Gelada (Theropithecus gelada) Fact Sheet: Physical Characteristics

Body measurements (summarized from Bergman and Beehner 2013)

Body shape (from Bergman and Beehner 2013 unless otherwise noted)

• Large-bodied, terrestrial primate
  • Similar in size and appearance to true baboons (Papio spp)
• Head
  • Skull large with a deep, massive muzzle
  • Ears concealed by hair (Hill 1970)
• Limbs
  • Moderately long (Hill 1970)
• Tail
  • Medium-length, shorter than in true baboons
  • Tuft of hair at tip

Facial characteristics (from Bergman and Beehner 2013 unless otherwise noted)

• Facial hair
  
• Minimal hair on the face
• Grayish hair often surrounds the face
• Skin
• Black
• Eyes
  • Lids whitish or pale pink
    • Sharply contrasts with the black face when the brow is retracted in aggression
• Muzzle
  • Projects forward, though less so than in true baboons
  • Rounded at end
  • Dorsal surface concave, with a longitudinal (along its length) series of folds (Hill 1970)
• Lips (Hill 1970)
  • Deep
  • Upper lip highly mobile
• Cheeks
• Indented
• Neck
  • Red hour-glass shaped area of bare skin
  • Extends onto the chest
  • Color intensity is variable
    • Age, reproductive stage, recent activity, and social position affect hue

Adult pelage (from Bergman and Beehner 2013 unless otherwise noted)

• Hair
  
  • Coarse and wiry (Hill 1970)
  • Long, thick, golden mane (mantle or cape) on adult males
• Back
  • Pale, brown to near black
  • Tinged with gold, red, and gray tones
• Hands and feet
  
  • Elongate (Hill 1970)
  • Black nail on each finger (Vram 1923)
  • Pads naked and black (Hill 1970)
• Buttock
  
  • Hairless
  • Black, calloused
  • Four-lobed ('four-leaf clover') appearance

Highly dimorphic (from Crook 1966 unless otherwise noted)

• Body size variation
• Adult males c. two times heavier than adult females
• Appearance
• Adult male
  • Hairy cape that extends to the shoulders (description above)
  • Canine teeth enormous
• Adult female
  • Coat color more uniform (Bergman and Beehner 2013)
  • Lack cape (Bergman and Beehner 2013)
  • Skin of neck and chest pale pink, ringed with vesicles that swell to indicate the preovulatory period (Bergman and Beehner 2013)
    • Brighter red when in estrus or pregnant (Bergman and Beehner 2013)
  • Superficially similar to macaques

Foraging adaptations

• Hands and fingers
• Thumb elongated and index (2nd) finger abbreviated (from Bergman and Beehner 2013; Jablonski 1993 unless otherwise noted)
  • Together enable pincer-like grip; aids in picking grass leaves
  • Highest degree of thumb opposability of any non-human primate
• Padded buttocks (Bergman and Beehner 2013)
  • Calluses and pads on hind-end facilitates 'scooting' along the ground during foraging
• Dental specialization
• Molar (teeth) specialized to resist wear and provide a grinding surface (Dunbar and Bose 1991)
  • High crown with enamel extending below the gumline
  • Deep surface grooves

Chromosome number

• 21 pairs of chromosomes (2n=42) (Chiarelli 1962)

Subspecific characteristics (from Bergman and Beehner 2013 unless otherwise noted)

• Northern gelada (Theropithecus gelada gelada)
  • Mane pale brown to chocolate
  • Thin, iron-gray hair surrounds skin patch on chest
• Southern gelada (T. g. obscurus)
  • Mane dark chocolate to near black
  • Extensive, pure-white hair surrounds skin patch on chest
    • Extends onto the inner sides of upper arms

Similar primates (from Bergman and Beehner 2013)

• Hamadryas baboon (Papio hamadryas)
  • Live within the range of geladas
  • Pale face, red buttock, and light-colored hair distinguish this species
  • Lack bare, red throat and chest patch
• Olive baboon (Papio anubis)
• Live within the distribution of geladas
• Lack of hair tuft at tip of tail distinguishes this species
• Lack bare, red throat and chest patch

Geladas are easily identified by the bright-red, hour-glass shaped, exposed skin on their neck and chest. Adult males are nearly two times heavier than females and sport a cape (mane) of hair which extends to their shoulders.

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