New research suggests massive marsupials lived in treetops in early Australia

Nov 28, 2012 by Bob Yirka report
Reconstruction of Nimbadon lavarackorum mother and juvenile (Peter Schouten). Credit: PLoS ONE, doi:10.1371/journal.pone.0048213.g002

(Phys.org)—Researchers from the University of New South Wales and the University of Adelaide in studying fossils of Nimbadon lavarackorum, an extinct wombat-like marsupial, have concluded that the animal likely lived among the treetops of Australia's rain forests approximately 15 million years ago. The new research is based on an analysis of bones discovered in a cave in the Riversleigh in north-west Queensland, the team explains in their paper published in the journal PLUS ONE, and make N. lavarackorum, at approximately 150 pounds, the largest herbivore to have lived in the forested canopies that once flourished in the area.

N. lavarackorum belonged to a family of large known collectively as diprotodontids that all went extinct approximately 11,000 years ago as Australia became drier. N. lavarackorum is believed to have lived during the Middle Miocene, which spans 11.6 to 16 million years ago. The bones examined belong to a collection of 26 different specimens retrieved from a cave in the years following their discovery in 1993. The large group apparently fell into the cave for unknown reasons.

In studying the collection of bones and comparing them to other fossils as well as the of modern animals, the researchers found that parts of N. lavarackorum very closely resemble parts of the modern Koala, which of course lives in trees. Both have very mobile elbow and shoulder joints, big claws and very strong forelimbs – all characteristics necessary for living in trees. They also found that the back end of the animal more closely resembled that of a modern – strong short and strong gripping feet that would have allowed it to hang upside down if need be to reach far hanging fruit. It also had a large bulbous nose that presumably helped it sniff out food.

What's most remarkable about N. lavarackorum the researchers note, is its size, roughly that of modern humans. Virtually all other mammals of its size that lived in the area during the time when much of Australia was covered with rainforests were ground dwellers – it's also the only member of Diprotodontidae believed to have lived in trees.

Explore further: Lead in teeth can tell a body's tale

More information: Black KH, Camens AB, Archer M, Hand SJ (2012) Herds Overhead: Nimbadon lavarackorum (Diprotodontidae), Heavyweight Marsupial Herbivores in the Miocene Forests of Australia. PLoS ONE 7(11): e48213. doi:10.1371/journal.pone.0048213

Abstract
The marsupial family Diprotodontidae (Diprotodontia, Vombatiformes) is a group of extinct large-bodied (60–2500 kg) wombat-like herbivores that were common and geographically widespread in Cenozoic fossil deposits of Australia and New Guinea. Typically they are regarded to be gregarious, terrestrial quadrupeds and have been likened in body form among placental groups to sheep, rhinoceros and hippopotami. Arguably, one of the best represented species is the zygomaturine diprotodontid Nimbadon lavarackorum which is known from exceptionally well-preserved cranial and postcranial material from the middle Miocene cave deposit AL90, in the Riversleigh World Heritage Area, northwestern Queensland. Here we describe and functionally analyse the appendicular skeleton of Nimbadon lavarackorum and reveal a far more unique lifestyle for this plesiomorphic and smallest of diprotodontids. Striking similarities are evident between the skeleton of Nimbadon and that of the extant arboreal koala Phascolarctos cinereus, including the powerfully built forelimbs, highly mobile shoulder and elbow joints, proportionately large manus and pes (both with a semi-opposable digit I) and exceedingly large, recurved and laterally compressed claws. Combined with the unique (among australidelphians) proportionately shortened hindlimbs of Nimbadon, these features suggest adept climbing ability, probable suspensory behaviour, and an arboreal lifestyle. At approximately 70 kg, Nimbadon is the largest herbivorous mammal to have occupied the forest canopies of Australia - an ecological niche that is no longer occupied in any Australian ecosystem and one that further expands the already significant niche diversity displayed by marsupials during the Cenozoic.

Related Stories

Remarkable fossil cave shows how ancient marsupials grew

Jul 14, 2010

(PhysOrg.com) -- The discovery of a remarkable 15-million-year-old Australian fossil limestone cave packed with even older animal bones has revealed almost the entire life cycle of a large prehistoric marsupial, ...

Herds of large treetop marsupials

May 03, 2012

Sheep-sized ancient relatives of modern-day wombats lived in Australia’s treetops 15 million years ago, according to new research led by Dr Karen Black from the University of New South Wales.

Giant prehistoric marsupial found in Northern Australia

Jul 05, 2011

(PhysOrg.com) -- In what paleontologists are describing as a major find, researchers have dug up the remains of a creature that lived some 50,000 to two million years ago. The diprotodon (Diprotodon optatum) as it' ...

Findings show ancient birds died in flash flood

Nov 14, 2011

(PhysOrg.com) -- During a presentation at the Society of Vertebrate Paleontology's 71st annual Meeting in Las Vegas, researchers Gareth Dyke and Darren Naish from the University of Southampton presented their findings of ...

An early ape shows its hand

Aug 08, 2007

Fossils often have provided important insights into the evolution of humans and our ancestors. Even small fossils, such as bones from the hand or foot can tell us much about our ancestor’s and their behavior. Such may be ...

Recommended for you

Fragment of Ice Age ivory lion gets its head back

1 hour ago

Archaeologists from the University of Tübingen have found an ancient fragment of ivory belonging to a 40,000 year old animal figurine. Both pieces were found in the Vogelherd Cave in southwestern Germany, ...

Violent aftermath for the warriors at Alken Enge

Jul 29, 2014

Denmark attracted international attention in 2012 when archaeological excavations revealed the bones of an entire army, whose warriors had been thrown into the bogs near the Alken Enge wetlands in East Jutland ...

Dinosaurs doing well before asteroid impact

Jul 29, 2014

A new analysis of fossils from the last years of the dinosaurs concludes that extra-terrestrial impact was likely the sole cause of extinction in most cases.

User comments : 0