Polycotylids have been traditionally classified as to be pliosaurs because of their short necks and large heads, but cladistic analyses including a broader suite of anatomical characters have revealed that they may be plesiosauroids, more closely related to the long-necked elasmosaurids and cryptoclidids than to pliosaurs. They share a number of features including the elongate rostrum and short postorbital region. They had a worldwide distribution in the Cretaceous Period.
- character 1
- Brancasaurus (according to Ketchum and Benson, 2011)
- 'Woolungasaurus' = Elasmosauridae indet.
- 'Alzadasaurus' = ?
- Aprosaurus ?
- Ogmodirus ?
- Fresnosaurus ?