gel_lec_15 (unfinished)

gel_lec_15 (unfinished) - Yes& No-Scaling effect(if less...

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Lecture 15 – 2/17/10 Were dinosaurs warm-blooded? When and why did we start talking about warm-blooded dinosaurs? 1969 Dinonychus - Very active - Must have warm-blood What does “warm-blooded” mean? - Homeothermy: keeps temperature constant - Endothermy: ability to generate heat inside body to help homeothermy - Warm-blooded: maintain high body temperature (>30 C) with endothermy – mammals and birds - Core temperature fluctuates throughout the day, only a few degrees C - ¾ (72.4%) of endothermic heat from internal organs, ¼ (27.6%) from skins and muscles How do reptiles compare with mammal in their thermoregulation? - Reptiles are ectothermic (rely on external heat) - Can fluctuate between 15-20 deg Celsius - In morning, use external heat to warm up from sleeping - Mammals need constant energy to remain warm - The colder the weather, the more energy we consume Do body size and growth rate matter?
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Unformatted text preview: Yes & No-Scaling effect (if less surface than volume, suffer and benefit-Heat generation is related to body volume-Heat removal is related to surface-Doubling size causes overheating, half-size causes over cooling-For larger animals – easier to keep constant body temp in low ambient temperature-Easier to be overheated in high ambient temperature - gigantothermy How did dinosaurs control their body temperature?-Warm-blooded control body temperature with nasal turbinate, membrane maintains heat and moisture when we exhale. It also warms up and moistens oxygen as we breathe in. dinosaurs may have had nasal turbinate, but not truly warm blooded-Large dinosaurs may have been gigantothermic homeotherms-Small dinosaurs had feather (insulation) but no turbinate; they are partial endotherms...
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