 Many other extinct species traditionally placed in the Emydidae are known from the Eocene of North America, Asia, and Europe, but the Old World taxa are likely to be more properly Geoemydidae.The North American genus "Palaeochelys" and probably the trans-Atlantic "Echmatemys", too, would seem to be Emydidae, but their precise relationships to the living genera are indeterminate.The two subfamilies and genera are arranged as follows