Sphenodontia
Encyclopedia
Sphenodontia is an order of lizard-like
reptiles that includes only one living genus, the tuatara
(Sphenodon), and only two living species. Despite its current lack of diversity, the Sphenodontia at one time included a wide array of genera in several families, and represents a lineage stretching back to the Mesozoic
Era.
Sphenodontia, once a wastebin taxon containing a diverse array of unrelated reptiles (notably the rhynchosaur
s), today consists of three families: the possibly paraphyletic Gephyrosauridae, the Pleurosauridae, and the Sphenodontidae. Sphenodontidae is the family which contains all modern tuatara, as well as a number of extinct subfamilies.
of Sphenodontia after Wu (1994), Evans et al. (2001), and Apesteguia & Novas (2003).
Lepidosauria
The Lepidosauria are reptiles with overlapping scales. This subclass includes Squamata and Sphenodontidae. It is a monophyletic group and therefore contains all descendents of a common ancestor. The squamata includes snakes, lizards, tuataras, and amphisbaenia. Lepidosauria is the sister taxon...
reptiles that includes only one living genus, the tuatara
Tuatara
The tuatara is a reptile endemic to New Zealand which, though it resembles most lizards, is actually part of a distinct lineage, order Sphenodontia. The two species of tuatara are the only surviving members of its order, which flourished around 200 million years ago. Their most recent common...
(Sphenodon), and only two living species. Despite its current lack of diversity, the Sphenodontia at one time included a wide array of genera in several families, and represents a lineage stretching back to the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
Era.
Systematics
Rhynchosaur
Rhynchosaurs were a group of Triassic diapsid reptiles related to the archosaurs.-Description:Rhynchosaurs were herbivores, and at times abundant , with stocky bodies and a powerful beak...
s), today consists of three families: the possibly paraphyletic Gephyrosauridae, the Pleurosauridae, and the Sphenodontidae. Sphenodontidae is the family which contains all modern tuatara, as well as a number of extinct subfamilies.
Taxonomy
Classification follows Wu (1994), Evans et al. (2001), and Apesteguia & Novas (2003).- Order RHYNCHOCEPHALIA / SPHENODONTIA
- Family GephyrosauridaeGephyrosauridaeGephyrosauridae was a family of sphenodonts that lived in the Late Triassic and Early Jurassic. The members of Gephyrosauridae were named lepidosaurs in 1985 by Michael Benton....
†- GephyrosaurusGephyrosaurusGephyrosaurus is an early member of Lepidosauria and the less inclusive grouping Rhynchocephalia...
† - DiphydontosaurusDiphydontosaurusDiphydontosaurus was a sphenodontian reptile from the Late Triassic of England . This small animal was related to the living tuatara, which survives on the island of New Zealand. Diphydontosaurus may have hunted and eaten insects in the crevices of ancient caves. It may have grown to a length of 4...
†
- Gephyrosaurus
- Family PleurosauridaePleurosauridaePleurosauridae is a family of extinct marine diapsid reptiles belonging to the Order Sphenodontia.Fossils from this family have been discovered in Bavaria, Germany from the Toarcian and Tithonian ....
†- PalaeopleurosaurusPalaeopleurosaurusPalaeopleurosaurus is an extinct genus of diapsid reptile belonging to the Order Sphenodontia.Palaeoleurosaurus fossils were discovered in Bavaria, Germany from Toarcian deposits. It is one of the few known aquatic sphenodontians....
† - PleurosaurusPleurosaurusPleurosaurus is an extinct genus of diapsid reptile belonging to the order Sphenodontia, and therefore related to the modern tuatara. Pleurosaurus fossils were discovered in the Solnhofen limestone formation of Bavaria, Germany....
†
- Palaeopleurosaurus
- Family Sphenodontidae
- GodavarisaurusGodavarisaurusGodavarisaurus was a sphenodontid reptile from the Early Jurassic Kota Formation of Andhra Pradesh, India....
† - Kaikaifilusaurus †
- Kawasphenodon †
- Lamarquesaurus †
- LeptosaurusLeptosaurusLeptosaurus was a Sphenodontid from the Mesozoic Era.-Classification:Leptosaurus was named a member of the Sphenodontidae family by Renesto and Viohl in 1997....
† - Pelecymela †
- SigmalaSigmalaSigmala was a reptile from the Late Triassic.-Family:Sigmala was named a sphenodont by R.L. Carroll in 1988....
† - Sphenovipera †
- TheretairusTheretairusTheretairus is a Late Jurassic genus of sphenodont reptile from the Morrison Formation of western North America, present in stratigraphic zones 5 and 6.-See also:* Prehistoric reptile* Paleobiota of the Morrison Formation...
† - Tingitana †
- RebbanosaurusRebbanosaurusRebbanosaurus is a genus of sphenodontid reptile that lived during the Early Jurassic in what is now India. It was described by Evans, 2001.-External links:*...
† - Paleollanosaurus †
- PlanocephalosaurusPlanocephalosaurusPlanocephalosaurus is an extinct genus of diapsid reptile belonging to the Order Sphenodontia.Planocephalosaurus was one of the first sphenodonts and bore a strong resemblance to the extant tuatara, albeit much smaller, at only in length. The main difference was that Planocephalosauruss teeth were...
† - Polysphenodon †
- BrachyrhinodonBrachyrhinodonBrachyrhinodon is an extinct genus of sphenodontian from the Triassic of Scotland .-Sources:* Vertebrate Palaeontology by Michael J. Benton* In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods by Nicholas C. Fraser and Hans-Dieter Sues...
† - Whitakersaurus †
- ClevosaurusClevosaurusClevosaurus is an extinct genus of sphenodontian reptile from the Triassic and the Jurassic periods of Nova Scotia, Great Britain, and Yunnan...
† - Subfamily Sphenodontinae
- Homoeosaurus †
- SapheosaurusSapheosaurusSapheosaurus was a sphenodontid of the suborder Homoeosauria, although its skull was longer and narrower than that of Homoeosaurus. It was classified as a genus of sapheosaurid by Michael Benton in 1985.-Species:...
† - Ankylosphenodon †
- PamizinsaurusPamizinsaurusPamizinisaurus is a genus of sphenodontian reptile known from Lower Cretaceous Tlayúa Formation of Mexico. A crushed skeleon of a juvenile reptile was found in Tlayua Quarry, in central Mexico. It was named Pamizinsaurus tlayuaensis by Reynoso in 1997, after the name of the quarry of which it...
† - ZapatadonZapatadonZapatadon was a sphenodontid reptile from the end of the Early Jurassic La Boca Formation of Tamaulipas, Mexico.-Classification:Zapatadon was closely related to Cynosphenodon, Homoeosaurus, Sapheosaurus, Ankylosphenodon, Pamazinsaurus, and the modern Tuatara....
† - Tribe Sphenodontini
- CynosphenodonCynosphenodonCynosphenodon is an extinct genus of the family Sphenodontidae from the Middle Jurassic La Boca Formation of Tamaulipas, Mexico. Growth patterns in the teeth of Cynosphenodon suggest its close relationship with the modern tuatara....
† - Sphenodon (tuataraTuataraThe tuatara is a reptile endemic to New Zealand which, though it resembles most lizards, is actually part of a distinct lineage, order Sphenodontia. The two species of tuatara are the only surviving members of its order, which flourished around 200 million years ago. Their most recent common...
)
- Cynosphenodon
- (unranked) Opisthodontia †
- OpisthiasOpisthiasOpisthias is a Late Jurassic genus of sphenodont reptile from the Morrison Formation of western North America, present in stratigraphic zones 2 and 4-6.-See also:* Prehistoric reptile* Paleobiota of the Morrison Formation...
† - Tribe Eilenodontini †
- ToxolophosaurusToxolophosaurusToxolophosaurus was a Sphenodontid from the Early Cretaceous–age Kootenai Formation of Montana.-Discovery:Toxolophosaurus cloudi was found by Olson in 1960 in the Kootenai Formation, 223.75 feet above the base of the Kootenai.-Classification:...
† - Priosphenodon †
- EilenodonEilenodonEilenodon is a Late Jurassic genus of sphenodont reptile from the Morrison Formation of western North America, present in stratigraphic zone 4.-See also:* Prehistoric reptile* Paleobiota of the Morrison Formation...
†
- Toxolophosaurus
- Opisthias
- Godavarisaurus
- Family Gephyrosauridae
Phylogeny
The following is a cladogramCladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
of Sphenodontia after Wu (1994), Evans et al. (2001), and Apesteguia & Novas (2003).