Teiidae is a family of lizards native to the Americas, generally known as Whiptails. The group has over 230 species within ten genera.
Teiids can be distinguished from other lizards by the following characteristics: they have large rectangular scales that form distinct rows ventrally and generally small granular scales dorsally, they have head scales that are separate from the skull bones, and the teiid teeth are solid at the base and “glued” to the jaw bones. Additionally, all teiids have a forked, snake-like tongue. They all possess well-developed limbs.
Teiids are all terrestrial and diurnal, and are primarily carnivorous or insectivorous, although some will include a small amount of plant matter in their diet. They all lay eggs, with some species laying very large clutches.
Certain species of whiptail lizards (genera Cnemidophorus and Aspidoscelis) have all-female or nearly all-female populations. These lizards reproduce by parthenogenesis, and research has shown that simulated mating behavior increases fertility. For instance, one female lies on top of another, engaging in pseudocopulation. When they lay eggs, the lizard that was on bottom has larger eggs while the one on top has smaller. The lizards switchs roles each mating season. The offspring are genetic clones of the mother, sparking debate as to how these lizards evolve or adapt to the environment.