Scleroglossa is a group of

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...

s that includes

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 ...

autarchoglossa Autarchoglossa is a clade (evolutionary grouping) of squamates that includes skinks, anguimorphs, snakes, and relatives. Autarchoglossa is supported as a monophyletic grouping (i.e. a valid clade) by morphological features in living and extinct l ...

ns (

scincomorph Scincomorpha is an infraorder and clade of lizards including skinks (Scincidae) and their close relatives. These include the living families Cordylidae (girdled lizards), Gerrhosauridae (plated lizards), and Xantusiidae (night lizards), as wel ...

anguimorph The Anguimorpha is a suborder of squamates. The group was named by Fürbringer in 1900 to include all autarchoglossans closer to '' Varanus'' and ''Anguis'' than ''Scincus''. These lizards, along with iguanians and snakes, constitute the propo ...

s, and

varanoid Varanoidea is a superfamily of lizards, including the well-known family Varanidae (the monitors and goannas). Also included in the Varanoidea are the Lanthanotidae (earless monitor lizards), and the extinct Palaeovaranidae. Throughout their l ...

s), and

amphisbaenian Amphisbaenia (called amphisbaenians or worm lizards) is a group of usually legless squamates, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As ...

s. Scleroglossa is supported by

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses that use morphological features (visible anatomical features). According to most morphological analyses, Scleroglossa is the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

of the clade

Iguania Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons, agamids, and New World lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed t ...

, which includes

iguana ''Iguana'' (, ) is a genus of herbivorous lizards that are native to tropical areas of Mexico, Central America, South America, and the Caribbean. The genus was first described in 1768 by Austrian naturalist Josephus Nicolaus Laurenti in his bo ...

chameleon Chameleons or chamaeleons (family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 202 species described as of June 2015. The members of this family are best known for their distinct range of colors, bein ...

agamid Agamidae is a family of over 300 species of iguanian lizards indigenous to Africa, Asia, Australia, and a few in Southern Europe. Many species are commonly called dragons or dragon lizards. Overview Phylogenetically, they may be sister to the I ...

s, and New World lizards. Together, Scleroglossa and Iguania make up the

crown group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

Squamata, the smallest evolutionary grouping to include all living lizards and snakes. The name Scleroglossa is derived from the Greek, ''skleros'', meaning "hard" and ''glossa'', meaning "tongue". The split between Scleroglossa and Iguania can be based on features of the tongue; iguanians have a muscular tongue and use lingual prehension to capture food, whereas scleroglossans have hard tongues and use teeth-and-jaw prehension to capture food, freeing the tongue for chemosensory activity. Recent phylogenetic analyses based on molecular data (such as DNA sequences) nest iguanians deeper within Squamata along with

snakes Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joi ...

and anguimorphs. Under this phylogeny, Scleroglossa is not a valid grouping. A new clade Bifurcata (bifurcated tongue) has been proposed to include Iguania as a sister taxon to Anguimorpha.Vidal, N. and Hedges, S.B. 2005
The phylogeny of squamate reptiles (lizards, snakes, and amphisbaenians) inferred from nine nuclear protein-coding genes
C.R. Biologies 328: 1000-1008.

Notes

Many studies also recognize a clade called
Scincogekkonomorpha Scincogekkonomorpha is a clade (evolutionary grouping) of lizards that includes scleroglossans and all lizards more closely related to scleroglossans than to iguanians. These "stem" scleroglossans include extinct lizards from the Late Jurassic a ...
, which is a
stem-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which ...
defined to include all lizards more closely related to geckos and skinks than to iguanas. Scleroglossa was first established as a
node-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which ...
, defined to include Gekkota and Autarchoglossa. Therefore, Scincogekkonomorpha rather than Scleroglossa is the proper sister taxon of Iguania.

References

Tetrapod unranked clades Scincogekkonomorpha {{lizard-stub ta:மரப்பல்லி