Sauropterygians, the group to which plesiosaurs belong, have the longest stratigraphic range of all Mesozoic marine reptiles. The sauropterygian fossil record spans the whole of the Triassic, Jurassic, and Cretaceous periods.

The stratigraphic ranges of the main groups of Mesozoic marine reptiles (modified from Benson et al.



Plesiosaurian clades

This nested classification for Plesiosauria shows the major clades (groups). Note that some classifications have placed Rhomaleosauridae outside of Pliosauroidea (=pliosaurs) but I have used a traditional approach here and nested Rhomaleosauridae within pliosauroids.

Sauropterygian clades

Plesiosaurs (=Plesiosauria) are derived sauropterygians.


The gallery section is divided into several categories.

Photographs gallery

This gallery contains photographs of skeletons and bones on display in museums, and photographs taken in museum collections or in the field.

Line drawings (skeletal reconstructions) gallery

This gallery contains illustrative reconstructions of bones and skeletons.


I’m in the process of creating the genus section so more plesiosaur genera will be added or updated in time.