Precision and brawn a deadly combination

July 1, 2013, University of New South Wales

The huge canine teeth of Thylacosmilus atrox extended almost into its braincase.
( —A bizarre, pouched super-predator that terrorised South America millions of years ago had huge sabre-like teeth but its bite was weaker than that of a domestic cat, new research shows.

Australian and American marsupials are among the closest living relatives of the extinct Thylacosmilus atrox, which had tooth roots extending rearwards almost into its small braincase.

"Thylacosmilus looked and behaved like nothing alive today," says UNSW , Dr Stephen Wroe, leader of the research team.

"To achieve a kill the animal must have secured and immobilised large prey using its extremely powerful forearms, before inserting the sabre-teeth into the windpipe or of the neck – a mix of brute force and delicate precision."

The iconic North American sabre-toothed 'tiger', Smilodon fatalis, is often regarded as the archetypal mammalian super-predator.

However, Smilodon - a true cat - was just the end point in one of at least five independent 'experiments' in sabre-tooth evolution through the Age of Mammals, which spanned some .

Thylacosmilus atrox is the best preserved species of one of these evolutionary lines - pouched sabre-tooths that terrorised South America until around 3.5 million years ago.

For its size, its huge were larger than those of any other known sabre-tooth.

Smilodon's killing behaviour has long attracted controversy, but scientists now mostly agree that powerful neck muscles, as well as , played an important role in driving the sabre-teeth into the necks of large prey.

Little was known about the predatory behaviour in the pouched Thylacosmilus.

To shed light on this super-predator mystery, Dr Wroe's team of Australian and US scientists constructed and compared of Smilodon and Thylacosmilus, as well as a living conical-toothed cat, the leopard.

These models were digitally 'crash-tested' in simulations of biting and killing behaviour. The results are published in the journal PLoS ONE.

This shows cut away views through the skulls of (A) the sabre-toothed 'tiger' (Smilodon) and (B) the bizarre pouched sabre-tooth (Thylacosmilus). Note the incredibly wide gape and huge canine teeth with roots extending almost into the braincase of Thylacosmilus. Credit: Credit: S. Wroe
"We found that both sabre-tooth species were similar in possessing weak jaw-muscle-driven bites compared to the leopard, but the mechanical performance of the sabre-tooths skulls showed that they were both well-adapted to resist forces generated by very powerful neck muscles," says Dr Wroe.

"But compared to the placental Smilodon, Thylacosmilus was even more extreme."

"Frankly, the jaw muscles of Thylacosmilus were embarrassing. With its jaws wide open this 80-100 kg 'super-predator' had a bite less powerful than a domestic cat. On the other hand - its skull easily outperformed that of the placental Smilodon in response to strong forces from hypothetical neck muscles."

"Bottom line is that the huge sabres of Thylacosmilus were driven home by the alone and - because the sabre-teeth were actually quite fragile - this must have been achieved with surprising precision."

"For Thylacosmilus - and other sabre-tooths - it was all about a quick kill."

"Big prey are dangerous – even to super-predators – and the faster the kill the less likely it is that the predator will get hurt – or for that matter attract unwanted attention from other predators."

"It may not have been the smartest of mammalian super-predators – but in terms of specialisation – Thylacosmilus took the already extreme sabre-tooth lifestyle to a whole new level," says Dr Wroe.

Explore further: Skulls shed new light on the evolution of the cat

More information: … journal.pone.0066888

Related Stories

Skulls shed new light on the evolution of the cat

July 10, 2012

( -- Modern cats diverged in skull shape from their sabre-toothed ancestors early in their evolutionary history and then followed separate evolutionary trajectories, according to new research from the University ...

Marsupial lion tops African lion in fight to death

January 17, 2008

Pound for pound, Australia’s extinct marsupial lion (Thylacoleo carnifex) would have made mince meat of today’s African lion (Panthera leo) had the two big hyper-carnivores ever squared off in a fight to the death, according ...

Komodo dragon has 'pussycat' bite but plenty of punch

October 21, 2011

( -- The world’s largest lizard – the Komodo Dragon – has an astonishingly weak bite, but a new study has revealed that the key to its killing power is a lethal combination of poison, brute strength, ...

Putting new face on ferocious saber-tooth cats

October 26, 2011

It's safe to say Northern Illinois University Biological Sciences Professor Virginia Naples has a fascination with cats. She keeps two tabbies at her Hampshire, Ill. home. She also has focused her research on cats that were ...

Recommended for you

Preventing chemical weapons as sciences converge

November 15, 2018

Alarming examples of the dangers from chemical weapons have been seen recently in the use of industrial chemicals and the nerve agent sarin against civilians in Syria, and in the targeted assassination operations using VX ...

Rare fossil bird deepens mystery of avian extinctions

November 13, 2018

During the late Cretaceous period, more than 65 million years ago, birds belonging to hundreds of different species flitted around the dinosaurs and through the forests as abundantly as they flit about our woods and fields ...


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (5) Jul 01, 2013
Nature doesn't give teeth like that to something that can't bite.
5 / 5 (3) Jul 01, 2013
Cause you say so, moebius... but you sure don't have any knowledge about it.
Studies with smilodons have all the same conclusion: fragile teeth and weak bite. We really don't understand yet how they killed their preys.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.