Prehistoric sea cow was eaten by a croc and a shark, newly discovered fossil reveals

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A rare fossil has provided a snapshot of what was an exceptionally bad day for a prehistoric sea cow.

The now-extinct species of dugong, a manatee-like marine mammal, was swimming in the sea about 15 million years ago when it was preyed upon by two animals: a crocodile and a tiger shark. The latter left one of its teeth impaled in the sea cow’s body.

By analyzing the fossil, discovered in Venezuela, researchers were able to piece together how the sea cow, which belonged to an extinct group of animals known as Culebratherium, perished.

Their study, published Thursday in the Journal of Vertebrate Paleontology, captures a moment in time that provides a unique insight into how the food chain worked during the early and middle Miocene epoch, 11.6 million to 23 million years ago.

“It’s very rare to find evidence of two predators on a single specimen,” said lead study author Aldo Benites-Palomino, a PhD candidate in the department of paleontology at the University of Zurich in Switzerland. “It shows why we should be exploring fossils in tropical regions like (Venezuela).”

Anatomy of an attack

The fossilized remains—a partial skull and 13 vertebrae, or spine—revealed three types of bite marks. Their shape, depth, and orientation suggested they were made by two predators: a small to medium-sized crocodilian and a tiger shark.

The crocodile-like creature attacked first, according to the study, with deep tooth impacts into the sea cow’s snout, suggesting it tried to grab that part of the dugong’s face to suffocate it. Two other large, curved incisions indicate that the crocodile dragged the sea cow, tearing at its flesh.

The striations and cutting of the fossils suggested that the croc performed a “death roll,” a spinning behavior to subdue prey that is also seen in living crocodilian species.

“This type of marking is only produced by biting events in which subsequent tearing, rolling, or grasping actions are executed,” the study authors noted.

The manatee was then ripped off by a tiger shark, which has narrow, serrated teeth. Differentiating between signs of active predation and escape can be challenging, but according to the study, the bite marks all over the sea cow’s body and irregular distribution, along with variation in depth, suggested to the researchers that it was the behavior of a scavenger, such as a tiger . shark.

Scientists confirmed the shark’s identity by discovering an isolated tooth stuck in the sea cow’s neck that belonged to an extinct species of tiger shark, Galeocerdo aduncus.

“I had to work as a forensic scientist,” Benites-Palomino recalled.

However, the study noted that given the fragmentary nature of the skeleton, it was not possible to rule out other scenarios for the sea cow’s death.

Dean Lomax, a paleontologist at the University of Bristol and the University of Manchester in the UK who was not involved in the research, said he agreed with the study’s findings but said it was difficult to distinguish between predatory behavior and active prey.

“For example, it may not be unreasonable to think that the dugong was already dead, perhaps it was floating and (was) bloated, and then was eaten (nailed) by the crocodilian and by the shark(s) at different times,” Lomax said . , author of “Locked in Time: Animal Behavior Unearthed in 50 Amazing Fossils,” via email.

“Unless we have direct evidence of the dugong inside the croc (as the final meal) or the croc and dugong dying in the middle of the attack, it’s always inherently rare to say 100% whether this was definitely the result of an active attack on cleaning,” added Lomax.

Accidental discovery of fossils

Sea cows at that time could be up to 5 meters (about 16 feet) long, Benites-Palomino said, and their fatty tissue would have been a good source of food.

Today, crocodiles, orcas and sharks prey on dugongs and manatees, mostly targeting the young, as the adults are difficult to kill due to their size. It is not clear exactly what type of crocodilian would have preyed on the sea cow – it could have been an extinct type of caiman or gharial, known for a long, thin snout, but it would have been large – 4 to 6 meters (about 13 meters ). up to 20 feet) in length.

“There are several candidates. South America was a paradise for crocodilians back then,” added Benites-Palomino.

A farmer south of the city of Coro, Venezuela, first noticed the remains of a sea cow in a location where fossils had not previously been discovered.

“Initially, we were unfamiliar with the geology of the site, and the first fossils we unearthed were parts of skulls. It took us a while to determine what these are – manatee skulls, which have a rather strange appearance,” said Marcelo Sánchez-Villagra, co-author of the study and professor of paleobiology and director of the Paleontological Institute and Museum at The University of Zurich, in a statement.

Benites-Palomino said the rare find showed the value of fossil hunting in “non-classical” South America.

“We’ve been going to the same fossil sites in North America and China for a long time, but every time we work in these new areas we’re constantly finding new fossils.”

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