental morphology, stable-isotopic, and dental microwear data to reveal that the largest-ever kangaroo, Procoptodon goliah, was a chenopod browse specialist, which may have had a preference for Atriplex (saltbushes), one of a few dicots using the C4 photosynthetic pathway. Furthermore, oxygen isotope signatures of P. goliah tooth enamel show that it drank more in low-rainfall areas than its grazing contemporaries, similar to modern saltbush feeders. Saltbushes and chenopod shrublands in general are poorly flammable, so landscape burning by humans is unlikely to have caused a reduction in fodder driving the species to extinction. Aridity is discounted as a primary cause because P. goliah evolved in response to increased aridity and disappeared during an interval wetter than many it survived earlier. Hunting by humans, who were also bound to water, may have been a more decisive factor in the extinction of this giant marsupial.

This is the paper that I linked about earlier.