- Type: Lizard
- Diet: Carnivore.
- Size: Between 25 and 30 centimetres long.
- Protection status: Extinct.
- Adriosaurus was an aquatic lizard that is often described as being snake-like. This is because Adriosaurushad a thin elongated body similar to a snakes proportions, yet still retained small limbs. These limbs are widely thought to have been vestigial, which means that they were present yet no longer fulfilled a practical purpose and at the time of its discovery, Adriosaurus was taken as one of the first known transitional forms that showed lizards evolving into limbless snakes.