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 - #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