The Batrachia are a clade of amphibians that includes frogs and salamanders, as well as the extinct allocaudates, but not caecilians. 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 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, but an alternative hypothesis exists in which salamanders and caecilians are each other's closest relatives as part of a clade called the Procera, with frogs positioned as the sister taxon of this group.