Polycotylidae
Polycotylids have been traditionally classified as pliosaurs because of their short necks and relatively large heads. However, cladistic analyses that take into account a broader suite of anatomical characters have revealed that they are probably plesiosauroids, and therefore more closely related to the long-necked elasmosaurids and cryptoclidids than to pliosaurs. All polycotylids share a number …