Loggerhead sea turtle turtle is debated, but most authors consider it a single polymorphic species. Molecular genetics has confirmed hybridization of the loggerhead sea turtle with the Kemp's ridley sea turtle, hawksbill sea turtle, and green sea turtles. The extent of natural hybridization is not yet determined; however, second-generation hybrids have been reported, suggesting some hybrids are fertile. Although evidence is lacking, modern sea turtles probably descended from a single common ancestor during the Cretaceous period. Like all other sea turtles except the leatherback, loggerheads are members of the ancient family Cheloniidae, and appeared about 40 million years ago. Of the six species
USS Loggerhead (SS-374) these islands, the enemy shore batteries surprised her with hot fire. Evading the bursts of the Japanese shells through skillful maneuvers, "Loggerhead" escaped undamaged. She arrived at Fremantle on 19 July. The end of hostilities on 15 August found "Loggerhead" two days out of Fremantle heading for the Gulf of Siam on her second war patrol. She put in Subic Bay on 22 August, departed for the United States 31 August via Pearl Harbor, and arrived at San Francisco 22 September 1945. "Loggerhead" was decommissioned at Mare Island Navy Yard 16 June 1946 and was placed in the Pacific Reserve