Dichotomous Key/Amphibia

Amphibia Animalia Animalia Chordata Chordata Vertebrata Vertebrata Amphibia Amphibia 1 Number of vertebrae Nine or fewer - 2 More than nine - 3 Bold text 2: Salientia Tailwagging muscles Present - 6 Not present - 7 3 Tail Present in all life stages - 5 Not present in all life stages - 4 4: Gymnophiona 5: Caudata Narrow grooves between each nostril and the upper lip Present - Plethodontidae Not present - 14 6 Inscriptional ribs Present - Leiopelmatidae Not present - Ascaphus truei 7 Endochondral ossifications in the hyoid plate (distinct from parahyoid bones) Present - Bombinatoridae Not present - 8 8 Narrow epipubic cartilage plate Present - Discoglossidae Not present - 9 9 Astragalus and calcaneum Fused - Pelodytidae Not fused - 10 10 Metatarsal spade Present - 13 Not present - 11 11 Tongue shape Paddle-shaped - Megophryidae Other or not existent - 12 12 Tongue Present - Neobatrachia Not present - Pipidae 13 Elongate atlantal neural arch Present - Rhinophrynus dorsalis Not present - Pelobatidae 14 Fertilization Internal - 15 External - #16 15: Salamandroidea Premaxillae Fused - 18 Separated - 19 Dicamptodontidae, Salamandridae, Ambystomatidae, Proteidae, Rhyacotritonidae, Amphiumidae 16 Metamorphosis Present (fully or partially) - 17 Not present - Sirenidae 17: Cryptobranchoidea Metamorphosis Partial - Cryptobranchidae Full - Hynobiidae 18 Operculum Present - 20 Not present - 21 19 Operculum Present - Salamandridae Not present - Amphiumidae 20 Lacrimal bone Present - Dicamptodontidae Not present - Ambystomatidae 21 Bilaterally paired septomaxillary bones Present - Rhyacotritonidae Not present - Proteidae __NOTOC__