Modern Primates and Primate Behavior

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Modern Primates and Primate Behavior

• A Survey of Living Primates
• Prosimians

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Prosimians

• The most primitive of the primates.
• Characteristics
• Reliance on olfaction
• Laterally placed eyes
• Shorter gestation and maturation periods
• Dental specialization called the "dental comb

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• The order primate is divided into two major
  suborders, Prosimii and Anthropoidea.
• Prosimian (pre-apes) represent the most
  primitive primates, that is, they resemble the
  earliest primates.
• Prosimians, literally before monkeys, is the
  large group of primates that includes the lemurs,
  loris and the tarsiers.
• At first, prosimians were wide spread eventually
  being pushed into marginal areas as newer, more
  adaptively flexible primates evolved.
• Some modern prosimians live on the mainlands of
  Africa, India, and Southeast Asia as well as on
  the isolated islands of SE Asia.
• However, a majority inhabit the island of
  Madagascar.

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• The forty or so living species of prosimians
  exhibit a number of differences from the general
  primate pattern.
• About half of the prosimian species are nocturnal
  and so lack color vision.
• They have large eyes that can gather more light.
• Better that average sense of smell and hearing.
• To aid their olfactory sense, they have a
  protruding snout with a large receptor area
  (mucous membranes within the nose), and a moist,
  naked outer nose (like a dog or cat).
• Prosimians do have stereoscopic vision
  characteristic of primates because they need to
  judge distances in bushes and trees
• And their 3-D vision helps them to catch insects,
  a favorite food.

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• They have prehensile hands and feet.
• But the opposability of their thumbs is limited.
• Many can only touch the thumb with the other four
  digits together their digits dont move
  independently.
• Some prosimians have a claw instead of the
  typical primate nails on a couple of fingers or
  toes.
• These are known as grooming claws and are used
  both for that purpose and to help acquire food.

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What are the characteristics of this hand?
AyeAye
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• A particularly interesting prosimian (and one
  that is problematic for taxonomists) is the
  tarsier of SE Asia.
• Weighing just 4 or 5 ounces.
• They are insect eaters with powerful hind limbs
  for jumping.
• Have enlarged fingertips and toetips for added
  friction.
• They have the ability to turn their head in 180
  degrees in either direction.
• Its name comes from its elongated ankle, or
  tarsal, bones which makes its legs look like they
  bend too many times.

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Lorises

• Found in tropical forests and woodlands of India,
  Sri Lanka, southeast Asia, and Africa.
• Characteristics
• Use a climbing form of quadrupedalism.
• Some are insectivorous others supplement their
  diet with fruit, leaves, gums, and slugs.
• Females frequently form associations for foraging
  or in sharing the same sleeping nest.

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• The lorises and related mainland African species
  (pottos, angwantibos, and galagos) make up the
  Infraorder Lorisiformes.
• An infraorder is a higher, more inclusive
  classification category than a family.
• Lorises have one other form of defense that makes
  up for their slow movements.
• They have unpleasant tasting poisonous saliva
  that they lick onto their fur.
• Mother lorises also lick the fur of their babies
  which helps to protect them from potential
  predators.
• The galagos are the most numerous African primate
  other than people, however, few people see them
  because they live in dense forests and are only
  active at night.

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Below Slender Loris (Loris tardigradus)
Note the grooming claw.
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Lemurs

• Found on the island of Madagascar and other
  islands off the coast of Africa.
• Extinct elsewhere in the world.
• Characteristics
• Larger lemurs are diurnal and eat vegetable
  foods fruit, leaves, buds, and bark.
• Smaller lemurs are nocturnal and insectivorous
  (insect -feeding).

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GeographicalDistribution of Modern Lemurs
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• The lemur species of Madagascar make up the
  Infraorder Lemuriformes.
• Lemurs reached Madagascar early in primate
  evolution and became isolated reproductively from
  the African mainland about 250 miles away.
• Subsequently, they evolved into the 22 or more
  mostly arboreal species of today.
• Elsewhere, they became extinct.
• There are now three surviving families of lemurs
• 1.Lemuridae (true lemurs)
• 2.Indriidae (indris, avahis, and sifakas)
• 3.Daubentoniidae (aye-ayes)

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Family Lemuridae

• Species of the Family Lemuridae, the true lemurs,
  range from the size of a mouse to that of a large
  domestic cat.
• They have long bushy tails that are used for
  balancing as they jump from branch to branch.
• They have a well-developed sense of smell and
  often mark territorial limits with scent.
• They are omnivorous in diet, eating both plants
  and small animals such as insects and baby birds.
• Most are nocturnal and solitary.
• Some of the larger species, are primarily
  diurnal.
• They also differ from other lemurs in that they
  are mostly vegetarian and some species form large
  social groups.

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Family Indriidae

• The Family Indriidae consists of three groups of
  species indris, avahis, and sifakas.
• They are the most monkey-like of all of the
  Prosimiis in that they are relatively big.
• The indris are the largest in size, reaching
  about four feet from head to toe and weighing up
  to 14 pounds.
• The sifakas have long spring-like legs that allow
  them to jump dramatically over 30 feet from tree
  to tree.
• This evolutionary specialization of their legs
  forces them to hop rather than walk when on the
  ground.

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Left and Above Indri (Indri indri)
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Sifaka Locomotion Sifaka Acrobat
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Family Daubentoniidae

• The extremely rare aye-aye is the only surviving
  species of the Family Daubentoniidae.
• They are solitary and nocturnal.
• In addition, they have unusual hands and teeth
  for primates.
• Their elongated, narrow fingers have claw-like
  compressed nails that are used, along with their
  long, curved, rodent-like incisor teeth, to get
  at grubs under tree bark and other hard to reach
  delicacies.

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Aye Aye Daubentonia madagascariensis
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Tarsiers

• Small nocturnal primates found on the islands of
  southeast Asia.
• Characteristics
• Eat insects and small vertebrates which they
  catch by leaping from branches.
• Basic social pattern appears to be a family unit
  consisting of a mated pair and their offspring.

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• Biochemically they are close to monkeys, but
  chromosomally they are unique among the primates.
  
• Some researchers consider tarsiers to be in their
  own Prosimii infraorder (Tarsiformes).
• Others believe that they are genetically distinct
  enough to be a separate suborder (Tarsioidea).
• The 3-5 surviving tarsier species have heavy
  dependence on vision and a reduced ability to
  smell.
• Unlike the lemur and loris families, all tarsiers
  lack a long snout and a rhinarium, or moist,
  hairless pad at the end.

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• Adding to their already odd appearance, tarsiers
  can rotate their heads nearly 180, like owls.
• They have long hairless tails, except for tuffs
  on the end, like kangaroo rats.
• They also have elongated hind feet and legs, like
  galagos, which give them the ability to leap up
  to six feet.
• This provides an advantage in hunting insects and
  in avoiding predators.
• They are strictly nocturnal and arboreal.
• Today, the tarsiers' range is mostly limited to
  the Philippines, Borneo, and the Celebes Islands
  to the east of Borneo.

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Why is the Tarsier it Problematic?

• Some authorities suggest placing the tarsier in
  the second primate suborder, Anthropoidea.
• Because of its flat face
• upright posture when clinging to trunks and
  branches
• lack of the moist naked nose of other prosimians
• and some recent genetic comparisons
• Cladists goes further

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• They suggest dividing the order Primates into
  suborder based on the trait that all prosimians
  have a moist nose and that no anthropoids do.
• The former prosimians would thus be in suborder
• Strepsirhini (nose with curved nostrils), and
  the anthropoids would become the suborder
• Haporhini (simple nose).
• This later group would include tarsiers because
  of its
• nose,
• color vision,
• and other traits.

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