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Molecular studies of extant amphibians based on multiple-locus data favor one or the other of the monophyletic alternatives and indicate a Late Carboniferous date for the divergence of the lineage leading to caecilians from the one leading to frogs and salamanders, and an early Permian date for the separation of the frog and salamander groups.
Caecilians have small or absent eyes, with only a single known class of photoreceptors, and their vision is limited to dark-light perception. [17] [18] Unlike other modern amphibians (frogs and salamanders) the skull is compact and solid, with few large openings between plate-like cranial bones. The snout is pointed and bullet-shaped, used to ...
The origins and evolutionary relationships between the three main groups of amphibians are hotly debated. A molecular phylogeny based on rDNA analysis dating from 2005 suggests that salamanders and caecilians are more closely related to each other than they are to frogs, and the divergence of the three groups took place in the Paleozoic or early Mesozoic before the breakup of the ...
The three modern orders are Anura (the frogs), Caudata (or Urodela, the salamanders), and Gymnophiona (or Apoda, the caecilians). [14] 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. [ 15 ]
Blue poison dart frog. Herpetology (from Greek ἑρπετόν herpetón, meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (including snakes, lizards, turtles, crocodilians, and tuataras).
Procera is a hypothetical clade of amphibians that includes salamanders and caecilians but not frogs. A close relationship between salamanders and caecilians is a competing hypothesis to the more widely supported view that salamanders and frogs are each other's closest relatives within a clade called Batrachia. Procera was proposed as a clade ...
A higher proportion of salamander species than of frogs or caecilians are in one of the at-risk categories established by the IUCN. Salamanders showed a significant diminution in numbers in the last few decades of the 20th century, although no direct link between the fungus and the population decline has yet been found. [83]
The Batrachia / b ə ˈ t r eɪ k i ə / are a clade of amphibians that includes frogs and salamanders, but not caecilians nor the extinct allocaudates. [1] The name Batrachia was first used by French zoologist Pierre André Latreille in 1800 to refer to frogs, but has more recently been defined in a phylogenetic sense as a node-based taxon that includes the last common ancestor of frogs and ...