Dichotomous Key/Chordata

1

 * Vertebrae
 * Present -
 * Not present -

2

 * Feeding method
 * Filter - Urochordata
 * Jawless, sucking mouth - Myxini

3

 * No options yet

4

 * Jaw
 * Present -
 * Not present - Petromyzontidae

5

 * Skeletal material
 * Cartilage - Chondrichthyes
 * Bone -

6

 * Primary habitat (does not include secondary aquatic animals such as newts, aquatic snakes, whales, dolphins, ....)
 * Aquatic -
 * Terrestrial or amphibious -

7

 * Metamorphosis (not within egg or womb)
 * Present - Amphibia
 * Not present -

8

 * Scales
 * Present - Reptilia
 * Not present -

9

 * Feathered wings
 * Present - Aves
 * Not present - Mammalia

10

 * Fins
 * Lobed -
 * Rayed - Actinopterygii

11: Sarcopterygii

 * Ability to breathe air
 * Present - Dipnoi
 * Not present - Actinistia