This sabertooth was an utter horror, with bulging eyes and a murderous smile.

Marina Yu Phillips 기자 승인 2023.03.22 15:17 의견 0

Thylacosmilus atrox, sometimes referred to as the "marsupial sabertooth," was a predator that roamed South America around seven million years ago. It had canines that were so huge that they reached the top of their skull. The hypercarnivore, which consumed at least 70% meat, may have used its tongue to suction out its prey's internal organs. Thylacosmilus, an extinct member of the Sparassodonta, a family of carnivorous mammals related to contemporary marsupials, went extinct around 3 million years ago.

The 200 pound beast had cow-like wide-set eyes, which are very dissimilar from cats' forward-facing eye sockets. The creature was able to view in stereoscopic mode thanks to the peculiar configuration (or 3D).

When looking through eyes like these, objects do not overlap enough for the brain to perceive them as existing in three dimensions. Why the fierce hunter would have such an odd adaptation in its cranium has long baffled scientists.

A study that was just released on March 21 in the journal Communications Biology provides some clarification on how this extinct mammal with a distinctive skull could see and hunt in its prehistoric environment.

Researchers from Argentina and the US examined the arrangement of the nasal cavities in both living and extinct mammals using CT scanning and 3D virtual reconstructions. The team's ability to compare Thylacosmilus' visual system to that of other carnivores or mammals in general as well as examine orbital convergence was made possible by the scans and reconstructions. When looking at nearby objects, the eyes move together and turn inward in this manner.

Thylacosmilus' orbital convergence value was as low as 35 degrees, which is extremely low compared to the average predator's orbital convergence value of 65 degrees.

According to co-author Analia M. Forasiepi of the Instituto Argentino de Nivologa, Glaciologa, y Ciencias Ambientales (INAGLIA), a researcher at the Argentinean science and research agency, "Thylacosmilus was able to compensate for having its eyes on the side of its head by sticking out its orbits somewhat and orienting them almost vertically, to increase visual field overlap as much as possible." Although its orbits were not well suited for 3D vision, it was nevertheless able to attain a visual field overlap of around 70%, which was obviously sufficient for it to be a successful active predator.


The researchers believes that the ability of Thylacosmilus to make up for low orbital convergence may hold the key to understanding how this extinct marsupial's skull was constructed. Early on in their development, the canine growth patterns would have caused the eye sockets to shift away from the face, giving rise to the wide-set eyes seen in adulthood.

Without initially facing those gigantic canines, it is impossible to comprehend the cerebral arrangement of Thylacosmilus, according to research co-author and INAGLIA Ph.D. student Charlène Gaillard. "They weren't simply big; they were constantly expanding to the point where the canine roots extended over the tops of their skulls. One result of this was that the orbits could not be placed in their typical carnivore position on the front of the face.

Thylacosmilus changed more than just the arrangement of the eye sockets to make room for its large canines. Their eyes are significantly more in close proximity to their chewing muscles, which run the risk of becoming malformed while they consume. The placement of the eyes on the side of the skull also places them near the chewing muscles of the mouth, possibly leading to a distortion of those muscles. In order to regulate this, some mammals, such as primates and Thylacosmilus, have evolved a bony structure that seals off the eye sockets from the side.

The reason why the animal would acquire enormous, continuously expanding teeth that required the animal's entire cranium to be redesigned raises a new question.

Gaillard speculated that it might have made predation simpler in some unidentified way. "Unlike rodents' incisors, Thylacosmilus' canines did not deteriorate over time. They merely appear to have kept expanding at the root, finally reaching practically the back of the head.

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