Edentates

1. Xenarthra (=Congulata and Pilosa), Pholidota and Tubulidentata formerly a single order called Edentata
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

Later Pholidota and Tubulidentata were given order designation, but sloths, armadillos and anteaters were all lumped together and called Xenarthra. Xenarthra is now considered a superorder, consisting of the orders pilosa and cingulata.

Distribution - Neotropics (and Cingulata invading N. America)

Position in the Eutherian phylogenetic treehttp://www.sciencemag.org/content/vol294/issue5550/images/large/se4810026001.jpeg

1. General characteristics of these orders
   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. Order Cingulata
   1. Family 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.

3. Order Pilosa
   1. Family Bradypodidae (3-toed sloths): 1 genus, 3 species
      skull
      
      
   2. Family Megalonychidae (2-toed sloths): 1 genus, 2 species
      skull
      
      

      The following information applies to both families of sloths

      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. Family 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