• I. Introduction
• II. Order Xenarthra
• III. Order Pholidota
• IV. Order Tubulidentata

Edentates

I. Introduction

1. Xenarthra (=Congulata and Pilosa), Pholidota and Tubulidentata formerly a single order
2. Lumped together because
   1. They're all unusual
   2. Some members of each group have reduced teeth and eat ants/termites
   3. Tend to have limbs modified for digging
   4. They all have low reproductive rates

II. Order Xenarthra (formerly Edentata)

1. General characteristics of the order
   1. Edentata means "without teeth"
   2. A tendency towards rigidity of the spine
      1. Xenarthran processes on vertebrae (especially lumbar)
      2. Fusion of vertebrae with pelvic girdle
      3. Fusion of cervical vertebrae

   3. Were once very diverse; some interesting ones:
      1. glyptodonts: had turtle-like shell; most completely armored of all vertebrates
         fossil skeleton
         artist's rendering
      2. Megalonyx : giant ground sloth
         fossil skeleton
         museum reconstruction
         artist's rendering

2. Families
   1. Dasypodidae (armadillos)
      1. 8 genera, 20 species
      2. Characteristics

         1.) Carapace
               *covers most of the body
               *made of dermal bone plates covered by epidermal scales
               *varies from a complete protective covering when animals roll into a ball, to a more loose fitting one that doesn't completely cover
               * attached to axial skeleton by muscles and ligaments (not in direct contact with the skeleton)

         2.) Sparse hair
         

         3.) Teeth
               *Lack incisors and canines
               *Teeth are cylindrical and rootless

         4.) Most are terrestrial, some fossorial

         5.) Well equipped for digging

         6.) Eat insects and insect larvae, with occasional plant material, eggs, berries, etc.

   2. Bradypodidae (3-toed sloths): 1 genus, 3 species
      skull
      
      
   3. Megalonychidae (2-toed sloths): 1 genus, 2 species
      skull
      
      
   4. The following information applies to both families
      1. General characteristics

         1.) Arboreal (have great difficulty moving on the ground)
         2.) Often move upside-down on the underside of branches
         3.) Long-limbed, with forelimbs longer than hind
         4.) Toes are fused ( syndactyly )
         5.) Cervical vertebrae are variable in number (6-9)
         6.) Teeth
               *Lack incisors and canines
               *Cylindrical, homodont, rootless teeth
         7.) Rudimentary tail
         8.) Long, coarse hair on which blue-green algae grows
         9.) Herbivorous: eat buds, flowers, fruit
         10.) Very, very low metabolic rate and poor temperature regulation

   3. Myrmecophagidae (anteaters)
      1. 3 genera, 4 species
      2. Characteristics

         1.) Very long, tubular rostrums, very small mouths
         2.) Long, sticky tongue that moves rapidly
         3.) No teeth
         4.) Insectivorous
         5.) Crush insects with thickened stomach (pyloric portion)
         6.) Have large front claws for opening up termite mounds, tearing up rotting logs, etc.

      3. Examples

         1.) giant anteater
         2.) tamandua
         3.) silky pygmy anteater

III. Order Pholidota

1. General characteristics of the order
   1. Name means "scaly ones"
   2. Major diagnostic character is the scales that cover their bodies
      1. Made of keratinized epidermis
      2. Periodically replaced as they wear and fall out
      3. Leaf shaped
      4. Cover top of head, top and sides of body and limbs, and entire tail
      5. Parts without scales are hairy

   3. Arboreal ones have prehensile tails, terrestrial ones have short tails
   4. Long, tubular rostrum
   5. Long sticky tongues (extends all the way back into the chest cavity when retracted)
   6. No teeth
   7. Horny epithelium with "teeth" in the pyloric region for smashing insects
   8. Digging limbs
      1. Plantigrade
      2. 5 digits
      3. Long claws

2. Ecology and behavior
   1. Insectivorous
   2. Some are terrestrial, some arboreal

IV. Order Tubulidentata

1. General characteristics of the order
   1. May be most closely related to the elephants and hyraxes, but often lumped with edentates.
   2. The smallest living order
   3. Aardvark means "earth hog" in Afrikaans (appropriate because they are pig size and shape and are semifossorial)

2. Morphology
   1. Skull is elongated
   2. Teeth
      1. No incisors or canines
      2. 5 cheek teeth top and bottom
      3. Cheek teeth are oval or figure-8 shaped
      4. Teeth have numerous tubular pulp cavities running vertically through each tooth (gives the order its name)

   3. Pig-like snout
   4. Long tongues
   5. Big ears
   6. Long, gradually-tapering tail with thick base
   7. Thick skin with bristles
   8. Digits have strong, hoof-like claws

3. Ecology and behavior
   1. Eats termites, ants, other insects
4. Picture of baby aardvark
5. One more...