[[Berkas:Dolichorhynchops Vienna.jpg|thumb|Spesimen di Wina]]
DibawahDi bawah ini adalah kladogram kekerabatan Polycotylidae dari Ketchum & Benson, 2011.<ref name=Marmornectes>{{cite journal |author=Hilary F. Ketchum |author2=Roger B. J. Benson |name-list-style=amp |year=2011 |title=A new pliosaurid (Sauropterygia, Plesiosauria) from the Oxford Clay Formation (Middle Jurassic, Callovian) of England: evidence for a gracile, longirostrine grade of Early-Middle Jurassic pliosaurids |journal=Special Papers in Palaeontology |volume=86 |pages=109–129 |url=https://www.palass.org/publications/special-papers-palaeontology/archive/86/article_pp109-129}}</ref>
