Legless lizard may refer to any of several groups of
lizards that have independently lost limbs or reduced them to the point of being of no use in locomotion.[1] It is the common name for the family
Pygopodidae.[2] These lizards are often distinguishable from
snakes on the basis of one or more of the following characteristics: possessing eyelids, possessing external ear openings, lack of broad belly scales, notched rather than forked tongue, having two more-or-less-equal
lungs, and/or having a very long tail (while snakes have a long body and short tail).[1]
Many
families of lizards have independently evolved
limblessness or greatly reduced limbs (which are presumably non-functional in locomotion), including the following examples:[1]
Anguinae – An entirely legless subfamily native to Europe, Asia, North America and North Africa, contains well-known species such as
slow worms, glass snakes/lizards and the
scheltopusik.
Cordylidae – an African family of 66 species, with one virtually legless genus Chamaesaura, containing five species with hindlimbs reduced to small scaly protuberances.
Pygopodidae – all 44 species; they belong to the genera Aprasia, Delma, Lialis, Ophidiocephalus, Paradelma, Pletholax and Pygopus. All are endemic to Australia, except the two species of Lialis, which also occur in
New Guinea, one of which is endemic to that island. Pygopodids are not strictly legless since, although they lack forelimbs, they possess hindlimbs that are greatly reduced to small digitless flaps, hence the often used common names of "flap-footed lizards" or "scaly-foot".[2] The pygopodids are considered an advanced evolutionary
clade of the
Gekkota, which also contains six families of
geckos.
Dibamidae – all 23 species in the family, which comprises the
monotypic Mexican genus Anelytropsis and the Southeast Asian genus Dibamus. All are limbless burrowers that are nearly or completely blind.
Ophiodes a genus of legless lizard native to South America, nested within the otherwise legged
galliwasps.
Gymnophthalmidae – a large
neotropical family containing many species with reduced limbs, the most extreme being the 23 species in the genus Bachia, which escape by making sudden
saltatory "figure-8" flicks with the body and tail.