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 - #16
  • 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

17

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