Could extinct giant short-faced kangaroos hop?

Extinct giant short-faced kangaroo. Credit: Arthur Weasley

Simosterunus occidental was one of the largest-known kangaroos to ever existed. It is a species of giant short-faced kangaroo, distinguishable by their flat faces and forward-pointing eyes. The genus went extinct approximately 50 000 years ago, although there is some evidence they may have survived to as recently as 18 000 years ago. Its extinction may have been due to human hunting or climate change during the Pleistocene.

Simosterunus occidental weighed up to 180 kg – about the size of a modern grey kangaroo – but was more robust. Whether this species was able to hop like extant kangaroos has been a highly controverial topic, with some arguing that this species was limited to slower forms of locomotion. As their capability to hop is debatable, we provide a biomechanical approach to the topic.

Reconstruction of the largest extinct kangaroo, Procroptodon goliah. Credit: Monsieur X

Using finite element analysis, we mapped estimated stress caused by ground reaction force for thirteen extant macropodoid species and one S. occidentalis across a range of duty factors observed in hopping macropods (a ratio of time of contact/time of stride). Results indicate clear discrepancies between stress distribution between large extant kangaroos and S. occidentalis. Further details will be made available upon publication.

IN PREPARATION

Cook JD, Attard MRG, Evans S, Goatly C, Clausen P and Wroe S. (In Prep) The bigger they are, the harder they hop? Using finite element modelling to map stress distribution in the femur of S. occidentalis compared to extant macropodoids.

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