Animalia-Mammals

Animalia-Mammals - Mammals = amniotes with fur & milk...

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Mammals Monotremes: egg laying mammals -- duck- billed platypus, echidna --ant eater no placenta -- oldest living mammal group Marsupials: pouched mammals --live birth and born immature --260 species –possums earliest evidence in North America dramatic radiation in Australia Placental mammals --fully formed placenta --live birth and fairly well developed
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Mammalian characteristics 4,000 species 30% rodents 25% bats World-wide distribution 170 mya marsupial line split mammals marsupials monotreme s Ancestral mammals– 225 mya Therapsids 170 mya
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Mammalian characteristics 1. Mammary glands –modified sweat glands 2. Fur --true hair and hair follicles 3. Posture --legs located ventral to the body 4. Jaws –consist of one movable mandible specialized teeth (incisors, canines, molars, premolars) distinct jaw hinge 1. Three middle ear ossicles incus, anvil, stapes 1. Non-nucleated RBCs
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Mammalian characteristics cont 1. Four-chambered heart 2. Alveolar lung –expanded surface area 3. High metabolic rate 4. Endothermic –controlled internal body temp. Heat production thru metabolism, muscle activity shivering heat loss –thru fur, fat, circulatory control, hibernation and torpor
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This note was uploaded on 12/09/2009 for the course BIO 200 taught by Professor Herreid during the Spring '07 term at SUNY Buffalo.

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Animalia-Mammals - Mammals = amniotes with fur & milk...

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