EARTH 7 Lecture Notes - Lecture 14: Recapitulation Theory, Avialae, Velociraptor
Document Summary
Becomes important for flight: bowed ulna. Gives space for muscles that move the hands. Becomes important for flight: highly stabilized tail. The struts become longer than the vertebrae itself, solidify and become a sort of coil. Great counter weight for running: reverse pubis. Birds are maniraptors: semi-lunate carpal present, bowed ulna present, highly stabilized tail present, but very reduced, reverse pubis present. Skeletal and dental features suggest is was an herbivore. Egg incubators: parental care, bird-like brooding behavior, warm-blooded. Recent (2005) discovery of oviraptorosaurian with two eggs in her pelvic canal: eggs usually arranged in pairs within nests. Like crocodiles; birds only have one functional ovary. Birds (lay one egg at a time); crocodiles lay a whole bunch of eggs at. Have large, retractable claw on toe #2: later lost, retractability maintains the sharpness. Several groups with such feathers appear to have lost the ability to fly. Late jurassic end cretaceous, diverse and worldwide.
