Any of various very large extinct aquatic lizards of the genus Mosasaurus, having modified limbs that served as paddles for swimming. These lizards, thought to have been viviparous and carnivorous, may be early ancestors of the modern monitor lizard.

• 沧龙任一种沧龙属的形体很大且已绝迹的水生蜥蜴，长有退化肢，作为游泳的桨。这些蜥蜴，尽管是胎生的食肉动物，可能是现在蜥蜴的早期祖先