[2] A second nominal Leptophoca species, L. amphiatlantica, was coined for specimens found on both sides of the North Atlantic.

The humerus indicates primitive features, such as a reduced lesser tubercle, a straight diaphysis, and intermediate projection of the deltopectoral crest.

Skull features including a long rostrum and simplistic teeth indicated that Leptophoca had a feeding mechanism that indicates rapid jaw closure, which benefits a grip and tear feeding strategy for grasping and shaking prey.

Leptophoca was a carnivore that fed on medium to large-sized endothermic prey which includes seabirds, large fish, and other marine organisms.

Based on ecomorphotype analysis, Leptophoca most likely resided between 50-100 meters in coastal habitats over continental shelves, characterized by being sunlit and relatively warm in addition to being well mixed between winds and currents.