Dichotomous Key/Amphibia

1

 * Number of vertebrae
 * Nine or fewer - 2
 * More than nine - 3

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2: Salientia

 * Tailwagging muscles
 * Present - 6
 * Not present - 7

3

 * Tail
 * Present in all life stages - 5
 * Not present in all life stages - 4

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 -

15: Salamandroidea
Dicamptodontidae, Salamandridae, Ambystomatidae, Proteidae, Rhyacotritonidae, Amphiumidae
 * Premaxillae
 * Fused - 18
 * Separated - 19

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