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1 Zoology Final Study Guide 1. Mammal evolution: A prehistoric therapsid group, the cynodonts, survived into the Mesozoic and evolved a high metabolic rate, increased jaw musculature, several skeletal changes, and secondary bony palate. 2. Significance of hair and warm-bloodedness? 3. Mammal reproduction: Monotremes- use left ovary and oviduct; layers added in oviduct and uterus; eggs held against abdomen with tail then sucklings held Marsupials- brief placental connection; gestation long as estrus cycle; neonates crawl to marsupium; 190 days=joey; next sibling in embryonic diapause; 2 nipples: neonate=high protein, low fat, joey=low protein, high fat Placental- placental connection until birth; interrupted estrus cycle 4. A hair grows from a follicle that is sunk into the dermis of the skin. It grows continuously by rapid proliferation of cells in a follicle. As a hair shaft is pushed upward, new cells are carried away from their source of nourishment and die, turning into the same dense type of fibrous protein, called keratin, that constitutes nails, claws, hooves, and feathers. 5. Claw- keratinized sheath on end of appendage; can be modified into hoof Antler- mesodermal frontal bone covered by velvet; burr at base cuts it off; in mature males (except caribou); shed and regrown; deer, elk, caribou Hollow horn- core of bone (frontal) projecting into hollow, cornified epidermis; grows continuously; in both sexes; permanent; cattle, sheep, goats Keratin fiber horn- fused fibers of keratin hardened; rhino Pronghorn- projection of frontal bone with horny epidermal sheath; epidermal sheath is shed; pronghorn antelope Tusk- tooth to manipulate objects; elephant, walrus, narwhal 6. Echolocation- ultrasound waves bounce back and tell direction, distance, speed, shape; dolphins use nasal passage (melon) to send out sound wave and jaws receive; bats send out with larynx and receive with ears 7. Monkeys, apes, and humans are all primates; they have a short rostrum, forward eyes, large braincase, opposable hallax and 7.... View Full Document

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