What is the lifecycle of the tuatara?

Tuatara are very primitive lizards which can grow up to 2 feet or a bit longer. They live on small animals and insects. They mature sexually in about twenty years and the females lay eggs every 4 years. They are thought to have a lifespan of about 50 - 60 years in the wild. One example, in captivity in In Invercargill, NZ is known to be over a 110 years old.