1. Birds (Class Aves) extant (8900+ species, 28 orders, and 190 families) extinct (100,000 species) abundant since late Cretaceous

2. Characteristics Endothermy integument: feathers (insulation & flight) thin, scaly, dry, & with few glands muscular system: large pectoral muscles

3. skeleton 1. weight, pneumatic bones 2. beak, no jaws, & one occipital condyle 3. wings & bipedal hindlimbs 4. carinate sternum 5. synsacrum- fused sacral/lumbar vertebrae & ilium/ishium 6. clavicles fused into the furcula (wishbone) 7. uncinate process joins the ribs 8. secondary palate 9. reduced and fused skull

4. digestive system rapid processing; high energy food esophageal crop for storage gizzard beak & tongue specializations cloaca pellets

5. excretory system metanephric kidney uric acid; no urinary bladder

6. respiratory & circulatory systems 1. air sacs attach to pneumatic bones; 9X the air volume of lungs 2. aid in heat dissipation 3. no diaphragm 4. syrinx- voice box 5. four chambered heart 6. nucleated red blood cells

7. reproduction oviparous internal fertilization pair bonding & courtship songs & territoriality parenting behavior precocial -vs- altricial

8. bird origins Jurassic Archeopteryx modern birds appear in Cretaceous

9. Archeopteryx

10. beaks

11. feet

13. feather evolution from epidermal scales; protein & beta keratin benefits/use insulation prey capture courtship display crypsis

14. feather types 1. remiges- wing 2. retrices- tail 3. structure: calamus, rachis, barbs, and vein 4. semiplumes (insulative; no barbs) 5. down (insulation) 6. powder down (water-proofing) 7. bristles (sensory) 8. filoplumes

15. feathers

16. Anseriformes

17. Charadriiformes

19. Ciconiformes

20. Falconiformes

21. Strigiformes

22. Piciformes

23. Passeriformes