New study reveals giant size of extinct marsupials that once roamed Australia
A handout illustration made by Hazel Richards of Australia's Monash University shows the comparative size of Palorchestes azael – an extinct species of giant marsupial that once lived in Australia – next to a wombat and a human female, released on Sept. 13, 2019. EFE-EPA HANDOUT/HAZEL RICHARDS/MONASH UNIVERSITY
Washington, Sep 13 (efe-epa).- Paleontologists have found that a species belonging to an extinct genus of marsupial that roamed Australia some 25 million ago had a gigantic size and could reach a weight of more than 1,000 kilograms (2,200 pounds).
The study, which was carried out by scientists at Australia's Monash University, was published in the open-access scientific journal PLOS ONE on Friday.
The researchers studied some 60 samples of fossilized bones belonging to the Palorchestidae ("ancient leaper") family of giant diprotodontid marsupials.
Although the existence of palorchestids has been known for many decades, the Australian scientists managed to form the first formal descriptions of their appendicular morphology and reach conclusions about their huge size.
"Results indicate palorchestids were bigger than previously thought, with the largest species likely weighing over 1,000 kg," the article said.
These giant quadrupeds possessed a suite of morphological features totally unlike any living mammal, including a skull with hyper-retracted nasals and extremely muscular specialized forelimbs equipped with enormous scimitar-like claws, an evolutionary adaptation that likely served to allow the herbivore creatures to grab or scrape at leaves and branches.
"The shape of the humeroulnar articulation in P. azael would have effectively fixed the elbow in a flexed posture approaching a 100-degree angle," the study found. "This elbow appears to be a palorchestid adaptation for a particularly specialized use of the forelimb, likely in acquiring food."
"This study has allowed us for the first time to appreciate just how huge these mega-marsupial palorchestids were, while also providing the first comprehensive view of a strange limb anatomy unprecedented in the mammalian world," the authors said in a statement.
"This research reveals yet more about the diversity of unique large marsupials that once roamed Australia not so long ago," the research team, led by Hazel Richards, added.
The palorchestids lived between the Late Oligocene (25-23 million years ago) and Late Pleistocene (126,000-12,000 years ago) epochs.
Australia’s marsupial megafauna became largely extinct during the Late Pleistocene, likely due to a combination of climatic change and human activity.
Marsupials are an infraclass of mammals that carry their young in characteristic pouches and are mainly found in Australasia – though there are also some endemic to South America – and presently include species such as koalas, kangaroos, wombats, wallabies, Tasmanian devils, opossums, protoroos and cuscuses. EFE-EPA