Complete skeleton of ‘Tasmanian devil on steroids’ reveals secrets of Australian ‘stealth predator’ – Science News
Huge marsupials used to roam in the understory of Australian forests in our geologically recent history.
A snub-faced kangaroo and a giant wombat were among them, but at the top of the food-chain was a marsupial lion, described by naturalist Richard Owen in 1877 as “one of the fellest* and most destructive of predatory beasts”.
Weighing over 150 kilograms, with powerful forelimbs and hands equipped with a large claw, the marsupial lion — Thylacoleo carnifex — was Australia’s top predator until the last one died out somewhere around 35,000 years ago.
Now for the first time, using bones found in Komatsu Cave at Naracoorte in South Australia and Flight Star Cave in the Nullarbor, scientists have been able to analyse a complete skeleton including sections of the tail and clavicles —collarbones.
The discovery has prompted new insights into the “Tasmanian devil on steroids”, and allowed researcher Rod Wells from Flinders University, who published his findings in Plos One today, to learn that the lion was able to sit upright using its rigid tail as a prop.
And rather than chasing down prey, it was a powerful stealth hunter, probably launching attacks from trees or other high perches.
“[And] if you’re going to use the forearms to do strong things like pull yourself up a tree or to fight and hang on to a struggling prey, you need a way of bracing your pectoral girdle, and I think that’s what the strong collarbones are about.”
The picture as it now stands is of an African-lioness-sized predator that could climb trees and pierce its prey with its long claws, possibly dragging its kill back up into the branches to get clear of scavengers.
“I’m a little reticent to use the words ‘drop bear’, but I think it’s very much a stealth predator,” Professor Wells said.
Full picture emerges of ‘Tasmanian devil on steroids’
Professor Wells discovered the first intact skull of a Thylacoleo in 1969. Before then, only one badly preserved and calcified skull had ever been found, from New South Wales in 1966.
“In ’69, we pulled a few rocks out of the cave at Naracoorte and stumbled onto what is now the World Heritage fossil site, and the very first specimen I pick up is the skull of Thylacoleo,” he said.
Over the coming years, Professor Wells and others discovered more pieces of the jigsaw, until a picture emerged of a uniquely Australian beast.
It has the front teeth of its herbivorous diprotodontid cousins, with premolars honed into “bolt-cutter like” blades.
The hind feet are similar to a gigantic brushtail possum, the long front arms and short body like a koala, and the stiff lower back of a Tasmanian devil.
And the last pieces of the puzzle – the tail and collarbones – add weight to the theory that Thylacoleo was something of a forest specialist, able to climb like a koala and hunt like a Tasmanian devil, according to Mike Archer.
“[Professor Wells’] indication that it seems to have had a tail very specialised to being bent upwards, makes sense,” Professor Archer, who didn’t work on this paper, said.
“When you think of a Tasmanian devil on steroids – a lot of steroids – if it’s going to spend time tearing giant kangaroos apart, the idea that it would sit back on its haunches means that its tail really did need to bend like that.”
Professor Archer has done extensive work on a number of Thylacoleo species, and says he’s observed through the fossil record at Riversleigh in central Queensland, the evolution from cat-sized, to leopard-sized, and then to lion-sized apex predator.
‘Blitzkrieg’ or climate change, where did they go?
Professor Archer has also been chemically analysing the teeth structure of Thylacoleo.
His research has led him to the conclusion that the lions’ teeth were specialised to eat C3 herbivores — animals that tend to be browsers of shrubs and low-hanging foliage — rather than C4 herbivores, the grassland grazers.
The remains of tree kangaroos have also been found alongside the skeletons of lions. And although Thylacoleo skeletons have been discovered from arid regions along the Nullarbor Plain, these areas are known to have been covered in dense forest in the past.
Some argue that the arrival of humans in Australia was the catalyst for the demise of megafauna like the lion — known as the “blitzkrieg” hypothesis.
But both Professors Archer and Wells argue that climate change, which in turn led to the aridification of the country and the thinning of forests where Thylacoleo hunted prey, was the more likely culprit.
Around half of Australia’s megafauna had already gone extinct by the time humans arrived, according to Professor Archer.
“The megafauna started disappearing in bouts — little batches disappearing every 10,000 years or so with these big climate fluctuations. Every time we had one of these big hiccups we lost more.
“The confusion has always been that when humans came in, that was around the same time this kind of thing was happening, so it was easy to leap to the first conclusion, despite zero evidence to back it, that humans did it.
“[But] in reality, there simply is no direct evidence that any human butchered any single individual animal of any of the extinct megafaunal animals. Not one. The only evidence we’ve got is that they co-existed.”
Once the fellest and most destructive of predatory beasts was gone, it fell to smaller animals to pick up the slack, according to Professor Wells.
“The stealth predator niche was left to a little tacker — the Tasmanian devil.”
*Archaic English — cruel, fierce, terrible.