Genus: Sphenovipera REYNOSO, 2005
Etymology: From Spheno, in allusion to sphenodontians, and Latin, vipera, " venomous snake": venonmous sphenodontians.

Species: jimmysoyi REYNOSO, 2005
Etymology: For the joy of Jim Clark (once his favorite Huizachal Canyon locality was lost forever) (pronounced he-miss-joyee).

Holotype: IGM 6076

Locality: Jim's Joy locality, Huizachal Canyon, Municipio de Ciuda Victoria, Tamaulipas State, Mexico.

Horizon: Lower part of La Boca Formaiton.

Biostratigraphy:

Age: Middle Jurassic.

Material: An almost-complete right lower jaw with teeth.

Note: 2 teeth show indications of the animal being venomous.