BIOL-3030 Lecture Notes - Lecture 20: Cranial Kinesis, Piciformes, Altricial
Document Summary
Features uniting birds with theropod dinosaurs: forward pubis bone rotates backwards, semilunate carpal consolidation of wrist bones, 3 finger hand (after ceratosuars, clavicles become fused. Early fossil bird lineages: enantiornithines: many species, long duration lineage, world-wide, growth lines in bones low metabolism, puzzling because flying birds are typically endothermic and have a high metabolism. Hesperornis and ichthyornis: hesperornis no keel; swimmer, general characteristics. Ichthyornis large keel; lived near oceans (possibly related to modern gulls in habits: long duration species, both had teeth. Modern birds: neornithes: roughly 10,000 species, modern birds have lost all teeth, two types, paleognaths: secondarily flightless ratites (ostrich, emu, etc. , old jaw, don"t fly, neognaths: most modern birds, new jaw, flying capabilities. Paleognaths: flying tinamous and flightless ratites, distribution of ratites may reflect former unified southern landmass gondwana, ratites have reduced wings and keel, legs are strengthened for running, only 2 toes less weight while running.
