Charles Albert Repenning 1976 <p>Two lineages of the "crab-eating" otter <i>Erihydriodon</i>, from the Old World Miocene and Pliocene, are suggested by the fossil record. One appears to lead to the late Pliocene <i>Enhydriodon sivalensis</i> from Villafranchian-equivalent beds in India and can be characterized by the presence of a parastyle on P⁴ and by the location of the protocone of this tooth, which is located as far lingually as is the hypocone. In the other lineage no parastyle is developed on P⁴, the anteroposterior length of the carnassial blade is progressively reduced while the transverse width is increased, and the protocone of P⁴ remains in its primitive position anterolateral to the hypocone. The second lineage, insofar as it is known, seems to lead toward the living sea otter <i>Enhydra</i>, particularly so because of the evolutionary direction shown by two species of <i>Enhydriodon</i> from the late Miocene and late Pliocene of California.</p> application/pdf en U. S. Geological Survey Enhydra and Enhydriodon from the Pacific Coast of North America article