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The largest living amphibian is the 1.8 m (5 ft 11 in) Chinese giant salamander (Andrias davidianus) [41] but this is a great deal smaller than the largest amphibian that ever existed—the extinct 9 m (30 ft) Prionosuchus, a crocodile-like temnospondyl dating to 270 million years ago from the middle Permian of Brazil. [42]
More generally, herpetologists work on functional problems in the ecology, evolution, physiology, behavior, taxonomy, or molecular biology of amphibians and reptiles. Amphibians or reptiles can be used as model organisms for specific questions in these fields, such as the role of frogs in the ecology of a wetland.
Frogs are used in cloning research and other branches of embryology. Although alternative pregnancy tests have been developed, biologists continue to use Xenopus as a model organism in developmental biology because their embryos are large and easy to manipulate, they are readily obtainable, and can easily be kept in the laboratory. [227]
It lists the names of frogs, salamanders and other amphibians, which scientists first described each species and what year, and the animal's known range. The American Museum of Natural History hosts Amphibian Species of the World, which is updated by herpetologist Darrel Frost. As of 2024, it contained more than 8700 species.
Genetic evidence and some anatomical details (such as pedicellate teeth) support the idea that frogs, salamanders, and caecilians (collectively known as lissamphibians) are each other's closest relatives. Frogs and salamanders show many similarities to dissorophoids, a group of extinct amphibians in the order Temnospondyli. Caecilians are more ...
Temnospondyli (from Greek τέμνειν, temnein 'to cut' and σπόνδυλος, spondylos 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian and Triassic periods, with fossils being found on every continent.
Like the modern amphibians, they were mostly small with simple vertebrae, resembling lissamphibians in many aspects of external anatomy and presumably ecological niches. At a subclass level, it was thought that labyrinthodonts gave rise to lepospondyls, and lepospondyls to lissamphibians.
The list below largely follows Darrel Frost's Amphibian Species of the World (ASW), Version 5.5 (31 January 2011). Another classification, which largely follows Frost, but deviates from it in part is the one of AmphibiaWeb , which is run by the California Academy of Sciences and several of universities.