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Amniotes are distinguished from the other living tetrapod clade — the non-amniote lissamphibians (frogs/toads, salamanders/newts and caecilians) — by the development of three extraembryonic membranes (amnion for embryonic protection, chorion for gas exchange, and allantois for metabolic waste disposal or storage), thicker and keratinized ...
The three modern orders are Anura (the frogs), Caudata (or Urodela, the salamanders), and Gymnophiona (or Apoda, the caecilians). [15] It has been suggested that salamanders arose separately from a temnospondyl-like ancestor, and even that caecilians are the sister group of the advanced reptiliomorph amphibians, and thus of amniotes. [16]
The most recent order of reptiles, squamates, [32] are recognized by having a movable quadrate bone (giving them upper-jaw movement), possessing horny scales and hemipenes. They originate from the early Jurassic and are made up of the three suborders Lacertilia (paraphyletic), Serpentes, and Amphisbaenia. Although they are the most recent order ...
The Lissamphibia (from Greek λισσός (lissós, "smooth") + ἀμφίβια (amphíbia), meaning "smooth amphibians") is a group of tetrapods that includes all modern amphibians. Lissamphibians consist of three living groups: the Salientia (frogs and their extinct relatives), the Caudata (salamanders and their extinct relatives), and the ...
Of the three orders of amphibians, Anura (frogs and toads) and Urodela (salamanders) have representative species with webbed feet. Frogs that live in aquatic environments, like the common frog (Rana temporaria), have webbed feet. Salamanders in arboreal and cave environments also have webbed feet, but in most species, this morphological change ...
Tetrapoda includes three living classes: amphibians, reptiles, and mammals. Overall, the biodiversity of lissamphibians , [ 23 ] as well as of tetrapods generally, [ 24 ] has grown exponentially over time; the more than 30,000 species living today are descended from a single amphibian group in the Early to Middle Devonian.
Snakes move faster on small branches and when contact points are present, in contrast to limbed animals, which do better on large branches with little 'clutter'. [ 118 ] Gliding snakes ( Chrysopelea ) of Southeast Asia launch themselves from branch tips, spreading their ribs and laterally undulating as they glide between trees.
Of the tailless amphibians (the frogs and toads of the sub-class Anura) the majority are aquatic to an insignificant extent in adult life, but in that considerable minority that are mainly aquatic we encounter for the first time the problem of adapting the tailless-tetrapod structure for aquatic propulsion. The mode that they use is unrelated ...