Paleontologists have redescribed Zygomaturus keanei, a species of marsupial that lived in Australia some 3.5 million years ago (Pliocene period), using new skeletal remains from northern South Australia and placed this quarter-ton animal in a new genus, Ambulator; the locomotory adaptations of the animal’s legs and feet would have made it well suited to roam long distances in search of food and water when compared to earlier relatives.
Diprotodontids are members of Diprotodontidae, an extinct family of large herbivorous marsupials.
These animals were endemic to Australia and New Guinea during the Oligocene through Pleistocene periods from 28.4 million to 40,000 years ago.
They likely had to travel much greater distances to obtain enough food and water to keep them going.
The largest species, Diprotodon optatum, grew to the size of a car, weighing up to 2.7 tons.
“Diprotodontids are distantly related to wombats — the same distance as kangaroos are to possums — so unfortunately there is nothing quite like them today,” said Flinders University Ph.D. candidate Jacob van Zoelen.
“As a result, paleontologists have had a hard time reconstructing their biology.”
During the Pliocene period, when Ambulator keanei was alive, there was an increase in grasslands and open habitat as Australia became drier.
“We don’t often think of walking as a special skill but when you’re big any movement can be energetically costly so efficiency is key,” van Zoelen said.
“Most large herbivores today such as elephants and rhinoceroses are digitigrade, meaning they walk on the tips of their toes with their heel not touching the ground.”
Using 3D-scanning technology van Zoelen and colleagues were able to compare the partial skeleton with other diprotodontid material from collections all over the world.
By CT scanning the specimen, soft tissue impressions preserving the outline of the footpad were revealed.
“Diprotodontids are what we call plantigrade, meaning…
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