2017-04-12 10:51:03
Trilobites: Saber-Toothed Cats Paid a Stiff Price for Lunch

10:51, April 12 253 0

Some 12,000 years ago, the saber-toothed cat stalked grasslands across the Americas, pouncing on unsuspecting horses and bison before sinking its ferocious fangs into their throats and bellies.

But catching that prey came at a price. The big cats, known as Smilodon fatalis, suffered injuries to their shoulders and lower backs as a result of their hunting, a new study suggests. These battle wounds contrasted with those obtained by another top Pleistocene predator, the dire wolf. The wolves, which chased their prey over long distances and often to exhaustion, instead strained their necks and paws while on the hunt.

Paleontologists already thought smilodons ambushed their prey and dire wolves pursued them, but the new study provides further support for the creatures’ suspected predatory habits using evidence left behind on their own bones. It also suggests that the smilodon’s hunting method might have been riskier than the dire wolf’s. The paper was published Monday in the journal Nature Ecology and Evolution.

Caitlin Brown, a doctoral candidate at the University of California, Los Angeles, and lead author of the study, along with her colleagues analyzed more than 35,000 saber-toothed cat and dire wolf bones retrieved from the La Brea Tar Pits in Los Angeles.

During the era in which the saber-toothed cats lived, the tar pits were death traps for predators and prey alike. Oftentimes a large herbivore like a mammoth or mastodon would wander into the thick, black pools and become stuck. Carnivores eager for what seemed like an easy meal also waded into the goop, only to fall victim themselves.

The tar kept the bones well preserved, albeit stained a dark color. A medical researcher at the Natural History Museum of Los Angeles County, where the samples are kept, had previously found signs of trauma on about 2,000 of the bones. The entire collection represented at least 340 smilodons and 370 dire wolves.

“Most of the injuries we found were not broken bones or signs of major trauma,” Ms. Brown said, “they were signs that the muscles were overworked or arthritis was in the area.”

Using computer software designed to map concentrations of crime in cities, the team constructed injury hot spot maps for the two predators. The maps highlighted where on their skeletons the animals were damaged most often. They showed that the smilodon was more likely to have hurt its shoulder blades and some of its lower thoracic and lumbar vertebrae than its other bones, and the dire wolf was more likely to have injured its cervical vertebrae, ankles and toe bones than other parts of its body.

They found signs of damage on about 4 percent of the saber-toothed cat bones and 3 percent of the dire wolf bones. But 56 percent of all injuries on the saber-toothed cat occurred on the spine — with most occurring in the lower parts — and about 65 percent of all dire wolf injuries occurred on the limbs, mostly the paws.

“An ambush predator lying in wait was more likely to be injured than something that was running through the terrain,” Ms. Brown said.

The damaged bones, she said, reflected the predators’ different hunting methods. The saber-toothed cat most likely suffered damage to its lower back while it twisted and turned trying to wrestle large prey to the ground with its massive forelimbs. The dire wolves may have had their limbs stepped on or kicked as they chased their prey.

The wolves also may have suffered more neck injuries than the smilodons because they used their jaws to snap at their prey and shred them apart indiscriminately, which would have opened them up to a retaliatory kick, while the smilodon first used its powerful paws to strike its target before delivering a killing bite.

While the bones mostly showed how the saber-toothed cats and the dire wolves were different, they also displayed one way the predators were the same: Neither could resist a free lunch stranded in tar.