• I. Order Rodentia
• II. Order Lagomorpha

I. Order Rodentia

1. Convergence

2. Most notable characteristic: Teeth
   1. Incisors
   2. Cheek teeth
      
      • complex occlusal surface 1
        
      • complex occlusal surface 2
   3. Diastema
   4. Complex muscles to control chewing and gnawing

3. Major groups
   1. Protrognaths: ancestral condition (ex. Aplodontidae)
   2. Sciuromorphs: squirrel-like
   3. Myomorphs: rats, mice
   4. Hystricomorphs: guinea pig and porcupine

4. Selected families
   1. Aplodontidae (mountain beaver)
      
      • skull
   2. Sciuridae (tree squirrels, ground squirrels, flying squirrels)
      
      • skull
   3. Castoridae (beaver)
      
      • skull
   4. Heteromyidae (kangaroo rats)
      
      • enlarged auditory bullae
   5. Muridae (rats and mice)
   6. Hystricidae (Old World porcupines)
   7. Erethizontidae (New World porcupines)
   8. Cavidae (guinea pigs, mara)

II. Order Lagomorpha

1. Characteristics related to diet
   1. Teeth
      1. Incisors
      2. No canines
      3. Cheek teeth

2. Characteristics related to mode of locomotion (quadrupedal saltatory)
   1. Digitigrade/ plantigrade
   2. Skull
      1. Fenestration
      2. Jointed
   3. Soles of feet are furred
   4. Tail is short or absent

3. Families
   1. Ochotonidae (pikas)
      
      • skull
   2. Leporidae (desert cottontail rabbit, antelope jackrabbit)
      
      • skull

Lagomorph? Artiodactyl?