Protorothyrididae is an extinct family of small, lizard-like reptiles belonging to Eureptilia. Their skulls did not have fenestrae, like the more derived diapsids. Protorothyridids lived from the Late Carboniferous to Early Permian periods, in what is now North America. Many genera of primitive reptiles were thought to be protorothyridids. '' Brouffia'', '' Coelostegus'', '' Paleothyris'' and '' Hylonomus'', for example, were found to be more basal eureptiles in Muller and Reisz (2006), making the family as historically defined paraphyletic, though three genera, ''

Protorothyris ''Protorothyris'' is an extinct genus of Early Permian protorothyridid known from Texas and West Virginia of the United States. It was first named by Llewellyn Ivor Price in 1937 and the type species is ''Protorothyris archeri''. ''P. archeri'' ...

, Anthracodromeus,'' and '' Cephalerpeton'', were recovered as a monophyletic group. ''Anthracodromeus'', ''Paleothyris'', and ''Protorothyris w''e recovered as a monophyletic group in Ford and Benson (2020) (who did not sample ''Cephalerpeton''), who recovered them as more derived than

captorhinids Captorhinidae (also known as cotylosaurs) is an extinct family of tetrapods, traditionally considered primitive reptiles, known from the late Carboniferous to the Late Permian. They had a cosmopolitan distribution across Pangea. Description Cap ...

and ''Hylonomus'', but less so than araeoscelidians. ''Anthracodromeus'' is the earliest known reptile to display adaptations to climbing. The majority of phylogenetic studies recover protorothyridids as basal members of Eureptilia; however, Simões ''et al.'' (2022) recover them as stem- amniotes instead.

References

Prehistoric reptile families Prehistoric romeriids Taxa named by Llewellyn Ivor Price {{paleo-reptile-stub