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
Contour Feathers
Covers most of the body
Aerodynamics
Protection
Flight Feathers
Larger and stiffer than contour feathers
Flight feathers on the wings (Remiges)
Flight feathers on the tail (Retrices)
Remiges
Flight feathers found on wings
Primary: called “manus”
Secondary: Called “ulna” (antebrachium)
Down feathers
Positioned between flight and contour feathers
- insulation
Chicks have natal down feathers
Bird Bones
Light but strong (high CaPO4 concent.)
Pneumatic bones
Pneumatic bones and examples
Bones with diverticula (invasions) of air sacks
Examples: Vertebrae, pelvis, sternum, costal bones, humerus, femer
Bird Skull
Evolved from diapsid reptilian skull
- Enlarged cranium
- Jaws toothless
- Skull prokinetics
Skull prokinetics
Premaxilla and nasal bone from hinge with frontal bone
Upper jaw can be raised as lower jaw depressed
Bird Lungs
Lung site of gas exchange, not air sacks
Unlobed
1/10th size of humans, just as heavy
Bird Air Sacks
Thin walled extensions of bronchi
Blind-ending
Key role in respiration but not gas exchange
Bird Heart and Circulatory system
Double circulation system Heart completely divided Higher metabolic rate than humans Higher blood pressure Chook: 350-470bpm Quail: 1000bpm
Double circulation system in birds
1) Pulmonary
2) Systemic
Bird: Male Reproduction
Males have Phallus
- tubercle on ventral wall of vent
- Protrusible in ducks and geese
At copulation: Vent everted in both sexes and phallus pressed to females cloaca
Bird: Female Reproduction
Left ovary and left oviduct Right ovary and oviduct regress in embryo Ovary contains large yolk-filled oocytes Oviduct is the site of fertilization Oviduct has 5 regions
Bird Ear
Similar to mammals External ear covered by covert feathers Middle ear similar to humans Contain tympanic membrane Inner ear similar to mammals
Bird: Brain
Proportionally small (exception corvids)
Cerebellum: relatively large (coordination of muscle and balance during flight)
Optic lobes: Very large
Most intelligent birds
Pigeons, Crows, and Parrots
