Last updated September 12, 2019 at 5:41 pm
This ancient kangaroo had a skull that was less like a modern kangaroo and more like a panda.
Why This Matters: Cute but giant kangaroo that packs a powerful bite? Ancient Australia was a place of nightmares.
Turns out that Australia’s ancient kangaroo species have more in common with giant pandas that modern macropods.
Still hopping until about 42,000 years ago, S. occidentalis, sometimes called “short-faced” kangaroo may have looked cute, but packed a ferocious bite from its heavily built skull, and large jaws and teeth.
Weighing in at a hefty 118 kilograms, the ancient kangaroo would have dominated today’s red kangaroo, which is the largest current living macropod but tops out at a relatively titchy 90 kilograms.
But while it sounds impressive, S. occidentalis barely matches up against the largest macropod to have ever lived – Procoptodon goliah. A two-metre-tall, 200-kilogram-plus bruiser, P. goliah most likely disappeared about 50,000 years ago, which makes it likely the two huge macropods lived at the same time.
Powerful jaws for a diet of tough foods
Past research of their skull features suggested that these animals had powerful jaws adapted for a diet of tough foods such as mature leaves, stems, and branches.
Mitchell hypothesised that if this is true, the kangaroos’ skulls should also be built to resist the forces that such powerful bites would put on skull bones and joints.
He created a digital model of a S. occidentalis skull, ran a series of bite simulations, then compared them to the bite of a koala – the extant animal considered to have the most similar ecology and skull type.
Differences between the two include the positioning of S. occidentalis’s cheek teeth. They extend further back on the jaw bones than do a koala’s and would thus have put much more force on the jaw joint and increased the likelihood of jaw dislocation.
The simulations revealed that S. occidentalis could produce and withstand comparatively heavy forces when biting unilaterally – specifically, when feeding very tough materials into the cheek teeth on one side of its mouth, much as a giant panda does with a bamboo stem.
Skulls to withstand its powerful bite
S. occidentalis’s cheekbones, Mitchell found, supported large muscles that would prevent its jaw from being dislocated during strong biting, and that the bones of the front and roof of the skull formed an arch that would resist twisting forces during bites.
These attributes support the suggestion that these kangaroos’ skulls were well adapted to producing and withstanding powerful bite forces, which would have allowed them to eat tough, low-nutrition foods that may have been inaccessible to other species.
Mitchell notes that the ancient kangaroo appears adapted to exploit tough foods to a greater extent than any living Australian herbivore, meaning these kangaroos represent a feeding behaviour and ecology that’s no longer seen on the continent.
“The skull of the extinct kangaroo studied here differs from those of today’s kangaroos in many of the ways a giant panda’s skull differs from other bears,” says Mitchell.
“So, it seems that the strange skull of this kangaroo was, in a functional sense, less like a modern-day kangaroo’s and more like a giant panda’s.”
The full study is published in the journal PLOS ONE.