Pygopodidae, commonly known as

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 ...

, snake-lizards, or flap-footed lizards, is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

squamates Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, i ...

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 throughout the world. They range from . Geckos ar ...

. At least 35

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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 subfamily botanical names with "-oideae", and zoologi ...

and eight

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

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

snake Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...

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 Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

. 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 Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey anim ...

, 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 that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores were ...

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 Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

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 The peace delma (''Delma pax'') is a species of lizard in the Pygopodidae family endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zon ...

'' can respond to a 60-decibel sound with a frequency of 11,100 Hz, more than an

octave In music, an octave ( la, octavus: eighth) or perfect octave (sometimes called the diapason) is the interval between one musical pitch and another with double its frequency. The octave relationship is a natural phenomenon that has been refer ...

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 throughout the world. They range from . Geckos ar ...

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

Carphodactylidae The Carphodactylidae, informally known as the southern padless geckos, are a family of geckos, lizards in the infraorder Gekkota. The family consists of 32 described species in 7 genera, all of which are endemic to Australia. They belong to the s ...

and

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

Classification

FAMILY PYGOPODIDAE * Subfamily Lialisinae ** Tribe Lialisini *** Genus ''

Lialis ''Lialis'' is a genus of legless lizards in the family Pygopodidae. The genus is native to Australia and New Guinea. Diet Lizards in the genus ''Lialis'' specialize in eating skinks.Patchell F, Shine R (1986). "Feeding Mechanisms in Pygopodid L ...

'' (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 australi ...

'' (21 species) ** Genus ''

Paradelma ''Paradelma orientalis'', commonly known as the Brigalow scaly-foot or Queensland snake-lizard, is a species of legless lizard in the family Pygopodidae. It is endemic to Australia and is the only species in the monotypic genus ''Paradelma''. Co ...

'' (

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 "unispec ...

) ** Genus ''

Pygopus ''Pygopus'' is a genus belonging to the 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 recognized as being valid ...

'' (five species) ** Tribe Aprasiaini *** Subtribe Aprasiaina **** Genus ''

Ophidiocephalus The bronzeback snake-lizard (''Ophidiocephalus taeniatus'') is a species of lizards in the family Pygopodidae endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, ...

'' (monotypic) **** Genus ''

Aprasia ''Aprasia'' is a genus of lizards in the family Pygopodidae. The genus is endemic to Australia. The species in the genus ''Aprasia'' are worm-like, burrowing lizards. At least four of the species are oviparous. Species The genus ''Aprasia'' cont ...

'' (13 species) *** Subtribe Pletholaxina **** Genus '' Pletholax'' (2 species)

Shared gecko characteristics

Differences from snakes

Hearing

Taxonomy

Classification

See also

References

Further reading