Pygopodidae, commonly known as snake-lizards, or flap-footed lizards, are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

legless lizards 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.Pough ''et al.'' 1992. Herpetology: Third Edition. Pearson Prentice Hall:Pearson Education ...

with reduced or absent limbs, and are a type of

gecko Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates. They range from . Geckos are unique among lizards ...

. The 47

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

are placed in two

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zool ...

and eight

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

. They have unusually long, slender bodies, giving them a strong resemblance to

snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

s. Like snakes and most geckos, they have no eyelids, but unlike snakes, they have external ear holes and flat, unforked tongues. They are native to

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

. Pygopodids have no fore limbs at all, but they do possess

vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

hind limbs in the form of small, flattened flaps. These may have some role in courtship and defensive behaviour, and may even aid in locomotion through vegetation. Some species are

insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores we ...

burrowing animals, but others are adapted to moving through dense spinifex or other vegetation.

Shared gecko characteristics

The pygopodids and other geckos share a number of characteristics: * the production of parchment-shelled eggs in

clutch A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does th ...

sizes of two * the ability to lick clean the clear spectacles that cover their lidless eyes; * vocalization sounds like the common gecko "harsh squeak". * skull anatomy * inner ears anatomy * communal nests. Some nests have been found to have as many as 30 eggs.

Differences from snakes

Legless lizards are often killed due to their similar appearance to snakes. A number of external characteristics can be used to distinguish legless lizards (including the hooded scaly-foot) from snakes: * Flap-footed lizards have vestigial hind limbs. * Legless lizards have broad, fleshy tongues, dissimilar from the forked tongues of snakes. * Most legless lizards have external ears. * Ventral scales are in a paired series. * Unbroken tails in legless lizards are much longer than the body, whereas snake bodies are longer than their tails. * Can vocalise, snakes can not.

Hearing

Pygopodids can hear tones higher than any other reptiles. Individuals in the species '' Delma pax'' can respond to a 60-decibel sound with a frequency of 11,100 Hz, more than an

octave In music, an octave (: eighth) or perfect octave (sometimes called the diapason) is an interval between two notes, one having twice the frequency of vibration of the other. The octave relationship is a natural phenomenon that has been referr ...

above the highest note on a standard piano.

Taxonomy

Pygopodidae is one of several taxonomic families of

geckos Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates. They range from . Geckos are unique among lizards f ...

, and is most closely related to two other Australian gecko families Carphodactylidae and

Diplodactylidae The Diplodactylidae are a Family (biology), family in the suborder Gekkota (geckos), with over 150 species in 25 Genus, genera. These geckos occur in Australia, New Zealand, and New Caledonia. Diplodactylids are the most ecologically diverse and ...

Classification

FAMILY PYGOPODIDAE * Subfamily Lialisinae ** Tribe Lialisini *** Genus '' Lialis'' (two species) * Subfamily Pygopodinae ** Genus ''

Delma ''Delma'' is a genus of lizards in the family Pygopodidae. The genus ''Delma'' contains 22 valid described species, all of which are endemic to Australia. Species Recognized species of ''Delma'' according to thReptile Database *'' Delma austral ...

'' (22 species) ** Genus '' Paradelma'' (

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

) ** Genus ''

Pygopus ''Pygopus'' is a genus belonging to the Family (biology), family of Australian legless lizards (Pygopodidae). Members of this genus are also commonly called scaly-foot. Species Within the genus ''Pygopus'' the following five species are recogniz ...

'' (five species) ** Tribe Aprasiaini *** Subtribe Aprasiaina **** Genus '' Ophidiocephalus'' (monotypic) **** Genus '' Aprasia'' (14 species) *** Subtribe Pletholaxina **** Genus '' Pletholax'' (2 species)

Shared gecko characteristics

Differences from snakes

Hearing

Taxonomy

Classification

See also

References

Further reading