BIOL108 Lecture Notes - Lecture 32: Birdwatching, Archaeopteryx, Synapomorphy

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Origin of birds: birds likely evolved from the theropods. Missing link between the reptiles and dinosaurs. Aves and crocodilians are the extant groups of archosaurs: living descendants of dinosaurs. Characteristics of modern birds: 4 chambered heart. Also in theropods and mammals: amniotic egg, scales on legs, endothermic. Use metabolic energy to maintain body temperature. The feathers and layers of fat help retain body heat: derived characteristics: adaptations for flight. All of these adaptations reduce body weight! Since you will be relying on flight as the primary mode of transportation. Makes the bone very lightweight but doesn"t sacrifice strength. Wings have only one main digit and two tiny digits. No claws on wing digits in extant species. Muscular part of stomach that contracts to crush food in stomach. Preening: moves oil from the gland at the base of the tail to rest of the feathers. Contours feathers to keep in good shape. Causes tiny hooks and rays to link.