| Batrachia | |
|---|---|
_crop.jpg) | |
| Australian green tree frog (Litoria caerulea) | |
 | |
| Fire salamander (Salamandra salamandra) | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Subclass: | Lissamphibia |
| Superorder: | Batrachia Latreille, 1800 |
| Clades | |
TheBatrachia/bəˈtreɪkiə/ are aclade ofamphibians that includesfrogs andsalamanders, but notcaecilians nor the extinctallocaudates.[1] The name Batrachia was first used by French zoologistPierre André Latreille in 1800 to refer to frogs, but has more recently been defined in aphylogenetic sense as anode-based taxon that includes thelast common ancestor of frogs and salamanders and all of its descendants. The idea that frogs and salamanders are more closely related to each other than either is to caecilians is strongly supported by morphological and molecular evidence; they are, for instance, the only vertebrates able to raise and lower their eyes.[2] However, an alternative hypothesis exists in which salamanders and caecilians are each other's closest relatives as part of a clade called theProcera, with frogs positioned as thesister taxon of this group.[3]
The earliest batrachians are thestem-frogsTriadobatrachus andCzatkobatrachus from the Early Triassic, about 250 million years ago. However, severalmolecular clock estimates place the first appearance of the Batrachia (the time at which frog and salamander lineages diverged from each other) before the Early Triassic. Most estimates place the divergence in thePermian[4] but some put it as far back as 367 million years ago in theLate Devonian (which is whentetrapods are thought to have started to emerge fromfishapods).[5] However, there is no evidence of lissamphibians or lissamphibian-like animals in the fossil record at this time. The tetrapod groups that are hypothesized as ancestors of modern amphibians (lepospondyls andamphibamid temnospondyls) appear in theLate Carboniferous, roughly 300 million years ago. Large fossil tetrapod assemblages are known from theArtinskian stage of theEarly Permian about 275 million years ago and contain no lissamphibians, suggesting that the Early Permian may be an upper bound for the age of Batrachia.[6]
