中龙属（学名：Mesosaurus）是一种小型水生爬行动物，生存于早二叠纪的南美洲和南非。身长可达1米。生活于淡水之中。

中龙是最早回到水中生存的爬行动物之一，身长约1公尺，牠的脚掌有蹼，身体呈流线型，长尾巴呈鳍状。因为后腿比较长，加上尾巴灵活，被推测是用来在水中推动身体往前进。中龙的身体灵活，使牠们可以轻易地做出侧向运动、向前推进，但因为粗厚的肋骨，牠们不能扭转身体。

中龙拥有小的头骨与长的颌部，鼻孔位在尖端，使得中龙可以在水面下用鼻孔呼吸，类似现代鳄鱼。中龙的最明显特征是众多且细的牙齿。每个牙齿都位在齿槽里，但过细的牙齿难以抓到猎物。所以中龙被认为用牙齿来从水中过滤浮游生物。

Mesosaurus (meaning "middle lizard") is an extinct genus of reptile from the Early Permian of southern Africa and South America. Along with the genera Brazilosaurus and Stereosternum, it is a member of the family Mesosauridae and the order Mesosauria. Mesosaurus was long thought to have been one of the first marine reptiles, although new data suggests that at least those of Uruguay inhabited a hypersaline water body, rather than a typical marine environment. In any case, it had many adaptations to a fully aquatic lifestyle. It is usually considered to have been anapsid, although Friedrich von Huene considered that it was synapsid, and this hypothesis has been revived recently.