Pachypleurosauria

The Pachypleurosauria is an exclusively Middle Triassic-aged group of semi-aquatic sauropterygians. They were once regarded as a type of ‘nothosaur’, but the traditional concept of “Nothosauria” is no longer in use because it was a paraphyletic group containing two separate evolutionary lineages. The more ‘primitive’ of the two is the Pachypleurosauria, while the more derived members form a separate clade called the “Nothosauria” under a revised definition (Rieppel 1998).

Pachypleurosaur genera include:

Anarasaurus
Dactylosaurus
Keichousaurus
Neusticosaurus (‘Pachypleurosaurus’)
‘Psilotrachelosaurus’
Serpianosaurus