सरडा

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सरडे (इंग्लिश: Lizard , लिझर्ड;) हा सुमारे ३८०० प्रजाती असलेला खवले असलेल्या सरिसृपांचा एक मोठा गट आहे. अंटार्क्टिका व काही द्वीपसमूह वगळता पॄथ्वीवर अन्य सर्व खंडांमध्ये विविध प्रजातींचे सरडे आढळतात. प्राणिशास्त्रीय दृष्ट्या सरड्यांना लॅसर्टिलिया गोत्र मानले जाते. या गोत्रात साप वगळता लेपिडोसॉरिया प्रगोत्राचे सर्व प्राणी समाविष्ट होतात. सरडा विविध रंगांमध्ये आढळतो.
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Lizards are a widespread group of squamate reptiles, with approximately 6,000 species,[1] ranging across all continents except Antarctica, as well as most oceanic island chains. The group, traditionally recognized as the suborder Lacertilia, is defined as all extant members of the Lepidosauria (reptiles with overlapping scales) that are neither sphenodonts (i.e., tuatara) nor snakes – they form an evolutionary grade.[2] While the snakes are recognized as falling phylogenetically within the Toxicofera clade from which they evolved, the sphenodonts are the sister group to the squamates, the larger monophyletic group, which includes both the lizards and the snakes.
Lizards typically have feet and external ears, while snakes lack both of these characteristics. However, because they are defined negatively as excluding snakes, lizards have no unique distinguishing characteristic as a group. Lizards and snakes share a movable quadrate bone, distinguishing them from the sphenodonts, which have more primitive and solid diapsid skulls. Many lizards can detach their tails to escape from predators, an act called autotomy. Vision, including color vision, is particularly well developed in most lizards, and most communicate with body language or bright colors on their bodies, as well as with pheromones. Lizards are the most speciose among extant reptiles, comprising about 60% of all living species.
The adult length of species within the suborder ranges from a few centimeters for chameleons such as Brookesia micra and geckos such as Sphaerodactylus ariasae to nearly 3 m (9.8 ft) in the case of the largest living varanid lizard, the Komodo dragon. Some extinct varanids reached great size. The extinct aquatic mosasaurs reached 17 m (56 ft), and the giant monitor Megalania is estimated to have reached perhaps 7 m (23 ft).
The name Sauria was coined by James Macartney (1802); it was the Latinisation of the French name Sauriens, coined by Alexandre Brongniart (1800) for an order of reptiles in the classification proposed by the author, containing lizards and crocodilians, later discovered not to be each other's closest relatives. Later authors used the term "Sauria" in a more restricted sense, i.e. as a synonym of Lacertilia, a suborder of Squamata that includes all lizards but excludes snakes. This classification is rarely used today because Sauria so-defined is a paraphyletic group. It was defined as a clade by Jacques Gauthier, Arnold G. Kluge and Timothy Rowe (1988) as the group containing the most recent common ancestor of archosaurs and lepidosaurs (the groups containing crocodiles and lizards, as per Mcartney's original definition) and all its descendants. A different definition was formulated by Michael deBraga and Olivier Rieppel (1997) who defined Sauria as the clade containing the most recent common ancestor of Choristodera, Archosauromorpha and Lepidosauromorpha and all their descendants. However, neither of these uses have not gained wide acceptance among researchers specializing in lizards.
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