Paleontology: deer-eyed saber-toothed marsupial |

Paleontology: deer-eyed saber-toothed marsupial |

Saber-toothed marsupial with a deer look

A reconstruction of Thylacosmilus atrox.  Photo: Jorge Blanco/American Museum of Natural History/dpa

A reconstruction of Thylacosmilus atrox. photo

© Jorge Blanco/American Museum of Natural History/dpa

Teeth like something out of a horror story – but eyes like a hoofed animal: An extinct predator doesn’t fit into the usual scheme. Scientists now know why.

predators look forward, herbivores have their eyes on the side of their heads. Millions of years ago, a massive, saber-toothed South American predator broke this biological rule – and for a reason, as a research team reports in the journal Communications Biology. The roots of its greatly elongated saber teeth in the upper jaw protruded so far into the skull that there was no room left for forward-facing eye sockets.

The hunter does not make it easy to classify for another reason: he was about the size of a jaguar and looked like a saber-toothed tiger with his huge tusks. But he wasn’t a cat, he was a marsupial. Thylacosmilus atrox lived in South America until about three million years ago. According to researchers, at least 70 percent of its diet consisted of meat. Like the North American saber-tooth cats, he probably went hunting – but with far less 3D-View.

The different alignment of the eyes in hunters and the hunted has a reason: Bei herbivores good all-round vision is essential so they can spot stalking enemies. The front-seated eyes of predators, on the other hand, allow both fields of vision to overlap and thus good three-dimensional vision and precise focusing on potential prey.

Flexible orientation

But how did the deer-eyed saber-tooth get food? The scientists led by Charlène Gaillard from the Argentine research institute Inaglia in Mendoza used CT scans and 3D reconstructions to fathom the visual system of the marsupial saber-tooth. He was therefore probably able to stretch his eye sockets outwards and align them in such a way that the fields of vision of both eyes overlapped noticeably more.

The shifting of the eyes to the sides of the skull had another consequence: they were now close to the masticatory muscles, as the research team explains. So that this does not lead to deformation when eating, the species – like other mammals – developed a special bony structure.

But why this massive remodeling in favor of huge, ever-growing teeth? It is not yet clear whether advantages in acquiring food were decisive or whether Thylacosmilus atrox impressed potential partners with its tusks. “We may consider it an anomaly because it doesn’t fit our preconceived categories of what a proper mammalian carnivore should look like, but evolution makes its own rules,” said Inaglia researcher Analia Forasiepi.


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