Dichotomous Key/Placentalia

1

 * Pulp cavity
 * Not present (thin tubes of dentine instead) - Orycteropus afer
 * Present - 2

2

 * Limbs
 * Adapted for flight or gliding - 3
 * Adapted for land movement or swimming - 4

3

 * Capability of true flight
 * Yes - ../Chiroptera/
 * No - ../Dermoptera/

4

 * Limbs adapted for swimming
 * Yes - 5
 * No - 6

5

 * Legs
 * Present or vestigial -
 * Absent - ../Sirenia/

6

 * Number of fingers
 * Five - ../Primates/
 * Other amounts or none - 7

7

 * Hooves
 * Present - 10
 * Not present - 8

8

 * Trunk presence
 * Yes - ../Proboscidea/
 * No - 9

9

 * Incisors
 * Developed, located at the front of the jaw - 12
 * Undeveloped, side teeth used for grazing - 11

10

 * Number of toes
 * Any odd number - ../Perissodactyla/
 * Any even number - ../Artiodactyla/

11

 * Teeth growth
 * Throughout lifetime - 12
 * Only during maturation - 13

12

 * Number of incisors in upper jaw
 * Four - ../Lagomorpha/
 * Two - ../Rodentia/

13

 * Presence of bony scales
 * Yes - 14
 * No - 15

14
Could be of the order ../Pholidota/ or an armadillo (family ../Dasyopodidae/)

15

 * Dentition
 * Prominent canines and carnassials - ../Carnivora/
 * Other - 16

16

 * Legs
 * Vestigial - ../Cetacea/
 * Present -

17
Could be of the orders ../Afrosoricida/, ../Macroscelidea/, ../Xenarthra/, ../Scandentia/, ../Insectivora/, ../Cetacea/