Prehistoric Models: Plesiosaurs
Plesiosaurs meaning “near to lizard”, are a group of marine reptiles that first appear in the fossil record during the end of the Triassic Period and go extinct with the dinosaurs at the end of the Cretaceous period. Pliosaurs are a subgroup of plesiosaurs with some of the largest predatory jaws in the history of life on Earth! To see my plesiosaur fossils click here.
Kingdom: Animalia – Phylum: Chordata – Superclass: Tetrapoda – Class: Reptilia – Clade: Diapsida – Superorder: Sauropterygia – Order: Plesiosauria – Clade: Neoplesiosauria – Superfamily: Plesiosauroidea
(plesiosaurs)
Late Triassic to Late Cretaceous

Genus: Plesiosaurus ”Almost lizard”
Pronounced: Pleh-see-oh-sore-us
Named By: William Conybeare & Henry De la Beche - 1821
Species: P. dolichodeirus (type)
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Superfamily: Plesiosauroidea – Family: Plesiosauridae
Size: 3.5 meters long
Known locations: England; Lias Group
Time period: Jurassic (Sinemurian)
Diet: Piscivore

Genus: Attenborosaurus ”Attenborough’s lizard”
Pronounced: At-ten-bo-ro-sore-us
Named By: Robert T. Bakker - 1993
Species: A. conybeari (type)
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Superfamily: Plesiosauroidea – Family: Plesiosauridae
Size: 5 meters long
Known locations: England; Dorset
Time period: Early Jurassic
Diet: Piscivore

Genus: Hydrotherosaurus ”Water beast lizard”
Pronounced: Hy-dro-fee-roe-sore-us
Named By: Samuel Paul Welles - 1943
Species: H. alexandrae (type)
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Superfamily: Plesiosauroidea – Family: Elasmosauridae
Size: 8 meters long
Known locations: USA - California - Moreno Formation
Time period: Cretaceous (Maastrichtian)
Diet: Piscivore

Genus: Elasmosaurus ”Thin plate lizard”
Pronounced: El-lazz-mo-sore-us
Named By: Edward Drinker Cope - 1868
Species: E. platyurus (type)
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Family: Elasmosauridae
Size: 13-14 meters long
Known locations: England; Kimmeridge Clay Formation, and Norway; Svalbard, Spitsbergen
Time period: Cretaceous (Campanian)
Diet: Piscivore

Genus: Elasmosaurus ”Thin plate lizard”
Pronounced: El-lazz-mo-sore-us
Named By: Edward Drinker Cope - 1868
Species: E. platyurus (type)
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Family: Elasmosauridae
Size: 13-14 meters long
Known locations: England; Kimmeridge Clay Formation, and Norway; Svalbard, Spitsbergen
Time period: Cretaceous (Campanian)
Diet: Piscivore

Genus: Thalassomedon ”Sea lord”
Pronounced: Fal-las-so-me-don
Named By: Samuel Paul Welles - 1943
Species: T. hanningtoni (type)
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Superfamily: Plesiosauroidea – Family: Elasmosauridae
Size: 12 meters long
Known locations: USA, Colorado – Graneros Shale Formation, and Montana – Belle Fourche Formation
Time period: Cretaceous (Cenomanian)
Diet: Piscivore

Genus: Dolichorhynchops “Long-nosed eye”
Pronounced: Dol-lee-kor-rin-chops
Named By: Samuel Wendell Williston - 1902
Species: D. osborni (type), D. herschelensis, D. tropicensis
Classification: Sperorder: Sauropterygia – Order: Plesiosauria – Suborder: Plesiosauroidea – Family: Polycotylidae
Size: 3 meters long
Known locations: Canada, Saskatchewan; Bearpaw Formation. USA, Kansas; Smokey Hill Chalk & Fort Hays Limestone, Utah - Tropic Shale
Time period: Cretaceous (Turonian to Campanian)
Diet: Carnivore
Kingdom: Animalia – Phylum: Chordata – Superclass: Tetrapoda – Class: Reptilia – Clade: Diapsida – Superorder: Sauropterygia – Order: Plesiosauria – Clade: Neoplesiosauria – Suborder: Pliosauroidea
(pliosaurs)
Late Triassic to Late Cretaceous

Genus: Liopleurodon “Smooth sided teeth”
Pronounced: Lie-oh-ploor-oh-don
Named By: Henri-Émile Sauvage – 1873
Species: L. ferox (type), L. pachydeirus
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Suborder: Pliosauroidea – Family: Pliosauridae
Size: 6.39 meters long
Known locations: England, France and Germany
Time period: Late Jurassic (Callovian to Tithonian)
Diet: Carnivore

Genus: Pliosaurus ”More lizard”
Pronounced: Ply-oh-sore-us.
Named By: Richard Owen - 1841
Species: P. brachydeirus (type), P. almanzaensis, P. brachyspondylus, P. carpenteri, P. funkei, P. kevani, P. macromerus, P. patagonicus, P. portentificus, P. rossicus, P. westburyensis.
Classification: Superorder: Sauropterygia – Order: Plesiosauria – Suborder: Pliosauroidea – Family: Pliosauridae
Size: Some species up to 10 meters long, with skulls approximately 2 meters long
Known locations: England; Kimmeridge Clay Formation, and Norway; Svalbard, Spitsbergen
Time period: Late Jurassic (Kimmeridgian to Tithonian)
Diet: Carnivore
