Cynosphenodon

Cynosphenodon
Temporal range:
Diagram of preserved skull elements
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Rhynchocephalia
Family: Sphenodontidae
Genus: Cynosphenodon
Reynoso, 1996
Type species
Cynosphenodon huizachalensis
Reynoso, 1996

Cynosphenodon (/ˌsnəˈsfɛnədɒn/ SY-nə-SFEN-ə-don; "Dog Sphenodontian") is an extinct genus of rhynchocephalian in the family Sphenodontidae from the Middle Jurassic La Boca Formation of Tamaulipas, Mexico. It is known from a largely complete lower jaw and fragments of the upper jaw. It is suggested to be among the closest known relatives of the tuatara, with both being placed in the Sphenodontinae, which is supported by among other characters, the growth pattern of the teeth.

Cladogram after Simoes et al. 2022.

Sphenodontia