Researchers Break Remains Of Bizarre Grouping Of Extinct Snail-Eating Marsupials

Fossil remains of a previously unknown menage unit of measurement of carnivorous Australian marsupials that lived fifteen meg years agone bring been discovered at the Riversleigh World Heritage Fossil Site inwards north-western Queensland yesteryear a UNSW Australia-led squad of researchers.

An artist's example of fifteen million-year-old Malleodectes from Riversleigh, chomping downward on what 
appears to bring been its favourite food—snails. The massive, shell-cracking premolar tooth
 is visible inwards the opened upward oral fissure [Credit: Peter Schouten]

"Malleodectes mirabilis was a bizarre mammal, equally foreign inwards its ain agency equally a koala or kangaroo," says report Pb writer UNSW Professor Mike Archer.

"Uniquely amid mammals, it appears to bring had an insatiable appetite for escargot--snails inwards the whole shell. Its most hitting characteristic was a huge, extremely powerful, hammer-like premolar that would bring been able to crevice in addition to and then shell the strongest snail shells inwards the forest."

Isolated teeth in addition to partial dentitions of this odd group, known equally malleodectids, had been unearthed over the years at Riversleigh, where Professor Archer in addition to his colleagues bring excavated for almost 4 decades. But the profoundly unlike nature of the marsupials was non realised until a well-preserved part of the skull of a juvenile was constitute inwards a fifteen meg twelvemonth sometime Middle Miocene cave deposit at Riversleigh.

This juvenile specimen was solely lately extracted from its limestone casing, using an acid bathroom at UNSW, which made it available for report alongside modern techniques including micro-computed tomography. The immature brute yet had its babe teeth, in addition to was teething, alongside adult teeth that had been close to erupt when it was move yet embedded inwards its jaw.

"Details of the canine, premolar in addition to tooth teeth of this specimen bring enabled its relationships to other Australian marsupials to move determined alongside reasonable confidence," says Professor Archer, of the PANGEA Research Centre inwards the UNSW School of Biological, public in addition to Environmental Sciences.

"Although it is real unlike from the others, it appears to bring been related to the dasyures -- marsupial carnivores such equally Tasmanian Devils in addition to the extinct Tasmanian Tigers that are unique to Commonwealth of Australia in addition to New Guinea."

Nothing remains of the cave at Riversleigh, known equally AL90 site, except its limestone floor, which contains the bones of thousands of animals that barbarous into, or lived in, the ancient cave.

"The juvenile malleodectid could bring been clinging to the dorsum of its woman rear piece she was hunting for snails inwards the rocks roughly the cave's entrance, in addition to may bring fallen inwards in addition to and then been unable to climb dorsum out," says squad fellow member UNSW Professor Suzanne Hand.

These are maxilla of the immature malleodectid - a snail-eating marsupial - constitute inwards the fossil cave deposit
 at Riversleigh. Because this is a juvenile, the massive premolar is yet unerupted below the tooth row 
[Credit: Karen Black in addition to Suzanne Hand/UNSW]

"Many other animals that lived inwards this lush wood met a similar fate alongside their skeletons accumulating i on run yesteryear of some other for maybe thousands of years, until the cave became filled alongside palaeontological treasures.

"Over millions of years the walls in addition to ceiling of the cave were eroded away, leaving solely the fossil-rich floor, which was discovered yesteryear our Riversleigh Project squad members inwards 1990."

Subsequent quarrying of the cave flooring has produced thousands of exquisite fossils including the articulated skeletons of the ram-sized, sloth-like Nimbadon -- an extinct marsupial that barbarous inwards piece moving overhead inwards the tree tops.

The Riversleigh World Heritage fossil deposits, which bridge the final 24 meg years of Australian history, bring produced many previously unknown kinds of animals such equally Thingodonta, which may bring been a woodpecker-like marsupial; Fangaroo, a tusked kangaroo; Drop crocs, which are foreign leopard-like crocodiles that may bring been arboreal; in addition to Dromornis -- the Demon Duck of Doom, which was i of the largest birds inwards the world.

The Riversleigh Project, which has been a major focus of the palaeontological squad at UNSW, is close to behavior out its 40th annual expedition to Riversleigh.

Once again, the squad expects to uncovering yet to a greater extent than foreign creatures that in i lawsuit populated Australia's ancient rainforests at a fourth dimension when the northern regions of the continent looked to a greater extent than similar Amazonian rainforests than the arid zone the expanse has larn today.

Of item involvement for this year's expedition volition move younger plainly Late Miocene rocks discovered yesteryear the team, assisted yesteryear funding from the Australian Research Council in addition to the National Geographic Society, inwards a remote expanse straight off called "New Riversleigh." These volition fill upward a fundamental fourth dimension menses for the rich, long tape of environmental alter at Riversleigh.

Among the starting fourth dimension tantalising discoveries from "New Riversleigh" has been yet some other bizarre, hyper-carnivorous marsupial that looks similar it mightiness move a younger, far to a greater extent than powerful cousin of the before snail-eating malleodectids.

Like thus many of the foreign creatures continuously existence discovered inwards Riversleigh's rocks, malleodectids went extinct long before humans arrived.

The most in all likelihood crusade was a severe interval of climate alter that began close fifteen meg years agone in addition to ultimately transformed Australia's in i lawsuit widespread, animal-rich rainforests into the to a greater extent than opened upward forests in addition to grasslands of today.

"This climate change-driven transformation inwards Australia's wild fauna over the final fifteen meg years is a timely reminder of the in all likelihood effect of the side yesteryear side wheel of climate change, i nosotros appear to bring triggered ourselves," says Professor Archer.

The question describing the novel marsupials is published inwards the periodical Scientific Reports.

Author: Deborah Smith.| Source: University of New South Wales [May 27, 2016]