Their beaks and spiky shells look prehistoric, but they live in the modem world, and new research into the largest freshwater turtles in the Northern Hemisphere reveals a surprise find about the creatures.

The alligator snapping turtle, sometimes referred to as the "dinosaur of the turtle world," has long believed to be one species, but new research reveals two new species of the reptile, bringing the known total to three.

Researchers from University of Florida report that the limited distribution of the new species may require a re-examination of conservation along the coastal rivers along the northern Gulf of Mexico that the snapping turtles inhabit.

Writing in the journal Zootaxa, the researchers present a revised classification of the genus Macrochelys to include Macrochelys temminkii and the two new species, Macrochelys apalachicolae and Macrochelys suwanniensis. The two new species are named after the river systems they are found in.

"We have to be especially careful with our management of the Suwannee River species because this turtle exists only in that river and its tributaries," said lead study author Travis Thomas, a Florida Fish and Wildlife Commission scientist. "If something catastrophic were to occur, such as a chemical spill or something that affects the entire river, it could potentially devastate this species. The turtle is extremely limited by its habitat. All it has is this river and it has nowhere else to go."

Geographic divisions led to genetic differences between the alligator snapping turtle species, the researchers said.

"M. temminkii is found in river drainages such as the Mississippi and Mobile, while M. apalachicolae is confined to the Apalachicola and other Panhandle rivers," said study co-author Kenneth Krysko, a herpetologist with the Florida Museum on the UF campus.

Krysko said there are no alligator snapping turtles in the seven rivers that geographically separate the Suwannee and Ochlockonee rivers.

"This gap creates a geographic isolation that has likely resulted in the Suwannee species being the most genetically and morphologically distinct of the three Macrochelys lineages," he said.