BIOL 111 Lecture Notes - Lecture 20: Thermostat, Theropoda, Archaeopteryx
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The ancestor to birds was probably a theropod dinosaur. Shared characteristics of birds and dinosaur ancestor: bipedal, 3 hind toes, carnivorous, 4-chambered heart, similar lungs, feathered, hollow bones, parental care of eggs and juveniles. Feathers and wings bird (avian) characters. Teeth and bony tail non-avian characters. 4-chambered heart (completely separate pulmonary and systemic circuits) Diverse beaks; diverse diets (carnivores, herbivores, nectivores) Source of heat: ectotherms: absorb external heat (i. e. amphibians, endotherms: generate their own internal heat through metabolic processes (i. e. mammals) Less efficient at transforming energy (i. e. lose energy as heat when converting food into atp or atp into adp) Amniote phylogenyendotherms maintain relatively constant body temperature in a lab. In field, lizards actually maintain body temperature at different temperature than its environment by entering shaded and non-shaded areas. Lizard maintains its body temperature between upper and lower limits by moving between hot and cold microhabitats.