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Concept
Lepidosauria
Résumé
The Lepidosauria (,lEpᵻdou'sɔːri@, from Greek meaning scaled lizards) is a subclass or superorder of reptiles, containing the orders Squamata and Rhynchocephalia. Squamata includes snakes, lizards, and amphisbaenians. Squamata contains over 9,000 species, making it by far the most species-rich and diverse order of non-avian reptiles in the present day. Rhynchocephalia was a formerly widespread and diverse group of reptiles in the Mesozoic Era. However, it is represented by only one living species: the tuatara (Sphenodon punctatus), a superficially lizard-like reptile native to New Zealand.
Lepidosauria is a monophyletic group (i.e. a clade), containing all descendants of the last common ancestor of squamates and rhynchocephalians. Lepidosaurs can be distinguished from other reptiles via several traits, such as large keratinous scales which may overlap one another. Purely in the context of modern taxa, Lepidosauria can be considered the sister taxon to Archosauria, which includes Aves (birds) and Crocodilia. Testudines (turtles) may be related to lepidosaurs or to archosaurs, but no consensus has been reached on this subject. Lepidosauria is encompassed by Lepidosauromorpha, a broader group defined as all reptiles (living or extinct) closer to lepidosaurs than to archosaurs.
Lizards were originally split into two clades: the Iguania and the Scleroglossa. Snakes and amphisbaenians belong within the clade Scleroglossa. Analysis of teeth has indicated that Iguania is made up of the sister taxa Chamaeleonidae and Agamidae. Snakes are actually a branch within the lizard group. In fact, some lizards, such as the Varanids, are more closely related to snakes than they are to other lizards. Varanids are a diverse group of lizards living from Africa, throughout south, central, and east Asia, as well as the Indo-Pacific islands and Australia.
Snakes currently have about 3,070 extant species, which are grouped into the scolecophidians and the alethinophidians. The scolecophidians comprise about 370 species and are represented by small snakes with a limited gape size.
Source officielle
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