> Thylacine crania are far larger than expected for their body mass, as determined by their centroid size (Fig. 3a), and exceed the absolute cranial sizes of far larger marsupials such as red kangaroos (Supplementary Fig. 5). While the thylacine weighs ~17 kgs34, its cranial size (within ±10%) is similar to that of much larger species, between 24.5 and 66.7 kg (Fig. 3a). In contrast, most placental carnivorans that are close to the thylacine in overall cranial shape (Figs. 1b and 2a) are jackals and foxes weighing 6–14 kgs (Fig. 3b). The cranial size of the thylacine is on par with much heavier predators such as the grey wolf, African wild dog (Lycaon pictus), puma (Puma concolor), and leopard (Panthera pardus).
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> The large size of the thylacine cranium has not been integrated into interpretations of its function, possibly because morphometric analyses generally remove absolute size43,44 and biomechanical comparisons usually focus on comparative, rather than absolute, generation of bite force44. However, a large cranium counteracts the weaker structure of a long and narrow rostrum by increasing the absolute magnitude of rostral resilience to stress and bite force. This is because larger crania are more resilient to intrinsic and extrinsic loads3,44 and carry more muscle3 compared to smaller crania that share the same shape. It is also possible that the wide zygomatic arch compared to other canids, particularly in larger thylacines (Fig. 4e), plays a role in buttressing the jaw joint against the leverage of the long jaw3,45, but this remains to be tested. Overall, the large size of the thylacine cranium thus indicates a specific mechanism of prey capture and/or immobilisation optimised for fast, high-impact bites whose force was dissipated across a large volume of cranial bone.
speerer•10m ago
> Thylacine crania are far larger than expected for their body mass, as determined by their centroid size (Fig. 3a), and exceed the absolute cranial sizes of far larger marsupials such as red kangaroos (Supplementary Fig. 5). While the thylacine weighs ~17 kgs34, its cranial size (within ±10%) is similar to that of much larger species, between 24.5 and 66.7 kg (Fig. 3a). In contrast, most placental carnivorans that are close to the thylacine in overall cranial shape (Figs. 1b and 2a) are jackals and foxes weighing 6–14 kgs (Fig. 3b). The cranial size of the thylacine is on par with much heavier predators such as the grey wolf, African wild dog (Lycaon pictus), puma (Puma concolor), and leopard (Panthera pardus).
...
> The large size of the thylacine cranium has not been integrated into interpretations of its function, possibly because morphometric analyses generally remove absolute size43,44 and biomechanical comparisons usually focus on comparative, rather than absolute, generation of bite force44. However, a large cranium counteracts the weaker structure of a long and narrow rostrum by increasing the absolute magnitude of rostral resilience to stress and bite force. This is because larger crania are more resilient to intrinsic and extrinsic loads3,44 and carry more muscle3 compared to smaller crania that share the same shape. It is also possible that the wide zygomatic arch compared to other canids, particularly in larger thylacines (Fig. 4e), plays a role in buttressing the jaw joint against the leverage of the long jaw3,45, but this remains to be tested. Overall, the large size of the thylacine cranium thus indicates a specific mechanism of prey capture and/or immobilisation optimised for fast, high-impact bites whose force was dissipated across a large volume of cranial bone.