Dichotomous Key/Selachimorpha

1

• Anal fin
  • Present - #2
  • Not present - #3

2

• Dorsal fins
  • One - Hexanchiformes
  • Two - #5

3

• Body shape
  • Flattened - Squatiniformes
  • Fusiform - #4

4

• Snout length
  • Long - Squaliformes
  • Short - Pristiophoriformes

5

• Fin spines
  • Present - Heterodontiformes
  • Not present - #6

6

• Mouth position
  • In front of eyes - Orectolobiformes
  • Behind eyes - #7

7

• Nictitating membrane
  • Present - Carcharhiniformes
  • Not present - Lamniformes