In prehistoric Ethiopia, otters were as big as lions

About three million years ago, One of our early hominin ancestors fed some leaves along a river bank in what is now Ethiopia. And there it was — 440 pounds of fur, with teeth strong enough to crush bone. An otter the size of a large lion was wandering in the thick weeds before bending down to drink from the muddy riverbank. Our ancestor has once again infiltrated the surrounding forests. No matter how cute a giant otter is (or maybe not), you don’t want to cross an animal that big.

otter Enhydriodon omoensisis the largest size ever found. New study In the French magazine Ballyful Reports He was the first to classify the species, and named it after the Ethiopian Omo River, where its remains were discovered. While the study calls otters “lion-sized,” paleontologist Margaret Lewis of Stockton University in New Jersey thinks “that’s kind of an underselling.” She says “bear otter” is perhaps a better term to sum up how big these foxes are. Well, grizzly otter is.

But the otters’ sheer size wasn’t the only thing that surprised the study’s lead author, carnivore specialist Camille Grouhy of the University of Poitiers in France. Testing on oxygen and carbon isotopes collected from the teeth of otters shows that unlike their modern semi-aquatic descendants, Enhydriodon omoensis He lived primarily on Earth. “I wasn’t really expecting that,” Grohe says.

The first excavation expedition to the lower Omo Valley was in the 1930s. Since 1967 it has been the site of almost continuous scientific excavations. Courtesy Omo Group Research Expedition (OGRE)

Located in the southwestern corner of Ethiopia, the Lower Omo Valley is one of the stars of paleontology. Not far from the place of fragmented remains Enhydriodon omoensis Paleontologists, often with the help of local residents, have discovered many fossils belonging to our earliest hominin ancestors. Omo Valley is one of the oldest known sites [sites] Ethiopian paleontologist Yohannes Haile Selassie of Arizona State University says, “Back in the early 20th century, European explorers described seeing fossils spread out on hillsides along the Omo River. Then, in 1967, an international team of scientists surveyed the area” when They started finding all kinds of things,” says Haile Selassie. Among those discoveries, in the early 1970s, was a huge femur.”[Researchers] They knew it was a type of carnivore, but it was so big, they didn’t think it was an otter. Haile Selassie adds that it has been in the collection “in the National Museum of Ethiopia since then. The National Museum in Addis Ababa houses thousands of fossils unearthed from Omo (including the fossilized remains of the hominin we know today as “Lucy”). In April 2019, it went Grohe’s hunt for ancient carnivores – in the museum’s lush storage area.

“This is where you find really cool stuff, in museums,” Grohe says. For about three weeks, Grohe worked in the museum’s basement, analyzing hundreds of carnivorous Omo fossils. “I wasn’t just looking at otters,” she says. “I was looking at the overall diversity [and] Checking if the samples we have in the database also match the samples we had in the drawers. “

In the end, I stumbled upon a “stranger” bone, the same one that paleontologists discovered in the 1970s. Looks like it came from an otter, but They were really long and didn’t really match the aquatic mammals,’ which generally have shorter bones to help the animals swim. Grohe picked up some other fossils – some teeth and parts of the skull – that also didn’t seem to match any known species of otters.

Giant prehistoric otter weighed nearly five times as much <em> Australopithecus afarensis </ em> a type of hominin ” lucy=”” belonged=”” to.=”” width=”auto” data-kind=”article-image” id=”article-image-91163″ src=”https:// ZW5zaXMsIGxhcmdl/c3Qgb3R0ZXIgZXZl/ciBmb3VuZCwgdmlz/dWFsLmpwZw.jpg”/><figcaption class=The prehistoric giant otter weighed nearly five times its own weight Australopithecus afarensiswhich are the types of hominids that Lucy belongs to. © Sabine Riffaut, Camille Grohé/Palevoprim/CNRS – University of Poitiers

In July 2019, Grohe returned to Ethiopia, this time to the lower Omo Valley to find out where the fossils were discovered. “It’s a long way,” says Kevin Ono of Columbia University, another author on the study. “Imagine driving through Utah without a single paved road.” With 10 cars full of paleontologists and supplies, it takes four days to reach Omo from Addis Ababa. Located along the Chai River, the barren valley is dotted with stunning hills. “It feels like the badlands of South Dakota,” Ono says.

While paleontologists searched for fossilized carnivores, armed security personnel were keeping their eyes peeled for their living siblings. Lions chasing weeds. Crocodiles roam the river. One morning in 2014, Ono remembers seeing lion footprints in the tracks of the team’s new tires.

Fortunately, my puppy avoided any encounters with live carnivores in 2019. Instead, she found some giant fossilized clams. guess it Enhydriodon omoensis It was semi-aquatic, “I thought it could be a good meal for this otter,” she says. But when she analyzed some otter teeth in her lab, she found something amazing.

In collaboration with Uno, Grohé and a team of scientists extracted small amounts of enamel from Enhydriodon omoensistheir teeth, they are Tested for carbon and oxygen isotopes. Grohe was surprised to discover that the isotopes were from largely terrestrial sources. “It was fed a wide variety of [land-based] prey,” says the puppy; the patterns were similar to those found in cats and large hyenas today. But whether the otter was hunting or burrowing, the puppy is unsure.

The Omo River is about 500 miles long, and runs through southwestern Ethiopia.
The Omo River is about 500 miles long, and runs through southwestern Ethiopia. Rod Waddington/CC BY-SA 2.0

Enhydriodon omoensis It wasn’t the only giant otter in Africa during the Pliocene and the late Miocene, roughly seven million to two million years ago, but it was one of the last. “I was expecting it to have a very narrow range of habitats that could explain why it went extinct,” Grohe says. Since otters have a large habitat and can eat just about anything, “I don’t know now why they’re extinct.”

Lewis takes this question a step further – if a generalist like Enhydriodon omoensis They didn’t make the evolutionary cut, how did our ancestors manage to survive? “It’s scary enough if you only think about surviving with lions and hyenas and leopards and all living things,” but when you add three species of saber-toothed cats, giant otters, and all the other terrifying things of the Ice Age, “it’s scary enough,” he says. It’s amazing [our hominin ancestors] Through this, she says.

Grohe isn’t quite sure what would have happened in a meeting between our early ancestors and Enhydriodon omoensis. “I don’t know if he would necessarily be aggressive towards you,” Grohe says. But she says nonetheless, “I think, like [with] A bear, don’t go near it.” Ono agrees, joking, “If I encountered this fox, I would have liked our meeting to be from a distance.”