A team of scientists led by the University of Poitiers has identified a new, giant species of long-extinct otter in Ethiopia that was likely the size of a modern lion. While contemporary otters weigh between four and 100 pounds, Enhydriodon omoensis weighted an estimated 440 pounds, making it the largest otter discovered until now. This creature lived between 3.5 and 2.5 million years ago, and was a fierce terrestrial predator.
Traditionally, otters of the genus Enhydriodon were considered to be semi-aquatic animals, feeding on a variety of species common in African freshwater environments, including mollusks, turtles, catfish, or even crocodiles. The scientists analyzed stable oxygen isotopes and carbon in the tooth enamel of the newly discovered member of this group to clarify what type of environment it was inhabiting and what was it was feeding on. Presumably, the relative values of these isotopes should have been close to those of fossil hippopotami and other semi-aquatic animals. However, the researchers were surprised to discover that this giant otter occupied quite a different habitat from its relatives, and had a different diet.
“The peculiar thing, in addition to its massive size, is that [isotopes] in its teeth suggest it was not aquatic, like all modern otters,” said study co-author Kevin Uno, a geochemist at Columbia University. “We found it had a diet of terrestrial animals, also differing from modern otters.” Most probably, E. omoensis was able to hunt prey that consumed a large variety of terrestrial plants, ranging from tropical grasses to vegetation from trees.
In future research, the scientists plan to sample a larger variety of African otter fossils and conduct studies of tooth enamel and the shape and structure of long bones, in order to better understand which place these gigantic creatures occupied in ancient ecosystems, and what was the cause of their extinction about 200 million years ago.
The study was published in the journal Comptes Rendus Palevol. In addition, the authors presented their findings in a short video on YouTube.
By Andrei Ionescu, Earth.com Staff Writer