Named By: Andrews - 1909.
Classification: Chordata, Reptilia, Sauropterygia, Plesiosauria, Plesiosauroidea, Cryptoclididae.
Species: T. seeleyi (type).
Known locations: England and Svalbard.
Time period: Mid Jurassic.
Fossil representation: Skull and partial post cranial remains.
Tricleidus is but one of many cryptoclidid plesiosaurs active in European waters during the Jurassic, although it is not as well-known as the type genus of this group, Cryptoclidus. The type species name T. seeleyi is in honour of the British palaeontologist Harry Govier Seeley. Another species based upon American fossils once attributed to the genus as Tricleidus laramiensis (renamed from Cimoliasaurus laramiensis) is now known as the genus Tatenectes.