Birds - Origin Class Aves Origin /Ancestral Niche General background Archaeopteryx is the oldest fossil belonging to class Aves, late Jurassic

Birds - Taxonomy @ 9100 species in 29 orders, 2 major lineages a. Paleognathae = 5 orders of flightless birds (ratites) Includes tinamous, rheas, kiwis, ostriches, emus

Birds - Taxonomy @ 9100 species in 29 orders, 2 major lineages a. Paleognathae = 5 orders of flightless birds (ratites) Includes tinamous, rheas, kiwis, ostriches, emus b. Neognathae = the rest

Birds - Characteristics A. Feathers 1. modified epidermal scales 2. light and strong, and used for a variety of functions: a. insulation b. airfoil c. streamlining d. waterproofing e. reflecting/absorbing solar radiation f. tactile sense (like vibrissae in mammals) g. display

Birds - Characteristics A. Feathers - continued 3. structure varies depending on function a. contour feathers (1) have interlocking barbs and barbules (2) feathers are smooth and sheet-like (3) used as airfoil, for waterproofing (4) Large ones on wing and tail are “Quill” feathers

Birds - Characteristics A. Feathers - continued 3. structure varies depending on function a. contour feathers (1) have interlocking barbs and barbules (2) feathers are smooth and sheet-like (3) used as airfoil, for waterproofing (4) Large ones on wing and tail are “Quill” feathers b. down feathers (1) lack barbs and barbules (2) feathers are soft, "fluffy" – good at trapping air (3) used for insulation

Birds - Characteristics A. Feathers - continued c. filoplumes and bristles (1) have few or no barbs (2) serve as sensory structures and/or filters

Birds - Characteristics B. Musculoskeletal system 1. bones have been lightened (large air spaces) 2. skeleton is strengthened by extensive fusion of bones 3. hind legs used for body support/locomotion 4. forelimbs modified as wings joints have limited ranges of motion (to resist deformation of wing by air pressure) humerus is short, robust for insertion of strong flight muscles

Birds - Characteristics B. Musculoskeletal system - continued the wrist, hand, and finger bones are reduced in number and elongated enlarged keel on sternum for the origin of the flight muscles 5. head and beak become important tools for manipulating the environment skull is highly kinetic, capable of complex, delicate manipulations neck is relatively long (so head can reach out from body)

Birds - Characteristics B. Musculoskeletal system - continued have numerous small cervical vertebrae that interlock, so neck can be both flexible strong 6. foot (toes) often modified for locomotion and food handling

Birds - Characteristics C. The cardio-pulmonary system extremely efficient 1. four-chambered heart - complete separation of pulmonary and systemic circulation 2. Unique lung structure allows birds to live and fly at altitudes at which mammals can’t survive

Birds - Characteristics Hind limbs/feet adapted for habitats/modes of locomotion 1. cursorial (running) locomotion a. long legs to increase stride length b. reduction in surface area of toes in contact with ground 2. swimming: feet either webbed or lobed 3. raptorial: feet large with strong claws for prey capture and handling

Birds - Characteristics Modes of locomotion - continued 4. perching: four free, mobile toes approximately the same length a. special arrangement of tendons creates "pulley system", -weight of the perching bird tightens tendons curls the toes tightly around the perch b. no muscular energy expended; bird won’t fall off when it sleeps

Birds - Characteristics Modes of locomotion - continued 5. climbing: a. relatively short legs b. feet with two toes in front and two to rear c. tail with stiff feathers to act as prop 6. Others: a. ptarmigan have heavily feathered feet/toes for walking on snow b. jacaranas have very long, slender toes for walking on floating vegetation

Birds - Reproduction 1. internal fertilization 2. all species are oviparous, amniote eggs like reptiles 3. parental care ranges from virtually none to extreme

Birds - Reproduction Some reproductive strategies 1. Altricial - Young hatch early in development, require extensive parental care 2. Precocial - Young hatch well developed, require much less parental care (Know several advantages/disadvantages of each) 3. nest parasites exploit parental care of others