BIOL 2030 Lecture Notes - Lecture 19: Trailing Edge, Synsacrum, Skeletal Pneumaticity
Document Summary
Topic 1: outline subphylum vertebrata; aves (birds) 2: feathers, skeleton, flight muscles, gas exchange, evolution. Birds evolved from saurischia, they evolved from the lizard-like hips: birds evolved from group called sauropods. Sinosauropteryx: theropod dinosaur: intermediate to dromeosaurs, bone structure: lacked twisting wrist which birds have and use in flight, had filament (not really feathers but something intermediate?) Dromeosaurs (velociraptor: quite successful in life; latest fossil up to about 70 million years ago. Protarchaeopteryx: close descendent of same lineage as dromeosaurs, had true feathers, sternum shape not consistent with birds. Contour feathers covering body and differentiated flight feathers . Wings and reduced fingers: differences with birds: Long tail: two hypotheses, arboreal theory (trees down) Selective pressures favored increased distance and accuracy: terrestrial theory (ground up) Wings evolved as traps to catch prey. Further refinements assisted in horizontal jumping and balanced landing. Hypothesized to be descendent of same lineage of archaeopteryx. Short tail; more similar to common day birds.
