Extinct marsupial a fierce hunter

The reconstruction of the skull of an ancient cousin of the Tasmanian tiger, Nimbacinus dicksoni, suggests these carnivorous marsupials were able to hunt and kill prey much bigger than themselves.

Nimbacinus dicksoni (left) and the Tasmanian tiger (right). 

N. dicksoni is a member of the extinct family of Australian and New Guinean marsupial carnivores, the Thylacinidae, which include the recently extinct Tasmanian tiger, Thylacinus cynocephalus.

Once part of a diverse and widespread family of carnivorous marsupials, the thylacinids included at least 11 species - the smallest were the size of a domestic cat and the largest as big as a large dog like a Rottweiler.

Researchers from the University of New England (UNE) and the University of New South Wales have been using virtual reconstruction of a well-preserved N. dicksoni skull found in the Riversleigh World Heritage Fossil Site in Northwest Queensland to learn more about this elusive family.

“For at least 15 million years the thylacinids were key players in Australia’s carnivorous marsupial community,” said Associate Professor Stephen Wroe from UNE.

“While our understanding of thylacinid diversity has greatly improved with new fossil discoveries, our understanding of their ecology has remained limited, in part at least because most fossil species have been represented by very fragmentary remains. The well-preserved skull of the 25- to 15-million-year-old fox-sized N. dicksoni from Queensland is giving us much needed insight.”

Fellow researcher at UNE Dr Marie Attard said despite its fearsome reputation, the Tasmanian tiger largely specialised in killing relatively small prey.

Research conducted with sophisticated virtual 3D reconstruction techniques and computer modelling showed that the Nimbacinus skull was similar in mechanical performance to that of the ferocious spotted-tail quoll than that of the Tasmanian tiger.

“These findings suggest that, unlike its recently extinct relative, the skull of Nimbacinus was adapted to deliver a powerful bite, and that it likely hunted a wide range of prey, up to and likely exceeding its own body mass. Potential prey would have included birds, frogs, lizards and snakes, as well as a wide range of marsupials,” Dr Attard said.

Precisely why the thylacinids became extinct is unclear, but an increasingly arid Australian climate from around 15 million years ago and competition from large dasyurid carnivores such as quolls and Tasmanian devils probably played an important part in their demise.

The study was recently published on PLOS ONE.