We describe here a new species of gigantic otter, Enhydriodon dikikae, sp. nov., from the Pliocene of Dikika, in the lower Awash valley of Ethiopia. The holotype consists of an associated snout and mandible, and is the most complete fossil specimen of a large bunodont otter. In some features, such as its very large size, the loss of anterior premolars, the tall protocone of P4, and the divided paraconid of m1, this species illustrates the culmination of general trends in this group, but the most remarkable part of its dentition is the broad incisor arch and powerful canine battery. The purported distinction between Enhydriodon and Sivaonyx is discussed, and the hypothesis of distinct African and Asian lineages is rejected. Postcranial remains confirm that Enhydriodon dikikae, sp. nov., was probably mostly terrestrial, but its diet remains uncertain, as none of the suggested preys fully explains the anatomical adaptations and relative abundance of this species.
The 200-kilogram 'bear otter' is one of several large carnivores that became extinct around 2 million years ago.
ILLUSTRATION BY VICTOR LESHYK
Extinct giant baboon (Theropithecus brumpti) and giant otter (Enhydriodon sp.) in the Omo River Valley, southern Ethiopia, 3 million years ago. Early hominids also lived in the Omo River Valley during this time period.
Illustration from the California Academy of Sciences.
Enhydriodon dikikae, sp. nov. (Carnivora: Mammalia), a gigantic otter from the Pliocene of Dikika, Lower Awash, Ethiopia: http://dx.doi.org/10.1080/02724634.2011.550356
Early humans linked to large-carnivore extinctions: doi:10.1038/nature.2012.10508