Fossil Stingray

Heliobatis radians is one of two species of extinct freshwater stingray found in the Green River Formation's Fossil Lake, along with the more primitive Asterotrygon maloneyi. A rare species of fish, only slightly more than 1,000 examples of Heliobatis have been excavated. Named by famous Yale paleontologist O.C. Marsh in 1877, the Heliobatis holotype that Marsh recovered can now be found at Yale's Peabody Museum of Natural History.

Heliobatis is characterized by barbed "stings" at the end of a long, whip-like tail that can comprise up to half its total body length. As a bottom feeder, its teeth were adapted to prey on benthic creatures including mollusks, crayfish, and shrimp. The lack of claspers on the current specimen indicates that this was a female stingray.

Approximately 50 million years ago, Heliobatis thrived in the Green River Formation, an area that comprised more than 25,000 square miles (65,000 sq. km) of interconnected subtropical lakes spread across the current states of Wyoming, Utah, and Colorado. Today, the Green River Formation's Fossil Lake boasts some of the most abundant and well-preserved freshwater fossils anywhere in the world.