Sphenodontia

Definition

Sphenodontia is an order of reptiles that includes only one living genus, the tuatara. These reptiles are distinct from lizards and have unique anatomical features.

5 Must Know Facts For Your Next Test

1. Sphenodontia is represented by a single living genus: Sphenodon, commonly known as the tuatara.
2. Tuatara are native to New Zealand and have been isolated there for millions of years.
3. Unlike lizards, tuatara possess a third 'parietal' eye on top of their heads, which is believed to help regulate circadian rhythms.
4. Tuatara have a slow metabolism and can live over 100 years.
5. Their skull structure is more primitive compared to other modern reptiles, resembling early diapsid reptiles.

Review Questions

• What is the only living genus in the order Sphenodontia?
• Where are tuatara naturally found?
• What unique feature distinguishes tuatara from lizards?

Related terms

Squamata: The largest order of reptiles that includes lizards and snakes.

Diapsid: A group of amniote tetrapods that developed two holes (temporal fenestra) in each side of their skulls.

Rhynchocephalia: The broader clade that includes all extinct relatives as well as the modern Sphenodontia.