Abstract: A new diapsid reptile is named and described on the basis of a well—preserved skeleton from the Late Jurassic / Early Cretaceous Yixian Formation, Liaoning Province, northeastern China. The specimen represents an unusually long—necked diapsid, which shows specialized adaptations to an aquatic life style in a lacustrine environment. Morphological characters, such as the small skull with a pointed snout, needle—like teeth, and a long neck, strongly indicate a piscivorous diet of the animal. This discovery documents the. first known long—necked reptile from the Mesozoic lake deposits of northeastern China.