Heliobatis was a small stingray that lived during the Eocene epoch, around 50 million years ago. Its fossils are famous from the Green River Formation in Wyoming, USA, where entire rays have been preserved in exquisite detail, complete with their soft bodies and long, whip-like tails. Heliobatis had a flattened, diamond-shaped body and glided gracefully along the muddy bottoms of ancient lakes, rippling its wide fins to stir up the sediment. It fed on small crustaceans, worms, and other bottom-dwelling creatures, crushing them with its flattened teeth. Unlike many of its relatives, Heliobatis lacked a venomous spine on its tail, making it a gentle and harmless swimmer. Its remarkable preservation has made it a favorite of fossil collectors and a window into the warm, shallow waters that once covered the American West.
