Ancient Saber-Toothed Super-Predator Hunted with Precision and Brawn

Millions of years ago, a pouched super-predator stalked through South America. This creature used to stab its prey with its huge, saber-like teeth. Now, scientists have learned a little bit more about this predator's hunting strategies, which may reveal a little bit more about saber-toothed animals in general.

Known as Thylacosmilus atrox, this animal looked and behaved like nothing alive today. Its closest living relatives are the Australian and American marsupials, but even they fail to show exactly what this creature was like during its lifetime.

While most people think of the saber-toothed tiger, Smilodon fatalis, when they think of a saber-toothed animal, the tiger was just the end point of at least five independent "experiments" in saber-tooth evolution. Thylacosmilus atrox actually has larger teeth proportionally to its body than the saber-tooth tiger, making it one of the more interesting saber-toothed animals to study. With its powerful neck muscles and jaw muscles, the creature likely utilized its teeth to help kill its prey.

In order to learn a little bit more about this creature, though, scientists constructed and compared sophisticated computer models of both the saber-toothed tiger and Thylacosmilus. These models were then "crash-tested" in simulations of biting and killing behavior. This allowed the scientists to determine exactly how these creatures may have subdued their prey.

"We found that both saber-tooth species were similar in possessing weak jaw-muscle-driven bites compared to the leopard, but the mechanical performance of the saber-tooths' skulls showed that they were both well-adapted to resist forces generated by very powerful neck muscles," said Stephen Wroe, leader of the research team, in a news release. "But compared to the placental Smilodon, Thylacosmilus was even more extreme."

It turns out that Thylacosmilus had a bite that was less powerful than a domestic cat. Yet its skull easily outperformed the saber-tooth tiger in response to strong forces from hypothetical neck muscles. In other words, Thylacosmilus first pinned its prey to the ground with its powerful forearms and then, with great precision, bit down with its relatively-delicate teeth. This allowed it to make a quick kill.

"It may not have been the smartest of mammalian super-predators-but in terms of specialization, Thylacosmilus took the already extreme saber-tooth lifestyle to a whole new level," said Wroe in a news release.

The findings are published in the journal PLOS One.