The Teiidae lizard family features everything from massive predators to all-female cloning colonies.

Nature · Published 3 October 2026 Swipe more like this →

In short: Native to the Americas, the Teiidae family of lizards encompasses a surprising range of forms, from the large, predatory tegus to the agile, racerunner whiptails. Beyond their diverse appearances, these reptiles possess unique biological traits, including forked tongues and, in some species, a fascinating reliance on all-female clonal reproduction.

The Teiidae family, which has existed since the Late Cretaceous, is primarily found in the tropical and subtropical regions of the New World. These lizards are characterized by the absence of osteoderms and an open supratemporal fossa. While they exhibit great variation, they are generally divided into groups such as the large terrestrial predators known as Tupinambis, semiaquatic snail-eating Dracaena, and the lacertid-like racerunners of the genus Cnemidophorus.

A defining feature of the family is the use of a flat, elongated, forked tongue in conjunction with Jacobson's organ to detect chemical cues in their environment. These lizards are typically diurnal and terrestrial, foraging actively within their preferred temperature ranges. Their physical structure includes well-developed limbs and distinct scales, with large rectangular rows ventrally and smaller granular scales dorsally. Most species are carnivorous or insectivorous, though some include plant matter in their diets.

Perhaps most intriguing is the existence of obligate parthenogenetic species within the family. In these all-female lineages, no males are known to exist, and reproduction occurs without sperm. Some of these lizards engage in pseudocopulation, a behavior where one female adopts a male-like role to stimulate fertility in another. While the exact meiotic mechanism remains a subject of ongoing research, this unisexual reproduction allows these hybrids to thrive as distinct clonal populations across the Americas.

The evolutionary history of the Teiidae is equally complex. While they are currently restricted to the Americas, fossil evidence suggests a brief, unusual colonization of Europe during the Late Eocene, potentially via trans-Atlantic rafting. Today, the family includes approximately 150 species across 18 genera. Their biological success, ranging from the massive tegus that can exceed a meter in length to the highly specialized parthenogenetic whiptails, highlights the remarkable adaptability of this lizard family.

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