• I. Ungulates: Perissodactyla and Artiodactyla
• II. Order Perissodactyla
• III. Order Artiodactyla

I. Ungulates: Perissodactyla and Artiodactyla

1. Not a formal taxonomic division
   1. Perissodactyla="odd-fingered ungulates"
   2. Artiodactyla="even-fingered ungulates"

2. Shared features
   1. Extreme cursorial adaptations
   2. Syndactyly
   3. Hooves
   4. Herbivory

3. Cursoriality
   1. Evolution
   2. Biomechanics
      1. Increasing stride length

         1) Lengthen limbs
         2) Loss or reduction of clavicle
         3) Dorso-ventral flexion of spine

      2. Increasing stride rate

         1) More joints in limb
         2) Reduction in weight of distal limb elements
         3) Changes in muscle insertion points

      3. Other connective tissue specializations related to cursoriality and herbivory

         1) Nuchal ligament
         2) Springing ligament

4. Herbivory
   1. Problems associated with herbivorous diet
   2. Solutions
      1. Artiodactyla: rumination
      2. Perissodactyla: hind gut fermentation

II. Order Perissodactyla

1. General characteristics
   1. Unguligrade limbs
   2. Enlarged central digit carries most of body weight (mesaxonic)
   3. Elongated skull
   4. Canine teeth reduced or absent
   5. Complex ridge pattern on cheek teeth
   6. Simple stomachs with large caecum

2. Families
   1. Equidae
   2. Rhinocerotidae
   3. Tapiridae

III. Order Artiodactyla

1. General characteristics
   1. Two enlarged digits share the weight of the body about equally (paraxonic)
   2. Upper incisors and canines lost or reduced
   3. Antorbital pit in many species
   4. Males (and sometimes females) have weaponry
      1. tusks
      2. antlers
      3. horns
   5. Ruminants or non-ruminants (based on stomach morphology)

2. Suborder Suinae
   1. Suidae
   2. Tayassuidae
   3. Hippopotamidae

3. Suborder Ruminantia
   1. Camelidae
   2. Cervidae
   3. Giraffidae
   4. Antilocapridae
   5. Bovidae
   6. Moschiidae
      male with tusks
   7. Tragulidae