an order of reptiles containing the lizards and snakes, which have a skin with horny epidermal scales or shields. The moveable quadrate bone makes it possible to move the upper jaw with respect to the braincase.
It is widely assumed that there is a functional relationship in squamates between flicking of the tongue and delivery of chemical cues to the vomeronasal system (VNS; see Young, 1993), Electrophysiological data have demonstrated a close temporal correlation between the activity pattern of the tongue retractor system and stimulation of the sensory receptors in the vomeronasal organs (VNO; Meredith & Burghardt, 1978).
Typical n ode-based definitions, then, might read as follows: "Lepidosauria is the most recent common ancestor of Sphenodon and squamates and all of its descendants" or "Mammalia is the most recent common ancestor of montremes and therians and all of their descendants."
It remains to be seen how mortality risk is distributed in natural populations of squamates, but the effect still calls the generality of the Shine and Schwarzkopf (1992) model into serious question (Niewiarowski and Dunham 1994).