The ‘Marsupial sabertooth’ had huge fangs that grew on top of its skull

(CNN) An unusual animal with canine teeth similar to those a A saber-toothed cat with the wide eyes of a cow lived in South America about 5 million years ago.

In order to successfully hunt prey and survive, the “marsupial sounding tooth,” called Thylacosmilus atrox, was adapted to see the world in a unique way, according to new research, because its canine tooth hanging from its mouth was so large that its roots wrapped over the top of its mouth. her skull.

“Not only were they large, but they were constantly growing, so much so that the roots of the tusks continued over the heads of their skulls,” said lead study author Charlene Gaillard, a PhD student at the Argentine Institute of Physiology. Glaciology and Environmental Sciences of Mendoza, Argentina, in a statement accompanying the release of new research on Thylacosmiluss.

The study, which describes findings based on an analysis of the animal’s skull, was published in the journal Communication biology.

Researchers believe that Thylacosmilus was a hypertrophic animal–an animal with a diet of about 75% meat–similar to lions. But unlike most predators with frontal eyes and full 3D vision to help them track prey, the creature had eyes on the side of its head like a horse’s.

The location of the animal’s large tusks meant that there was no place for the animal to have eyes on the front of its face. The eyes do not survive in the fossil record, however The eye sockets in skulls could help researchers determine more about the visual physiology of the extinct creatures.

Visual depth perception

Gaillard used 3D virtual reconstructions and computed tomography scans to analyze the skull of Thylacosmilus and compare it with other mammals, especially carnivores.

determined that the eye sockets of Thylacosmilus were more vertically oriented than other similar animals to achieve depth perception.

“Thylacosmilus had panoramic vision,” she said. “One way to imagine it is to take a picture of a panoramic view with your cell phone. … The resulting image is a wide-angle view of the landscape, but it’s hard to separate individual elements of the landscape and focus them on.”

It can overlap about 70% of its visual field, enough to make it a successful predator, said study co-author Analia M. Voracibe, a researcher with the National Council for Scientific and Technical Research, or CONICET, Argentina’s science and research agency.

Analysis of the skeleton of Thylacosmilus, along with the researchers’ understanding of its vision, showed that the animal was unable to stalk prey at high speed. An ancient relative of the marsupial It resembles a large cat predator and weighs about 220 lb (100 kg). However, Thylacosmilus was more likely the animal “lying in ambush, blending into the landscape and waiting for a potential prey item to appear,” said study co-author Ross D. McPhee, senior curator of mammalogy. at the American Museum of Natural History in New York City, in a statement.

With a prey animal in sight – and range, Thylacosmilus’ huge fangs were capable of delivering a fatal blow by slamming into its target.

Skull adaptations

part of the An unusual adaptation to accommodate massive teeth, the skull of Thylacosmilus also featured a bony structure that closed the eye sockets from the side to prevent deformation and excessive swelling while eating, since the eyeballs were so close to the masticatory muscles.

Researchers believe Thylacosmilus became extinct due to environmental changes that altered the landscape of South America 3 million years ago, causing prey to become scarcer, McPhee said. Thylacosmilus followed suit, and once it disappeared, saber-toothed cats from North America moved south to replace them as predators. (For comparison, these cats are saber-toothed, a.k.a Smilodon, which lived across North America, became extinct only 11,000 years ago.)

The Thylacosmilus study created more questions than answers, such as why it was the only animal with teeth of this size that required skull modifications.

“It may have made predation easier in some unknown way,” Gillard said. “The canines of Thylacosmilus did not wear away like the incisors of rodents. Instead, they appear to have continued growing at the root, eventually extending almost to the back of the skull.”

The researchers want to explore how the animal uses other senses to help it search for prey.

“One thing is clear: Thylacosmilus was no obsessive nature… In its time and place, it seems, it managed to survive as an ambush predator,” Vorasipe said. “We might consider it an anomaly because it doesn’t fit our preconceived categories of what a mammalian carnivore should look like, but evolution makes its own rules.”