“They look prehistoric!” The startled observers of sea turtles on the beaches of French Guiana are closer to the truth than they realise. The first forms of sea turtle appeared during the Lower Cretaceous over 120 million years ago. And the anatomy of certain fossils that have been found suggests that they looked like the turtles which are around today. Isn't there something fascinating in imagining that the ancestors of these marine reptiles could have lived alongside the dinosaurs? And that unlike the dinosaurs, certain species managed to survive the great extinction crisis 65 million years ago which wiped out a considerable number of living organisms from the surface of the planet. Sea turtles have managed to adapt to the major changes in climate and geomorphology that have affected the Earth through the ages, to colonise the oceans, and so arrive in our present day when finally, due to human folly, they are threatened with extinction. The overexploitation of marine resources, the urbanisation of sites where they lay their eggs, the pollution of the oceans, poaching, etc, mean that sea turtle populations are gradually declining and may eventually die out. Today there are seven species all belonging to the order of chelonians, divided into two families: the Cheloniidae and the Dermochelyidae. The latter family only has one species, the leatherback sea turtle (Dermochelys coriacea). As its name indicates this turtle has leathery skin on its back (from the Greek dermo meaning......