The delineation of natural areas in New Zealand: The distribution of New Zealand reptiles

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The Reptilia, in New Zealand, are represented by four groups: the marine turtles (Testudinates), the tuatara (Rhynchocephalia), the marine snakes (Ophidia), and the lizards (Sauria). The marine turtles and snakes being stragglers have little bearing on the subject.
The tuatara once inhabited almost the entire area, but today is more or less restricted to sixteen islands.
The lizards are represented by the Gekkonidae and the Scincidae. The endemic gekkonids are peculiar in that they are the only viviparous species known; Gehyra oceanica, a comparatively recent introduction to the fauna, is egg-laying.
The habits of some geckos and skinks, including their ability to withstand long periods of fast, are conducive to accidental transportation in cargo or on oceanic drift. The viviparity of the gekkonids suggests a long period of isolation which would be necessary for their evolution to have advanced so far.