Birds Flashcards
Birds evolved from?
predatory dinosaurs
Intermediates fron Jurassic (3)
1) Archaeopteryx
2) Aurornis
3) Anchiornis
General features of Archaeopteryx, Aurornis, Anchiornis
Clawed digits on forelimb
sharp teeth
long bony tail
Specialized derived traits for Archaeopteryx (2)
Flight feathers
Fused clavicles for Furcula (wish bone)
Furcula
Wish Bone
Strengthens thorax for flight
Which ancestor contained the feathers of modern birds
Archaeopteryx
Oviraptorosaurs had comparatively (long/short) forelimbs but (long/short) feathers
Short forelimbs
Long feathers
Theropod (Digit length)
small IV and V digits
Digit III the longest
Coelophysoids (digit length)
Digit V lost
Digit II and III equal length
Allosaurids and Dromeosaurids (digit length)
Digit IV lost
Digit II longer than III
Adaptations which gradually lead to flight (5)
1) Loss and fusion of bones (vertebrae and bones of pelvic girdle)
2) Reduction in body size
3) Outer cortex of bones: Thinner but more dense
4) Bones are hollow but have Trabeculae
Trabeculae
Cross bridges of bones within long portion for stabilization and allowing bones to be more light weight
3 Aspects of bird evolution (besides hollow bones)
1) Sternum became larger
2) Forelimbs became longer than hindlimbs
3) Teeth were lost repeatedly in different lineages
Birds are the (#) largest class of vertebrates
Second largest
Successful attributes of bird evolution (2)
1) Endothermy
2) Flight
Bird Skin
1) Thinner & highly vascularized
2) Thin skin in feathered areas (10 cells thick)
3) Dermis thinner than mammals
4) Comb and wattles thickened and heavily vascularied for increased arterio-venous anastomoses
Bird Brood patch
Breast of incubating birds
Thickened and heavily vascularized
Loss of feathers
Heat transfer to eggs
Bird Beak
Keratinized structure
Grown continually
Bird Spurs
Bony core and keratinized sheath
Especially in make chook and turkey
Develops after 6 months of age
Bird Scales
Section of highly keratinized epidermis
Bird Uropygial Gland (4)
1) Found at the dorsal surface of tail
2) 2 Lobes that open to single papilla
3) Tuft of feathers
4) Lipoid secretion (waterproofs and moisturizes feather/beak/scales)
Pterylae
Feather arranged in well-defined and linear tracts
Apteria
Featherless areas exist between the pterylae
3 Types of Feathers
1) Contour feathers
2) Flight feathers
3) Down feathers