primate adaptation and evolution taxonomic order of mammals that includes prosimians (lemurs),...
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Primate Adaptation and Evolution
• Taxonomic order of mammals that includes prosimians (lemurs), monkeys, apes, and humans.
• Estimated 230-270 species.
• Primates are diverse but share common features.
Common Characteristics
• Vision is dominant sense.
• Eyes face forward rather than to the side as in other mammals.
• Light-sensitive cells of retina packed closely together results in good vision.
• Eye position enables depth perception and gauging distances known as stereoscopic vision.
• Color vision.
More Characteristics
• Arboreal or tree-dwelling.
• Adaptations for survival in trees.
• Flexible shoulders and hip joints for locomotion, climbing, and swinging from branch to branch.
• Shoulders adapted for arm movement in different directions. In some species, such as apes, ball-and-socket shoulder joints provide mobility.
• Flexible elbows, allow palm of hand to turn in many directions.
• Hands and feet have nails rather than claws as seen in other mammals.
More Characteristics
• Hands used for food manipulation or grasping objects due to flexible or opposable thumbs.
• Rounded head and flattened face compared with other animals.
• Relative to body size, largest brain of any terrestrial mammal. Large brain size related to cerebrum, part of the brain involved in thinking and memory.
• Complex brain reflected in diverse behaviors and social interactions.
Primate Origins• Earliest identified primate
from fossil record is Purgatorius that lived about 60 to 65 million years ago.
• No living species like Purgatorius but prosimians come close. Notice the tail.
• Primates divided into two sub groups: prosimians and anthropoids.
Prosimians
• Small bodied. Include lemurs and tarsiers. Found in Africa and Southeast Asia.
• Nocturnal. Have large eyes to spot insects in the dark.
• Fossil evidence: prosimians evolved about 50 to 55 million years ago.
Three Major Anthropoids • New World monkeys of South and
Central America.
• Old World monkeys of Africa, Asia, and Europe.
• Hominoids: Asian and African apes and humans.
• More complex brain than prosimians - increased intelligence.
New World Monkeys• Live in rain forests South and Central
America.
• Include marmosets, capuchins, howlers, sakis, and spider monkeys.
• Live in trees (arboreal). Endangered – deforestation.
• Long, muscular prehensile tail (used to grasp and wrap around branches like another arm or leg).
New World Monkeys
• First anthropoids to evolve.
• Range in size from 6 inch pygmy marmoset to 3 foot howler monkey.
• Wide nostrils, circular, spaced apart.
• No buttock pads or cheek pouches.
• Fossils date back 30 to 35 million years.
Old World Monkeys
• Found in hot, dry environments (Africa) and cold environments (Japan).
• Both arboreal and live on the ground.
• Colobus, baboons, macaques, mandrills, proboscis monkeys.
• No prehensile tail.
• Fossils date back 20 to 22 million years.
Old World Monkeys• Larger than New World monkeys.
• Narrow downward pointing nostrils.
• Longer hind legs than forearms.
• Flattened nails on fingers and toes.
• Prominent buttock pads.
• Tails, not prehensile, used for balance. Diurnal.
• Divided into subfamilies. Cheek-pouched monkeys and leaf-eating monkeys.
Hominoids • Bipedal (walk on two legs ).
• Include Asian and African apes, humans, and direct ancestors.
• Theory: between 5 to 8 million years ago in Africa, hominoids diverged into 2 lines that eventually became chimpanzees and humans.
• Environmental change caused some hominoids to leave the trees and move to the ground to find food.
• To move efficiently on the ground while avoiding predators, humanoids evolved to become bipedal.
• No fossil support but DNA of humans and chimpanzees is similar.
Ape Characteristics
• Orangutans, chimpanzees, gibbons, bonobos, and gorilla.
• Long, muscled arms and legs for climbing and walking. No external tail.
• Arboreal or live on the ground.
• Capable of social interaction.
• Chimpanzees most closely related hominoid to humans.
More Ape Characteristics
• Larger and heavier than monkeys.
• More upright body posture than monkeys.
• Broad chest; muscular forelimbs.
• Rely on vision rather than smell; shorter noses than monkeys.
• Large brain to body size ratio compared with other animals.
• Live in Africa and Asia.
• Fossils date back 37 to 40 million years.
Great Apes• Smooth mostly hairless face ; round ears. No
cheek pouches.
• Thumb shorter than fingers; opposable.
• Arms longer than legs and big toe is also opposable. Can walk bipedally.
• Can distinguish colors; rely mostly on vision and hearing rather than smell.
• Wide range of vocalizations and facial expressions. • Intelligent, capable thinkers; able to problem solve
and learn language.
Primate Hands and Thumbs• Vary in structure and manipulative ability.
• Hand of tarsier has opposable thumb and slender fingers with adhesive pads adapted for grasping branches.
• Hands of orangutan adapted for swinging from branch to branch; fingers serve as hooks for hanging on branches and thumb is short to not get in the way.
• Hand of gorilla has longer, more opposable thumb than orangutan; fingers are shorter.
• Human hand most manipulative ability; long thumb more opposable ; fingers more dexterous and capable of free movements.
Primate Matrix