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
Loggerhead Key done to provide the monkeys a place to breed, to supply the animals for medical research laboratory experiments. Around 1,322 of the monkeys existed on the island between 1987–1990. The Dry Tortugas Light is a lighthouse located on Loggerhead Key. It began operations in 1858 and was decommissioned in 2014. The Carnegie Marine Biological Laboratory, also referred to as the Tortugas Laboratory, was a marine biology laboratory and research facility constructed on the northern end of Loggerhead Key that operated from 1904 to 1939. It was constructed and operated by the Carnegie Institution of Washington. The Carnegie Marine Biological Laboratory