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Contact

About the author
Email: plesiosauria@gmail.com
Follow: @adamstuartsmith

Higher taxa

  • Sauropterygia
  • Eosauropterygia
  • Eusauropterygia
  • Pachypleurosauria
  • Nothosauria
  • Pistosauroidea
  • Pistosauria
  • Plesiosauria
  • Pliosauroidea
  • Plesiosauroidea

Families

  • Aristonectidae
  • Brachauchenidae
  • Cimoliasauridae
  • Cryptoclididae
  • Elasmosauridae
  • Leptocleididae
  • Microcleididae
  • Plesiosauridae
  • Pliosauridae
  • Polycotylidae
  • Rhomaleosauridae

Genera

The genera section is under construction, active pages are indicated by an asterisk

  • A
  • Albertonectes
  • Alexeyisaurus
  • Alzadosaurus
  • Anningasaura
  • Aphrosaurus
  • * 'Apractocleidus'
  • * Archaeonectrus
  • * Aristonectes
  • * Attenborosaurus
  • Augustasaurus
  • Avalonnectes
  • B
  • Bathyspondylus
  • Bishanopliosaurus
  • * Bobosaurus
  • Borealonectes
  • Brachauchenius
  • * Brancasaurus
  • C
  • Callawayasaurus
  • 'Cimoliasaurus'
  • Colymbosaurus
  • * Cryptoclidus
  • D
  • Dolichorhynchops
  • E
  • * Edgarosaurus
  • * Elasmosaurus
  • Eoplesiosaurus
  • Eopolycotylus
  • * Eretmosaurus
  • Eromangasaurus
  • Eurycleidus
  • F
  • Fresnosaurus
  • Futabasaurus
  • G
  • Gallardosaurus
  • Georgiasaurus
  • H
  • Hauffiosaurus
  • Hydralmosaurus
  • Hydrorion
  • Hydrotherosaurus
  • I
  • J
  • K
  • * Kaiwhekea
  • * Kimmerosaurus
  • * Kronosaurus
  • L
  • * Leptocleidus
  • Leurospondylus
  • * Libonectes
  • * Liopleurodon
  • Lusonectes
  • M
  • * Macroplata
  • Manemergus
  • * Maresaurus
  • Marmornectes
  • Mauisaurus
  • Megalneusaurus
  • * Meyerasaurus
  • Microcleidus
  • Morenosaurus
  • * 'Morturneria'
  • Muraenosaurus
  • N
  • Nichollssaura
  • O
  • * Occitanosaurus
  • 'Ogmodirus'
  • Opallionectes
  • P
  • * Pachycostasaurus
  • Pahasapasaurus
  • Palmulasaurus
  • Pantosaurus
  • * Peloneustes
  • Pistosaurus
  • Plesiopleurodon
  • Plesiopterys
  • * Plesiosaurus
  • Pliosaurus
  • Polycotylus
  • Polyptychodon
  • Q
  • R
  • * Rhomaleosaurus
  • S
  • Seeleyosaurus
  • Scanisaurus
  • * Simolestes
  • Sthenarosaurus
  • Stratesaurus
  • 'Stretosaurus'
  • Strongylokrotaphus
  • Styxosaurus
  • Sulcusuchus
  • T
  • Tatenectes
  • Terminonatator
  • * Thalassiodracon
  • * Thalassomedon
  • 'Thaumatosaurus'
  • *Thililua
  • Trememesacleis'
  • *Tricleidus
  • Trinacromerum
  • Tuarangisaurus
  • U
  • Umoonasaurus
  • V
  • Vinialesaurus
  • W
  • Wapuskanectes
  • Westphaliasaurus
  • Woolungasaurus
  • X
  • Y
  • Yuzhoupliosaurus
  • Z
  • Zarafasaura

Polycotylidae

Classification

Sauropterygia--> Eosauropterygia--> Eusauropterygia--> Pistosauroidea--> Plesiosauria--> Plesiosauroidea--> cryptocleidoidea--> Polycotylidae

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

Polycotylid genera

  • Brancasaurus (according to Ketchum and Benson, 2011)
  • Dolichorhynchops
  • Edgarosaurus
  • Eopolycotylus
  • Georgiasaurus
  • Umoonasaurus
  • Pahasapasaurus
  • Palmulina
  • Polycotylus
  • Sulcusuchus
  • Thililua
  • Trinacromerum

Several elasmosaurid genera are considered nomina dubia or are regarded as junior synonyms of other genera. The following names are therefore invalid :
  • 'Woolungasaurus' = Elasmosauridae indet.
  • 'Alzadasaurus' = ?
  • Aprosaurus ?
  • Ogmodirus ?
  • Fresnosaurus ?

Popular pages

Liopleurodon

Plesiosaurus

Locomotion

Living plesiosaurs?

Crystal Palace plesiosaurs

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Further reading

Playtime

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The skeletons in the site header are (from left to right): Kronosaurus (in the Museum of Comparative Zoology, Harvard University, Cambridge), Thalassomedon (in the American Museum of Natural History, New York), Cryptoclidus (In the Hunterian Museum and Art Gallery, Glasgow), Rhomaleosaurus (in the Natural History Museum, London), Dolichorhynchops (in the Smithsonian Institution's National Museum of Natural History, Washington) and Thalassiodracon (in the Natural History Museum, London).

©2011 Copyright Adam S. Smith. This site opened in June 2001. Last updated April 2013.