How to measure a bite<\/h2>
Prior to the study, researchers at Flinders University already knew that some small species of rock-wallaby, such as the nabarlek, can eat similar types of food to relatives that are eight times larger.<\/p>
\u201cWe therefore suspected that something happened in the evolution of their jaws to allow them to stick to these diets,\u201d says\u00a0Vera Weisbecker, Flinders University Associate Professor in Evolutionary Biology, and co-author of the study.<\/p>
Intrigued to know more, the researchers scanned the skulls of nearly 400 rock-wallabies (all 17 species), which included two species of dwarf rock-wallaby. The extensive study allowed them to compare the different features that make up the skulls.<\/p>
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The results revealed that, aside from typical differences in brain and eye size that are usually seen between bigger and smaller animals, there were also differences in the features of the skull that are used for eating.<\/p>
Dr Mark Eldridge from the Australian Museum, who also co-authored the study, says: \u201cWe found clear indicators that both dwarf rock-wallabies have adaptations to harder biting: they had shorter, rounder snouts and teeth positioned at the back of the jaw where they are more effective at harder bites.\u201d<\/p>
![\"The](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/62\/2024\/03\/The-skull-of-a-pygmy-rock-wallaby-or-nabarlek.jpeg\")
The skull of a pygmy rock-wallaby or nabarlek (top) and a Proserpine rock-wallaby (bottom). While the brain and eyes are larger in the dwarf species, they also have larger cheekbones and teeth positioned further back in the jaw. These features increase the ability to bite harder. Credit: Dr R Mitchell, Flinders University<\/figcaption><\/figure> Mighty molars<\/h2>
The researchers also discovered some surprising differences in the size of the dwarf rock-wallaby teeth compared to the larger species; some of the teeth of the dwarfs were much larger, for their size, than those of the bigger species.<\/p>
\u201cThis makes sense, because many animals that need to bite harder into their foods tend to have bigger teeth for their size,\u201d says study leader\u00a0Dr Rex Mitchell from the\u00a0Morphological Evo-Devo Lab<\/a>\u00a0at Flinders University.<\/p>
Analysis of the skulls revealed that the nabarlek has the largest molars of all the rock-wallaby species. It is also the only species of marsupial known to continuously grow new molars throughout its life.<\/p>
While the nabarlek was observed as having the largest molars, the second dwarf species of rock-wallaby was found to have the largest premolars.<\/p>
This likely indicates adaptations to different vegetation types, say the scientists. Larger molars are better for grinding up grass and other plants that are closer to the ground, while larger premolars are better at slicing through the leaves and twigs of shrubs.<\/p>
\u201cIf I were a vegetable, I would not mess with a pygmy rock-wallaby,” says Dr Mitchell. “They totally have \u2018Little Wallaby Syndrome\u2019.\u201d<\/p>
“The findings are important because the functional effects of skull size on skull shape are often ignored because differences in size are not generally considered to be related to feeding adaptations,” adds Dr Mitchell.<\/p>
The research concludes that smaller animals often need to have harder-biting skulls than larger animals if they want to eat the same kinds of foods.<\/p>
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