BIO 2135 Lecture Notes - Lecture 20: Pennaceous Feather, Bird Flight, Sauropsida
28 Mar 2017
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Document Summary
Beta-keratinized scales, claws and feathers (more durable, more protective) Articulated plates stretchy skin in between so the body can expand. Feather = a scale pushed from the bottom, but folded on itself barb that grows, then unfolds feathers evolved into their branched shapes from original bristles. First feathers were probably ornamentation for competition in mating. Hooklet and barbule system on each barb. Different types = bristles, down feathers, contour feathers, filoplumes. Birds = moult in cycles to replace their feathers, bits at a time. Flight has arisen 4 times in the living world. Tree-down = launch themselves out of the tree with their mouths open, glide to the ground, eventually learn how to flap, evolve. Ground up = originally thought that feathers helps to capture insects out of the air, then eventually used flight to escape. Begin to see the regulation of body temperature: Set of muscles attached to the pelvic girdle.
