Taxonomy
''Leptophoca lenis'' was coined by Frederick True for a humerus from the Calvert Formation of Maryland. Later, Clayton Ray referred ''"Prophoca" proxima'' from the Antwerp region, Belgium, to ''Leptophoca''. A second nominal ''Leptophoca'' species, ''L. amphiatlantica'', was coined for specimens found on both sides of the North Atlantic. A 2017 study found ''proxima'' and ''lenis'' to be the same species, rendering ''proxima'' the epithet of the ''Leptophoca'' type species, but evidence for the validity of ''L. amphiatlantica'' was deemed weak, rendering ''amphiatlantica'' a ''nomen dubium'' within ''Leptophoca''.Description
''Leptophoca'' is described as being similar in size to the modern-day harp seal. The humerus indicates primitive features, such as a reduced lesser tubercle, a straight diaphysis, and intermediate projection of the deltopectoral crest. A deep tendon groove in the forelimb also suggests increased manus flexion. All these features show an increased flexibility of the forelimbs, indicating that ''Leptophoca'' would mainly utilize its forelimbs for aquatic and terrestrial locomotion and aid in propulsion, braking, and steering underwater. This contrasts with extant phocids, which mainly utilized their hindlimbs for propulsion while their forelimbs were limited in flexibility. 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. KIENLE, S. S., & BERTA, A. (2018). THE EVOLUTION OF FEEDING STRATEGIES IN PHOCID SEALS (PINNIPEDIA, PHOCIDAE). Journal of Vertebrate Paleontology, 38(6), 1–13. https://www.jstor.org/stable/26765803References
{{Taxonbar, from=Q16948102 Miocene pinnipeds Phocines Prehistoric carnivoran genera Prehistoric pinnipeds of North America Fossil taxa described in 1906