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How are tuatara related to lizards and snakes?
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tuatara
The species is the sole living member of the reptile order Rhynchocephalia.
Although tuatara resemble lizards, they are not lizards. They belong to the order Rhynchocephalia, which is a distinct lineage that diverged from the order Squamataâthe group containing lizards, snakes, and amphisbaeniansâapproximately 250 million years ago.1
While they are only distantly related, tuatara and squamates are considered sister groups and share several biological traits, including:
- A transverse cloacal opening (the vent).1
- Teeth that are attached superficially to the jawbones.1
- Fracture planes in the tail vertebrae.1
- The process of ecdysis, or periodic skin shedding.1
Despite these similarities, tuatara are distinguished from squamates by unique anatomical features, such as the presence of gastralia (abdominal ribs), enclosed temporal fossae in the skull, and a beaklike extension of the premaxillary bones.1