Extinct Otter Species As Huge As A Modern Lion Newly Identified In Ethiopia Enhydriodon Omoensis

A new species of long-extinct otter, that was as huge as a modern lion, has been identified in Ethiopia. The extinct otter is the largest otter ever described. It weighed an estimated 200 kilograms, and would have rubbed elbows. The extinct animal lived alongside our much smaller ancestors 3.5 million to 2.5 million years ago, and competed with them for food. The study describing the findings was recently published in the French scientific journal Comptes Rendus Palevol. Some modern otters include the Asian small-clawed otter, South American giant otter, and North Pacific sea otter. These weigh 1.8 to 5.9 kilograms, up to 32 kilograms, and 45 kilograms, respectively. 

In a statement released by the Earth Institute at Columbia University, Kevin Uno, one of the co-authors on the paper, said the peculiar thing, in addition to its massive size, is that isotopes in its teeth suggest it was not aquatic, like all modern otters. He added that the researchers found the offer had a diet of terrestrial animals, unlike modern otters. Camille Grohé is the lead author on the paper. 

Genus Enhydriodon Is Best Known Among Giant Otters

From about six million to two million years ago, several giant otters have populated Eurasia and Africa. The extinct genus Enhydriodon is the best known among these giant otters. This is because its remains, although fragmentary, have been found in many locales, particularly in eastern Africa. The scientists have named the newly described species Enhydriodon omoensis, after southwestern Ethiopia’s Lower Omo Valley, where the remains of the extinct animal were uncovered. 

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How Did Scientists Estimate The Body Mass Of Enhydriodon omoensis?

Several international excavation teams discovered the fossils over the years. The study authors based their body mass estimates on the dimensions of the animals’ teeth and femur. 

Traditionally, otters of the genus Enhydriodon have been considered feeding on molluscs, turtles, crocodiles and catfish, and semi-aquatic. All the animals the genus Enhydriodon used to feed on are common in African freshwater environments. 

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How Can An Animal’s Habitat Be Determined From Fossils?

Study co-author Kevin Uno tested the idea of the newly identified animal being semi-aquatic and feeding on certain animals by analysing stable isotopes of oxygen and carbon in the tooth enamel of Enhydriodon omoensis. One may determine the habitat occupied by an animal using the relative values of stable oxygen isotopes. 

The Giant Otter Was Similar In Size To Modern Big Cats 

The values in the fossil otter should presumably have been close to those of fossil hippos or other semi-aquatic animals. Instead, the researchers found the giant otter had values similar to those of terrestrial mammals, in particular big cats and hyenas from the Omo fossil deposits. The Omo remains are a collection of hominin bones discovered between 1967 and 1984 in Omo National Park in southwestern Ethiopia, and were recovered by a scientific team from the Kenya National Museums. The fossils were excavated from the Omo Kibish formation near the Omo River, and are some of the oldest known human fossils. 

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What Prey Did Enhydriodon omoensis Feed On?

The scientists determined the type of prey Enhydriodon omoensis consumed by analysing the carbon isotopes in teeth. They found that Enhydriodon omoensis was able to hunt prey that consumed a wide variety of terrestrial plants, from tropical grasses to vegetation from trees. 

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In order to understand what place these gigantic otters occupied in past ecosystems, and the causes of their extinction, about two million years ago, the authors aim to sample African otter samples more widely and conduct studies of tooth enamel and the shape and structure of long bones.