Cute little marsupials pack a punch at mealtimes

(Press-News.org) Native Australian animals range from high-hopping kangaroos to fast-running emus – but clever little bettongs also have a special ability to find and eat the food they love.  

Flinders University researchers have discovered the secrets behind a superpower of these tiny relatives of kangaroos which allows them to crack open seeds that would break the jaws of most animals. They hope the research will help conservation efforts, including finding suitable locations to reintroduce populations severely impacted by predation and habitat loss.  

The new study, published in the Zoological Journal of the Linnean Society, reveals how two species of these threatened bettongs possess different adaptations to enjoy one particularly tough favourite food of theirs – Santalum seeds, which include the sandalwood, and Australia’s native peach (or quandong).

First author Maddison Randall, Flinders University PhD candidate, says the rabbit-sized marsupials are essential to their environments, spending most of their time digging in search of soft foods such as underground fungi, roots and tubers.

While most bettongs typically feed on softer foods, the burrowing bettong (Bettongia lesueur or ‘boodie’) and the brush-tailed bettong (Bettongia penicillata or ‘woylie’), are also known to crack open the tough outer shells of sandalwood and quandong seeds to obtain the nutritious kernels from inside.

“These seeds are extraordinarily tough, needing bite forces much higher than typical rabbit-sized animals can produce to crack them open,” says Ms Randall, from the College of Science and Engineering.

“We expected the skulls of these tiny animals to have jaw adaptations that can handle higher bite forces but were surprised to find that the two seed-cracking species have developed different biting adaptations to solve the same tough-shelled challenge.”

The team scanned 161 bettong skulls from museums across Australia, including all four living species in the genus, with the eastern bettong (Bettongia gaimardi) and the northern bettong (Bettongia tropica). Using these digital reconstructions of the skull scans, they were able to compare skull shape across the genus using 3D shape analysis.

Flinders University Professor Vera Weisbecker, who co-authored the study, says the jaw adaptations of the two closely related species were not as similar as expected.

“The boodie has a shorter face than the other species. This gives it more leverage, allowing harder biting. But the woylie doesn’t have a shorter face. It instead has a reinforced part of the skull where biting the seeds takes place,” she says.

Another co-author Dr Rex Mitchell adds the difference in snout length may be because the woylie, unlike the boodie, also relies much more on underground fungi (truffles). Thus, their longer snout might help them sniff these out by providing more surface area inside their noses for their sense of smell.

“Understanding animal dietary needs and their associated adaptations is invaluable information for conservation of threatened species,” says Dr Mitchell.

“All four species of bettong around today are threatened to some degree and have been reduced to a fraction of their range since European settlement.

“Therefore, information about their dietary needs, limits and capabilities is vital for conservation and could be used to inform suitable habitat for reintroduction initiatives.”

Bettongs’ other superpower is their major role as ecosystem engineers, with their digging and foraging behaviour turning over soils and leaf litter which improves soils health, water filtration, seed germination and, ultimately, helps ecosystems thrive.

Despite their struggling numbers, these tiny but mighty marsupials are a powerful reminder that there's more than one way to crack a tough nut.

The article, ‘Cracking the case: Differential adaptations to hard biting dominate cranial shape in rat-kangaroos (Potoroidae: Bettongia) with divergent diets (2025) by Maddison C Randall, Vera Weisbecker, Meg Martin, Kenny J Travouillon (WA Museum), Jake Newman-Martin (Curtin University, WA) and D Rex Mitchell has been published in Zoological Journal of the Linnean Society, DOI: 10.1093/zoolinnean/zlaf158.  https://doi.org/10.1093/zoolinnean/zlaf158

Acknowledgements: This research received funding from the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CE170100015), and a Future Fellowship (FT180100634) to Professor Weisbecker. This research was conducted on the unceded lands of the Kaurna people.

Thanks to all the Australian museums for access to scan their specimens and for assistance from the ANFF under the National Collaborative Research Infrastructure Strategy and Flinders Microscopy and Microanalysis.

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