ANTHROPOLOGY Los Angeles Zoo Visit or Online Los Angeles Zoo Research

profileprissjimenez
primatetaxonomypt1.ppt
Home>Science homework help>ANTHROPOLOGY Los Angeles Zoo Visit or Online Los Angeles Zoo Research

Insectivores

Common shrew

Star mole

Tree Shrew

This small order of tree shrews was at one time placed in the midst of controversy: is it a primate (order Primates) or an insectivore (order Insectivora)? For several years, different groups placed the tree shrews in one of these orders. Finally, this issue was resolved in 1984 when they were placed in their own order, called Scandentia. Some researchers still argue that they are the most primitive of the primates, however. Tree shrews are remarkably squirrel-like in appearance, with a bushy tail and long fur. However, they lack the prominent whiskers of a squirrel, and the snout is pointed like that of a shrew. They range in size from 8-16 inches, with half their length being in the tail. The tail can either be fully-furred (tree shrew), slightly hairy (smooth tailed tree shrew) or completely naked (pentailed tree shrew). Tree shrews are omnivores, and have large eyes and excellent hearing. They can be found in Asia, New Guinea, Philippines, and Australia. There are 19 species in 1 family:

Tree Shrew

An Overview of the Primates

  • Characteristics of Primates
  • Primate Adaptations
  • Survey of the Living Primates
  • Endangered Primates

An Overview of the Primates

  • Primates -Members of the order of mammals which includes monkeys, apes, man and prosimians.
  • Primatologists-Scientists who study the evolution, anatomy, and behavior of nonhuman primates.
  • There are about 200 types of primates on Earth today.

p.147

Trends in Primate Evolution

  • Primate evolutionary trends center around: Hand, eyes, brain, face, skeleton and social behavior.

Primate Characteristics:
Limbs and Locomotion

  • Retention of five digits on hands and feet-Pentadactly
  • Digit lengths adapted to lifestyles (long for arboreal, short for terrestrial)
  • Nails instead of claws.
  • Opposable thumb-ability to touch the face of the thumb to the face of the index finger.
  • Vs. Non-opposable-shrews, moles
  • Functionally opposable-Prosimians, monkeys, apes

Completely opposable-Hominidae

  • Tactile pads at the ends of digits.
  • Dermal ridges on face of palm and feet, fingers, etc.

Primate Characteristics:
Limbs and Locomotion

  • Tendency toward erect posture.
  • Flexible, generalized limb structure.
  • Hands and feet with a high degree of prehensility. Prehensile-grasping as by the hands and feet of primates.
  • There are two different kinds of grip:
  • Power grip-When you hold something in the palm of the hand and clutch it. Ex-holding on to ones arm. All primates have this.
  • Precision grip-This is when you hold something between the thumb and index finger. This requires opposability of thumb and index finger. Ex-holding a pencil or pen. Only humans have a true precision grip.

Characteristics of Mammals

  • Heterodontism-having different kinds of teeth that perform different functions; characteristic of mammals, whose teeth consist of incisors, canines, premolars, and molars. Varied dentition allows for a variety of foods and the ability to get more nutrients out of the food eaten.
  • Important for homoeothermy-maintaining constant body temperature.

More primitive animals such as fish, reptiles and amphibians have homodontism

  • Homodontism-Having all the same type of teeth. Typically these are pyramidal in shape.
  • Food is swallowed whole or in big chunks. Individuals don’t get nearly the same amount of nutrients out of the food they eat.

Primate Characteristics:
Diet and Teeth

  • Trend toward lack of dietary specialization.
  • Trend toward generalized dentition.
  • Dental Formula-Number and type of teeth found in each quadrant (1/4th) of mouth. Usually different super families or even families of mammals can have different dental formulas.
  • There is a general loss of size and number of teeth through primate evolution. This seems to be tied to the reduction of the lower face (decrease in prognathism) through primate evolution.

Old World

Monkeys,

Apes and man

The main changes to the head during human evolution are the enlargement of the brain case and the shortening of the face. The reduction of the face so marked that today wisdom teeth fail to erupt properly in a large proportion of the population.

An example of an abscess probably caused by an impacted 3rd molar. A case of septicemia.

Primate Characteristics:
Sense and the Brain

  • Eyes move toward front of head.
  • Only primates have the special combination of Color Vision and Depth perception (3D vision).
  • Rod and cone retina for color vision
  • Decreased reliance on smell.
  • Expansion and increased complexity of the brain.

Primate Vision

Primates’ forward- facing eyes enable depth perception, a vital adaptation to like in the trees that has a selective advantage beyond arboreal life

(B) In most primates, such as the gibbon, the eye orbit is fully enclosed. In animals such as the lemur, a postorbital bar lines the back of the eye orbit but does not fully enclose it.

*

Stereoscopic Vision. The fields of vision overlap, and the optic nerve from each eye travels to both hemispheres of the brain. The result is true depth perception.

Primate Cranial Anatomy

  • The primate face is shortened.
  • Eye sockets are enclosed by a postorbital bar and back of eye in tarsiers, monkeys, apes and man has an orbit that has a postorbital plate.

Binocular & Stereoscopic Vision

  • binocular vision
    Vision characterized by overlapping visual fields provided by forward facing eyes; essential to depth perception.
  • stereoscopic vision
    Condition where visual images are superimposed on one another. Provides for depth perception, or the perception of the external environment in three dimensions

The Brain

  • Brain: trend toward increasing size and complexity, especially in cerebral cortex.
  • One of the major leaps that occurred in mammalian evolution was the large increase in the cerebrum. The cerebrum is associated with intelligence.
  • Intelligence-the ability to learn. All mammals are intelligent. The primates are among the most intelligent.

The Brain

  • But the biggest distinction between humans and the rest of the animal kingdom as concerns the brain is in the neo cortex.
  • We have the biggest neo cortex in relation to body size of all known animals.
  • The neo cortex is associated with abstract thought, symbols, symbolic language, the ability to ponder our past, present and future. Also it is associated with sense of self identity. We alone know some day we will die. Possible exception might be the apes.

Comparison of Brain Types

*

The Human Brain with Major Parts and their Functions. The lobes and the motor cortex are all a part of the neocortex.

Primate Characteristics: Maturation, Learning and Behavior

  • Efficient fetal nourishment with long gestation, fewer offspring and delayed maturation.
  • Dependence on flexible, learned behavior.
  • Trend toward living in social groups and permanent association of adult males with the group.
  • Tendency to diurnal activity patterns.

Three Theories of Primate Evolution

Primate characteristics are the result of

adaptation.

Three theories:

  • Arboreal Living -Traditional view that primate characteristics can be explained as a consequence of primate diversification into arboreal habitats. Good eyes developed to judge distance of next tree limb. Grasping hands to hold on or else fall to the ground and die. Natural selection is constantly in action.
  • Arboreal-Tree living: adapted to life in the trees.

Three Theories of Primate Evolution

  • Cartmill’s Visual predation -view that primates first adapted to shrubby undergrowth and the lowest tiers of the forest canopy. Grasping hands needed to grab insects. Good eyes needed to judge distance of insect to be grabbed.
  • Rise of angiosperms (flowering plants) - provided nectar, seeds and fruits, required visual and tactile discrimination.