Macrochelys


Macrochelys is a genus of very large freshwater turtles in the family Chelydridae, native to the Southeastern and Midwestern United States. Only a single extant species was recognized until 2014, when a study divided it into two or possibly three species. These turtles are easily recognized by three distinct dorsal ridges with raised spikes.

Extant species

Traditionally, only a single extant species was recognized, but following reviews, two species are now recognized: Anatomical differences between the two species of Macrochelys include the shape of the caudal notch at the rear of the carapace and the angle of the squamosal bone at the rear of the skull. The two species are estimated to have diverged less than 3.5 million years ago.
A third species has been proposed, but its validity is disputed. Neither the Reptile Database nor IUCN's Tortoise and Freshwater Turtle Specialist Group recognize it as separate from M. temminckii.
Unlike the family Chelydridae as a whole, the genus Macrochelys is exclusively North American. Hutchison considered the genus Chelydrops to be a junior synonym of Macrochelys, and recombined its type species, Chelydrops stricta from the Miocene of Nebraska, as the fourth species of Macrochelys.
There are two other species known only from fossil remains:
  • †Macrochelys auffenbergi Dobie, 1968
  • †''Macrochelys schmidti''