lissamphibian

Lissamphibia is the clade that includes all living amphibians: frogs and toads (Anura), salamanders and newts (Urodela or Caudata), and caecilians (Gymnophiona). It represents the crown group of Amphibia, distinct from extinct prehistoric amphibian lineages. The origin of lissamphibians is subject to ongoing study, but the earliest unequivocal fossils date from the Triassic, with diversification of the three living orders occurring in subsequent eras.

Key features commonly associated with lissamphibians include moist, permeable skin that can participate in cutaneous respiration, and a life cycle often involving an aquatic larval stage that metamorphoses into a more terrestrial or semi-aquatic adult. Many species lay eggs in water or damp environments; eggs hatch into larvae that typically develop through metamorphosis, though some lineages exhibit direct development or neoteny. A characteristic dental condition is pedicellate teeth, with crowns and bases separated by a dentine zone. Reproduction and behavior vary widely among the three orders, with considerable diversity in parental care, habitat use, and physiology.

Diversity and distribution: there are thousands of extant lissamphibian species, with frogs and toads (Anura) by far the most diverse, followed by salamanders (Urodela) and caecilians (Gymnophiona). They occupy a broad range of habitats worldwide, from tropical forests to temperate regions, wetlands, and subterranean environments. They are ecologically important as predators and prey and are often indicators of environmental health.

Conservation: many lissamphibians are threatened by habitat loss, pollution, climate change, and emerging diseases such as chytridiomycosis caused by Batrachochytrium fungi.