3 million years ago, giant carnivorous otters roamed the savannah

About 3 million years ago, in what is now the Lower Omo Valley, Ethiopia, one of our pre-human ancestors stood warily in the savannah when, seeing otters the size of a lion, took refuge in a tree. In this riverine environment from the end of the Pliocene (5.3 to 2.58 million years ago), Jean Reno Boisseri, of the CNRS, and his team of ogres (Omo Group Research Expedition) Struggling to rebuild, such a scene was possible. Paleontologist Camille Grohe, a member of the team, showed that the dimensions of the teeth and femur of a new species of otter, the otter omo, indicated an animal weighing 200 kilograms. It is the largest otter ever described.

Thus, the members of the hominid living in the area – presumably Australopithecines, some of whom produced stone tools – had to reckon not only with cats and toothed hyenas, but also with giant otters that have no equal today. In fact, the weight of current otters ranges from 2 to 6 kilograms for small clawed otters in South Asia, to 45 kilograms for North Pacific sea otters.

During the Pleistocene (2.58 million years to 11,700 years ago), large otters were common: several species of these very large fossils lived in Eurasia and Africa from the end of the Miocene (23 to 5.3 million years ago), until the Pliocene (5.3 to 2.5 million years ago). years) and thus in the Ice Age. Among them, the African fossil genus enhydroidone He is the most famous. The omo otter is one such species, hence the name Enhydriodon omoensis.

Until then, paleontologists considered, like modern otters, to be of the genus otters enhydroidone They were semi-aquatic, feeding on fish, but also feeding on hard shells and shells such as mollusks, turtles, and even crocodiles. A hypothesis the researchers wanted to test in the case of the giant otter. To do this, they measured the relative proportions of the stable oxygen isotopes found in tooth enamel, as these ratios reflect the terrestrial or aquatic habitats the animal occupies. It turned out that the giant Omo otter was closer to those of hyenas and cats than to semi-aquatic hippos. For their part, the relative values ​​of stable carbon isotopes tell us that the giant Omo otter ate the flesh of herbivores that consume a variety of plants, from grasses (savannah) to tree plants (orchards). It is also possible to feed directly on carcasses. The diversity of their carnivorous diet indicates that they can inhabit many terrestrial habitats, which is in line with the representation of a large, non-aquatic terrestrial carnivore, with hunting behavior similar to that of felids or hyenas. It is a real progress that the ghouls discovered.