All extant fully aquatic mammals except the sea otter are found in two clades of exclusively aquatic species, Cetacea and Sirenia; the extinct desmostylians may also have been fully aquatic (these groups are thought to have entered the water about 50, 40 and 30 Ma ago, respectively). In contrast, semiaquatic mammals are widely distributed throughout the class. However, extant semiaquatic swimming marine mammals are restricted to Carnivora (among which, pinnipeds apparently appeared about 20 Ma ago). Semiaquatic (carnivorous) rodents have been noted as having larger than normal brains for their size, possibly as a consequence of using their vibrissae for acoustic detection of prey.
The great majority of semiaquatic birds are found within three clades whose members are mostly semiaquatic: Aequorlitornithes, Anseriformes and Gruiformes, thought to be about 64, 47 and 41 Ma old, respectively.[note 1]
Amphibians differ from other semiaquatic tetrapods in that their semiaquatic lifestyle is ancestral, rather than being the result of a secondary evolutionary trend from a terrestrial state back towards an aquatic environment. Thus, they are the only tetrapods to possess gills. All extant amphibians that are semiaquatic or fully aquatic inhabit freshwater habitats, with the exception of the crab-eating frog, which also exploits brackish habitats.
†Temnospondyls - an early group of amphibians, reaching sizes up to those of crocodiles, whose adult stage was variously fully aquatic, semiaquatic or almost entirely terrestrial. Among the aquatic forms, the Triassic trematosaurids adapted to a marine lifestyle.
Most anurans (frogs and toads), but not the fully aquatic pipids, or fully aquatic members of other families such as Telmatobiidae
^Peterhans, J. C. K.; Patterson, B. D. (1995). "The Ethiopian water mouse Nilopegamys Osgood, with comments on semi-aquatic adaptations in African Muridae". Zoological Journal of the Linnean Society. 113 (3): 329–349 (see pp. 341–346). doi:10.1111/j.1096-3642.1995.tb00937.x.
^Ilardo, M. A.; Moltke, I.; Korneliussen, T. S.; Cheng, J.; Stern, A. J.; Racimo, F.; de Barros Damgaard, P.; Sikora, M.; Seguin-Orlando, A.; Rasmussen, S.; van den Munckhof, I. C. L.; ter Horst, R.; Joosten, L. A. B.; Netea, M. G.; Salingkat, S.; Nielsen, R.; Willerslev, E. (2018-04-18). "Physiological and Genetic Adaptations to Diving in Sea Nomads". Cell. 173 (3): 569–580.e15. doi:10.1016/j.cell.2018.03.054. PMID29677510.
^Stadelmann, B.; Herrera, L. G.; Arroyo-Cabrales, J.; Flores-Martínez, J. J.; May, B. P.; Ruedi, M.; Miller, E. H. (2004). "Molecular Systematics of the Fishing Bat Myotis (Pizonyx) vivesi". Journal of Mammalogy. 85 (1): 133–139. doi:10.1644/1545-1542(2004)085<0133:MSOTFB>2.0.CO;2.
^Swanson, Paul L. (1950), "The iguana: Iguana iguana iguana (L)", Herpetologica, 6: 187–193, JSTOR3890004
^Coles, William (2002), "Green Iguana"(PDF), U.S.V.I. Animal Fact Sheet #08, Department of Planning and Natural Resources US Virgin Islands Division of Fish and Wildlife, archived from the original(PDF) on 2007-12-11
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