Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to Leptocleididae.

Several species survived into the final stage of the Cretaceous, the early Maastrichtian around 72 million years ago.

[4] With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetic studies indicate that they share many common features with the Leptocleididae and Elasmosauridae.

They have been found worldwide, with specimens reported from New Zealand, Australia, Japan, Morocco, the US, Canada, Eastern Europe, and South America.

[6] Plesiosaurus Tricleidus Edgarosaurus Thililua UMUT MV 19965 (from Japan) Pahasapasaurus (=AMM 98.1.1)[7] Palmulasaurus Dolichorhynchops Trinacromerum Eopolycotylus Polycotylus Cladogram after Ketchum and Benson (2010).