Lecture 25 Vertebrates - Birds Flashcards
Birds evolved from
Small, predatory dinosaurs
The earliest bird is
Aurornis
Three intermediates between dinosaurs and birds are
-archaeopteryx
-aurornis
-anchiornis
Aurornis have (5)
-clawed digits on forelimb
-sharp teeth
-long bony tail
-Dino-fuzz-like down feathers
-larger flight like feathers but unable to fly
Archaeopteryx have (5)
-clawed digits on forelimb
-sharp teeth
-long bony tail
-flight feathers
-fused clavicle
A “reptile that flies” is
Archaeopteryx
Having a fused clavicle
Strengthens thorax for flight
A key feature of birds are
Feathers
Feathers likely appeared in
Compsognathids
New types of feathers was seen in
Oviraptorosaurs
Changes in ___ accompanied the development of feathers
Bones (fusion, loss, and strengthening of skeletal)
First Therapods dinosaurs had forelimbs with
Small 4 and 5 digits, digit 3 was the longest
Coelophysoids had forelimbs with
A loss of digit 5, digits 2 and 3 were equal in length
Allosaurids and Dromeosaurids had forelimbs with
Digit 2 longer than 3, loss of digit 4
Evolutionary characteristics uniquely adapted for flight include (4)
-reduction, loss and fusion of forelimbs, vertebrae, and pelvic girdle
-reduction in overall body size
-thin but dense bones (reduction of weight)
-hollow bones or have trabeculae
Sternum of birds became (2)
-larger
-evolved a central keel to anchor flight muscles
Forelimbs of birds became (2)
-longer than hind limbs
-main form of locomotion (ie. flying)
Teeth of birds were
Lost repeatedly in various lineages (too heavy)
The second largest class of vertebrates are
Birds
How many species of birds are there
9,600
Success of bird evolution is due to (2)
-endothermy (ie. ability to control body temp)
-flight (ie. ability to adapt to wide range of environments)
The beak of birds is (3)
-dependent on diet
-keratinised structure derived from skin
-grow continuously
The uropygial gland is (4)
-on the dorsal surface of the tail
-not present in all species, mostly found in water birds
-is two lobes that open to a single papilla
-has a lipoid secretion which helps waterproof and moisturize
Four types of feathers
-contour
-flight
-down
-natal down
Contour feathers (3)
-cover most of the bird’s body
-used for aerodynamics
-protects body
Flight feathers are
-larger and stiffer than contour feathers
Remiges are
Flight feathers on the wing
Retrices are
Flight feathers on the tail
Primary wing flight feathers (remiges) are located on
The manus
Secondary flight feathers of the wing (remiges) come from
The ulna (antebrachium)
Down feathers are (2)
-positioned between contour and flight feathers
-provide insulation
Natal down feathers are
Feathers in chicks used for insulation
Bones of the bird are (2)
-Light but strong
-Have a high concentration of Calcium Phosphate
Pneumatic bones of the bird are (2)
-diverticula of air sacs
-large and strong without being heavy
Birds have a ___ than reptiles
Larger cerebellum
The skull birds evolved from
Diapsid reptilian skull
Prokinetic refers to
The premaxilla and nasal bones forming a hinge with the frontal bone (especially seen in parrots)
The sternum of birds is (2)
-the attachment site for flight muscles
-absent in flightless species except penguins
Nuts (typo??) of birds are (3)
-relatively small, flattened and rectangular
-unlobed
-dense
Air sacs are (4)
-thin walled extensions of bronchi
-play a key role in respiration but minimal role in gas exchange
-poorly vascularized (ie. no blood supply)
-function as bellows (drive air unidirectional)
Birds have a ___ circulation system
Double (systemic and pulmonary)
The heart of birds is
Completely divided into 2 atria and 2 ventricles
Birds have a ____ compared to mammals
Higher metabolic rate
Male birds have a
Phallus - tubercle on ventral wall of vent
Female birds only utilize
The left ovary and oviduct
The ovary of birds has
Very large, yolk filled oocytes
The oviduct of birds (2)
-is the site of fertilization
-can store sperm for weeks
The brain of birds is
-proportionally small compared to body size (except crows)
Optic lobes of birds are
Very large
The cerebellum of birds is (2)
-relatively large
-coordinates muscle activity and balance in flight
