5. Any of various extinct fishlike marine reptiles of the order Ichthyosauria of the Triassic Period to the Cretaceous Period, having a porpoiselike head and an elongated, toothed snout.

• 鱼龙三叠纪至白垩纪间的属于鱼龙目的水生爬行动物中的任一种，现已绝迹，该动物头象海豚，喙长，有牙收藏指正