This Historical Sea Cow Was Killed by a Croc and Eaten by a Shark

This Historical Sea Cow Was Killed by a Croc and Eaten by a Shark

By Meghan Bartels

The circle of life is gorgeous and grotesque—generally so grotesque that it makes the fossil document downright macabre, hundreds of thousands of years after the actual fact.

That’s what occurred with an historical manateelike animal whose stays have been uncovered in western Venezuela in 2019. The specimen didn’t draw a lot curiosity at first; it isn’t notably effectively preserved. However as scientists seemed nearer, they realized the creature’s cranium elements and vertebrae have been riddled with chew marks—from two very completely different mouths.

“As soon as you start to take a look at the details, you realize that there is something really special about the animal,” says Aldo Benites-Palomino, a final-year Ph.D. scholar in paleontology on the College of Zurich. He’s a co-author of a paper revealed on August 29 within the Journal of Vertebrate Paleontology that reviews the discover and makes use of the fossilized proof of violence to begin piecing collectively how species interacted on this little-studied area of South America.

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“Bite marks are really interesting to study because you don’t feel like a paleontologist—you feel mostly like a forensic specialist,” Benites-Palomino says. The case at hand:

Sufferer: one sea cow, genus Culebratherium—maybe 16 toes lengthy, though the fossil isn’t effectively sufficient preserved for the researchers to make sure.

Time of dying: early to mid-Miocene, 23 million to 11.6 million years in the past.

Scene of the crime: an historical shoreline of brackish water and mangrovelike forests.

Benites-Palomino and his colleagues started their investigation by figuring out three various kinds of chew wounds on the fossilized bones. One sort of chew mark left small, round indentations on the ocean cow bone. One other left deep, spherical pits with an incision arcing off them. And yet one more left slender, slitlike marks with triangular imprints.

After which there was what paleontologist Sally Walker of the College of Georgia, who was not concerned within the new analysis, calls a “smoking tooth”: a fossilized chomper discovered embedded within the fossil between the ocean cow’s neck and ribcage. The stray tooth, from an extinct tiger shark referred to as Galeocerdo aduncus, means that the slitlike marks have been left by the identical shark scavenging on the ocean cow’s stays, the research’s researchers say. This type of scavenging can be doubtless why the skeleton is so fragmentary: messy eaters in all probability tore off items of the carcass and carried them away. Walker says that she’d prefer to see proof that shark enamel are unusual within the space to rule out a coincidental discover, nevertheless.

In the meantime Benites-Palomino and his colleagues attributed the primary two forms of chew marks to some form of crocodilian—though pointing the finger at a selected suspect species is difficult, he says. That’s as a result of the realm on the time was what he calls “a paradise for crocodilians” and since members of this order usually have equally sized enamel even when their physique dimension varies. “Unless it’s something gigantic or something tiny, it’s really difficult” to pinpoint what species was doing the biting, Benites-Palomino says.

The researchers posit that the crocodilian first snapped on the sea cow’s snout—leaving the small round indentations—then snatched on the animal and used its tail to spiral its physique and tear on the animal in what scientists time period a “death roll.”

The dying roll is a standard tactic amongst almost all trendy crocodilians, says Stephanie Drumheller, a paleontologist on the College of Tennessee, Knoxville, who was not concerned within the new analysis. Despite the fact that it’s a believable method for an historical crocodilian to have used, she’s not satisfied the habits ties to the curving chew marks as tightly because the researchers recommend, nevertheless. “Positively lining up bite marks with specifically the death roll—I’m not comfortable with that,” she says. “It’s not a nice, neat one-to-one.”

In the long run, the workforce’s story of what precisely occurred to the battered sea cow is only a speculation, Walker emphasizes, and one that will by no means be confirmed. However no matter precisely befell the unfortunate creature all these hundreds of thousands of years in the past, its destiny speaks to the complexity of its ecosystem and is a compelling reminder, all three scientists say, that historical meals webs have been simply as intricate as trendy ones. “Bite marks give us this amazing window into the food webs in these extinct ecosystems,” Drumheller says.

And since the formation the ocean cow was present in has been little or no studied, there’s nonetheless quite a bit to study this Venezuelan space’s distant previous, the scientists behind the brand new analysis say. It’s simply considered one of a bunch of compelling discoveries made in South America, says Benites-Palomino, who hails from Peru and works with colleagues from throughout the continent. “I’m in the middle of the start of this golden age of paleontology in South America,” he says. “We’re discovering quite a lot of material in every single country.”