Birds (Class Aves)

• extant (8900+ species, 28 orders, and 190 families)

• extinct (100,000 species)

• abundant since late Cretaceous

Characteristics

• Endothermy

• integument:feathers (insulation & flight)thin, scaly, dry, & with few glands

•muscular system: large pectoral muscles

skeleton

1. weight, pneumatic bones2. beak, no jaws, & one occipital condyle3. wings & bipedal hindlimbs4. carinate sternum5. synsacrum- fused sacral/lumbar vertebrae &

ilium/ishium6. clavicles fused into the furcula (wishbone)7. uncinate process joins the ribs8. secondary palate9. reduced and fused skull

digestive system• rapid processing; high energy food

• esophageal crop for storage

• gizzard

• beak & tongue specializations

• cloaca

• pellets

excretory system

• metanephric kidney

• uric acid; no urinary bladder

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

reproduction• oviparous

• internal fertilization

• pair bonding & courtship

• songs & territoriality

• parenting behavior

• precocial -vs- altricial

bird origins

• Jurassic

• Archeopteryx

• modern birds appear in Cretaceous

Archeopteryx

beaks

feet

feather evolution• from epidermal scales; protein & beta keratin

• benefits/use

• insulation

• prey capture

• courtship display

• crypsis

feather types1. remiges- wing2. retrices- tail3. structure: calamus, rachis, barbs,

and vein4. semiplumes (insulative; no barbs)5. down (insulation)6. powder down (water-proofing)7. bristles (sensory)8. filoplumes

feathers

Anseriformes

Charadriiformes

Ciconiformes

Falconiformes

Strigiformes

Piciformes

Passeriformes