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Research Associate in Palaeontology
Sam Arman

My focus is studying dental microwear of kangaroos. When an animal chews its food, it leaves microscopic scratches on the teeth. These scratches are called dental microwear. The shape of these scratches changes depending on the sorts of foods the animal is eating. For example, grasses tend to leave many thin scratches, but eating leaves and twigs of shrubs leaves deep and wide scratches.

The way dental microwear research takes place is to take a tooth and scan it under a confocal profiler – a high-resolution microscope which creates a 3D surface, digitally replicating a tiny section of the tooth surface. We then run algorithms across this surface that define its physical properties and allow us a way to mathematically compare different surfaces.

My main focus is using microwear to better understand the ecology of Pleistocene kangaroos. This was a time when we saw the greatest diversity in kangaroos, but also the dramatic ‘megafaunal extinctions’ which saw the loss of many species, including all of the Sthenurine or ‘short-faced’ kangaroos. What comprised the diets of Sthenurine kangaroos is one question I want to answer, and also whether this diet might have played a role in their extinction. More broadly though I am trying to tie together the diets of all kangaroos from one fossil deposit to better understand how they partitioned dietary resources amongst different species.

Another project I am working on is taking a much longer overview of kangaroo dietary evolution. Kangaroos evolved from a possum-like ancestor around 30 million years ago, at a time when there were no grasslands in Australia. Today, kangaroos dominate, especially in grassy regions. When and how this occurred is still being determined, with dental microwear being used as one of a number of proxies to understand this important shift in Australian climates.