Chapter 5: Primates

Three types of primates Prosimians (pre-monkeys) Monkeys (Old World and New World) Apes

Common Mammal Traits Fur (or body hair in Humans) Long gestation & live birth (relative to other types of organisms) Heterodontism (different kinds of specialized teeth) Ability to maintain constant body temp (Homeothermy) Increased brain size (greater ability for learning and behavioral flexibility)

Hands & Feet Great degree of Prehensility Five digits on hands/feet (contra horses) Opposable thumb In most- divergent & partially opposable big toe Nails on all or some digits Highly sensitive tactile pads on digit ends

Question to Ponder Why are Human Feet different?

II. Diet & Teeth Lack of dietary specialization – most primates are generalized feeders eating a wide variety of foods Therefore, primates have a generalized dentition

III. Senses & Brain Vision enhanced Olfaction reduced Complex brain

Vision All primates rely heavily on vision Color vision in Diurnal primates. Stereoscopic vision Eyes in front of skull, overlapping fields of vision Accurate 3-D vision Increased depth perception Point to Ponder: Why would this be an adaptive trait? (hint: think environment)

V. Behaviors Tend to be diurnal Increased flexibility in behavior Tend to live in social groups In many primate social groups, males are permanent members – unusual among mammals.

Arboreal Adaptation Hypothesis Traditionally, the arboreal adaptation seen as the primary factor in primate evolution Selected for 3-D and color vision (why?). Grasping prehensile hands/feet to grasp Tropical arboreal environment = varied foods

Geographical Distribution

Most primates are arboreal, living in forest or woodland areas Some Old World primates do spend considerable time on land. No primate, except for humans, is fully terrestrial – all spend some time in trees.

Diet & Teeth Omnivorous w/generalized dentition Although some primates prefer some food items over others, most eat a combo of fruit, leaves, and insects. Some do eat meat (chimps & baboons) Some are leaf specialists (Colobine monkey)

Teeth Most have 4 types of teeth Incisors and canines: biting and cutting Premolars and molars: crushing and grinding

Each Primate species has a specific dental pattern

Locomotion Almost all primates are quadrapedal Many use more than one form of locomotion Long, flexible lumbar spine which provides greater propulsion from hind legs

Two Suborders Prosimii Anthropoidea Lemurs, Lorises, Tarsiers Monkeys, Apes, Humans

Prosimians: Lemurs & Lorises Most primitive Greater reliance on olfaction (long snouts) Mark territory with scent More laterally placed eyes Shorter gestation & maturation “dental comb” (projecting lower incisors & canines)

Lemur and Loris

Lemurs Madagascar Many different species (diversified in absence of competing primates) Became extinct in other areas

Lemurs Range in size from 5”, 2 oz. to +2’, 22 lbs Larger lemurs are diurnal, omnivorous Smaller lemurs are nocturnal, insectivores Many forms are arboreal, others are more terrestrial Some live in large social groups Others (Indri) are monogamous pairs

Lorises Similar in appearance to Lemurs Tropical habitats (Sri Lanka, India, SE Asia, Africa) Survived by adopting nocturnal habits Competition avoidance with monkeys

Lorises Slow, cautious climbing form of quadrupedalism Bushbabies active vertical climbers and leapers Almost entirely insectivorous Diet supplemented with fruit, gum, leaves

L & L Vision is stereoscopic, but less developed than anthropoids Color vision in diurnal, but not nocturnal Grooming claw on second toe (not fully nailed) Longer life spans than similarly sized mammals

Tarsiers Nocturnal SE Asia Mated pair & offspring Diet: insects & small vertebrates they catch by leaping from branches

Tarsiers difficult to classify Prosimian traits: Small size Grooming claws Unfused mandible Anthropoid traits Lack of Rhinarium (moist nose pad) Orbits fully enclosed by bone

Anthropoids (monkeys, apes, H.s) Generally larger body Larger brains in absolute and relative size Increased reliance on vision Fully forward placed eyes; bony plate back of eye socket; greater degree of color vision Fused mandibles; less specialized dentition Female anatomy different; longer gestation; longer maturation; increased parental care More social interaction

Monkeys ~ 70 % of all primates are monkeys Two types: Old World or Catarrhini (downward-facing nose) New World Callitrichidae Cebidae

New World Monkeys No fully opposable thumb. Wide flaring noses with nostrils that face outward Almost exclusively arboreal Prehensile tails No fully opposable thumb. With one exception, diurnal Two Groups: Callitrichidae Cebidae

Callitrichids Small Marmosets and Tamarins

Marmosets and Tamarins Most primitive monkeys Retain claws instead of nails (used like squirrels to climb trees) Twins rather than single births Family groups Mated pair 2 males & 1 female Males very much involved in infant care

Cebids Larger than callitrichids 30 species Diet varies with combo of fruits & leaves Most are quadrupedals Spider monkeys are semibrachiators

Old World Monkeys

Old World Monkeys and Apes Nostrils are set close together and face downward. Never have a prehensile tail, Can have opposable thumb.

Still finding new monkeys April 22, 2000: Conservation International announced the discovery 2 new marmoset species in the Amazon Basin of Brazil.  Both species are squirrel size.  They have been named Callithrix manicorensis and Callithrix acariensis.  Since 1990, ten new monkey species have been discovered in Brazil. 

Hominoids (apes & humans) Super-family includes: Less apes: gibbons and siamangs Great apes: gorillas, orangutans, chimps Humans (family Hominidae)

Hominoid traits Lack of tail Larger body size (except in lesser apes) Shortened trunk Different musculature in shoulder joint More complex behavior Longer infant development & dependence More complex brains

Hominoids