| Named By: | Susan E. Evans in 1980 |
| Time Period: | Late Triassic-Early Jurassic, Rhaetian-195 |
| Location: | Wales |
| Size: | Roughly up to 20 centimetres long |
| Diet: | Insectivore |
| Fossil(s): | Several individuals |
| Classification: | | Chordata | Reptilia | Rhynchocephalia | Gephyrosauridae | |
Gephyrosaurus is a genus of early rhynchocephalian first described and named in 1980 by Susan E. Evans. They are distantly related to the extant Sphenodon (tuatara of New Zealand) with which they shared a number of skeletal features including a large tooth row along the side of the palatine bone (part of the palate) and posterior process of the dentary bone (part of the lower jaw). The type species, G. bridensis, lived during Early Jurassic in Wales, UK. Whiteside & Duffin (2017) described the second species, G. evansae, known from a partial maxilla recovered from Late Triassic (Rhaetian) fissure fills in Carboniferous Limestone in Somerset. The primitive cranial features of this organism places it within the order of Eosuchia.