Kangaroos kept a broad diet through late Pleistocene climate changes

Samuel Arman and colleagues’ close examination of tooth microwear among living and extinct kangaroo species suggests that most of the species living in Australia during the Late Pleistocene had a broad, generalist diet rather than being specialized grazers. This broad diet likely allowed them to survive the glacial-interglacial cycles that drove fluctuations in vegetation on the continent. The findings add more evidence to the idea that human hunting, rather than failure to adapt to climate changes, was behind the late megafaunal extinction in Australia. By 40,000 years ago, Australia had lost 90% of its large species, more than half of them kangaroos. To determine whether kangaroo species were able to adapt to climate-driven vegetation changes at the time, Arman et al. examined 2650 enamel scans from 937 individual specimens to characterize the diets of a diverse Pleistocene kangaroo fossil assemblage. Chewing food with different material properties leaves distinctive microscopic wear marks on tooth enamel that can then be associated with different diets. The researchers found no statistically significant differences in microwear among most species in the fossil assemblage, and the microwear itself suggested the species did not pursue specialized diets.