The seven species of extant sea turtles show a diversity of diets and feeding specializations. Some of these species represent distinctive ecomorphs that can be recognized by osteological characters and therefore can be identified in fossil taxa. Specifically, modifications to the feeding apparatus for shearing or crushing (durophagy) are easily recognizable in the cranium and jaw. New sea turtle fossils from the Miocene of Peru, described as a new genus and species (Pacifichelys urbinai n. gen. and n. sp.), correspond to the durophagous ecomorph. This new taxon is closely related to a recently described sea turtle from the middle Miocene of California, USA (Pacifichelys hutchisoni n. comb.), providing additional information on the osteological characters of this lineage. A phylogenetic analysis of Pacifichelys and other pan-chelonioid sea turtle lineages shows that at least seven lineages independently evolved feeding specialized for shearing or crushing. The iterative evolution of these morphologies is plausibly linked to ecological factors such as the development of seagrass communities and the opening of niches through extinction that occurred from the Cretaceous to the Miocene.