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Two Different ‘Nut-Cracking’ Evolutions: How Bettongs Bite Through Hard Seeds

Researchers scanned 161 museum skulls of the four living bettong species to investigate how these rabbit-sized Australian marsupials crack very hard seeds. The burrowing bettong (B. lesueur) uses a shortened, robust snout to amplify bite force, while the brush-tailed bettong (B. penicillata) relies on reinforced, chisel-like premolars and a longer face that may house large nasal passages for truffle scenting. Rather than converging on one solution, the two seed-eaters evolved different anatomical specializations independently—findings that have implications for functional ecology and conservation.

06:28 AM, 11/27/2025Science
Two Different ‘Nut-Cracking’ Evolutions: How Bettongs Bite Through Hard Seeds

Australia’s small nocturnal marsupials known as bettongs (Bettongia) face a tough culinary challenge: the extremely hard-shelled seeds of trees such as sandalwood and quandong. A new study in the Zoological Journal of the Linnean Society used three-dimensional scans to compare the skulls and jaws of the four living bettong species and reveal two distinct anatomical solutions for cracking those seeds.

Study approach. Researchers scanned 161 museum skulls and performed a 3-D shape analysis to test whether species that eat hard seeds had evolved similar cranial adaptations. Because diet often shapes the form of skulls, jaws and teeth, the team expected the two seed-cracking species to converge on a common mechanical design.

Two species, two solutions. The burrowing bettong, B. lesueur (the ‘‘boodie’’), has a notably shorter, more compact face. This shortened snout provides a mechanical advantage: jaw muscles can generate greater bite force over a shorter distance, helping the boodie break open tough seed shells.

By contrast, the brush-tailed bettong, B. penicillata (the ‘‘woylie’’), retains a relatively longer face but shows reinforced dental and jaw structures. Its premolars are more chisel-like and positioned to resist high stresses during seed cracking. The longer snout may also accommodate enlarged nasal passages used to scent out truffles, an important food source for the woylie.

“Understanding animal dietary needs and their associated adaptations is invaluable information for conservation of threatened species,” said Rex Mitchell, a comparative anatomist and co-author of the study.

Implications. Rather than converging on a single cranial design, the boodie and woylie evolved independent anatomical strategies to solve the same biomechanical problem. This demonstrates that closely related species can adopt different mechanical solutions to similar ecological challenges—insights that inform functional ecology and conservation planning for threatened marsupials.

Takeaway. The study shows there is more than one evolutionary way to crack a hard nut: one species favors brute-force mechanics, the other relies on specialized teeth and reinforced jaws.

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