LOCOMOTION
Archelon swam using its paddle-like flippers.

WHEN ARCHELON LIVED
Archelon lived during the late Cretaceous period.

DISCOVERY OF FOSSILS
Archelon lived in the seas in what is now North America; fossils have been found in Kansas and South Dakota, USA.

CLASSIFICATION
Archelon belonged to the Class Reptilia (reptiles), Order Chelonia (turtles, tortoises and terrapins), Suborder Cryptodira, Family Protostegidae (sea turtles from the late Cretaceous period with flippers and minimal shells), Genus Archelon.

ANCESTRY
The earliest turtles belonged to the family Proganochelyidae, primitive tortoises that lived during the Triassic period, evolving about 215 million years ago.

Archelon, other turtles (chelonians), and reptiles may have descended from captorhinids, primitive anapsids that lived during the Early Carboniferous period, about 340 million years ago and went extinct at the end of the Triassic period, about 250 million years ago. Captorhinids They had four sprawling legs and a long tail and evolved from amphibians.