Basal ichthyopterygians (prior to and ancestral to true Ichthyosauria) were mostly small (a meter or less in length) with elongate bodies and long spool shaped vertebrae, indicating that they swam in a sinuous eel-like manner. This allowed for quick movements and maneuverability that were an advantage in shallow-water hunting.[3] Even at this early stage they were already very specialised animals with proper flippers, and would have been incapable of movement on land. These animals seem to have been widely distributed around the coast of the northern half of Pangea, as they are known the Late Olenekian and Early Anisian (early part of the Triassic period) of Japan, China, Canada, and Spitsbergen (Norway). By the later part of the Middle Triassic they were extinct, having been replaced by t