21. Birds Flashcards
First bird?
Archaeopteryx (ancient wing)
- Jurassic (150 mya)
- Crow-sized
Shared characteristics of birds and dinosaur ancestors?
- Bipedal, 3 hind toes
- Carnivorous
- 4-chambered heart
- Similar lungs
- Feathered
- Hollow bones
- Parental care of eggs and juveniles
Archaeopteryx
- bird characteristics?
- non bird characteristics?
Bird: feathers + wings
Non-bird: teeth + bony tail
Is archaeopteryx ancestor of modern bird?
Not quite. More like shared ancestor.
Major characteristics of birds?
- Amniotes
- Endothermic
- 4-chambered heart (completely separate pulmonary and systemic circuits)
- Feathers
- Most fly
- Diverse beaks (due to diverse diets)
most unique features of birds?
Feathers (not flying)
Beaks
How do bird thermoregulate?
Endotherms - generate their own internal heat through metabolic processes (vs ectotherms)
How do endotherms generate heat?
We are less efficient at metabolism - we produce excess heat when we transform food into ATP (or ATP into ADP)
Homotherm and Heterotherm?
Other axis - not in opposition to endo/ectotherm. Heterotherm allows their temperature to be modified by outside temperature.
Endotherm and maintenance of body temperature in lab? How?
Endotherm: stable.
Metabolic rates indirectly proportional (kind of) to temperature of lab
(exception: too hot, MR increases)
Behavioural thermoregulation?
Move between hot and cold microhabitats depending on temperature (goes on rock in the sun, hides under ground, etc.)
3 types of thermoregulation
- Behavioural
- Physiological
- Physical
Physiological thermoregulation?
Blood flow, sweat, panting, shiver, etc.
Physical thermoregulation?
Insulation (fur, feathers, fat, surface area, volume)
Physiological regulation, in mammals, is a ….. feddback system in the ….
Negative
Hypothalamus
Difference in ears size in rabbits?
Big ears in warm climates to lose more heat
Small ears in cold climates to lose less heat
Why do we have fever?
Adaptive to fight infections, who don’t do well in higher temperature - could be an issue to take a fever reducer
Issue with birds and respiration?
- Flying + endothermy requires high amounts of oxygen (much more efficient and complex than in mammals)
Birds respiratory system - ….. flow of air through lungs
Unidirectional
How are birds super efficient in breathing?
Numerous air sacs (8-9) - anterior and posterior
- allows unidirectional air flow
Ventilation in birds
Breath 1
1. Air is drawn into posterior air sacs
2. Air is proppelled?
Breath 2
3. Same air is drawn into the anterior air sacs
4. Same is air is propelled out thru nares
In birds, it takes ………. for any breath of air to…
- 2 cycles
- Come in and come out
4 evolution of flight
- Insects
- Pterosaurs
- Birds
- Bats
Gliding?
Not the same as flying
Snakes, fishes can glide. (planner)
Type of evolution in flight?
Convergent - due to common environment, not common ancestor
Adaptions for flight?
- hollow bones (lighter)
- sternum enlarged and keeled (plus profond, so more surface area to attach large flight muscles)
- Feathers
Why did feathers evolve?
Not for flight! Probably for insulation (found in theropod dinosaurs)
Functions of feathers
- Insultaion
- Flight
- Sensoring
- Lining nests
Feathers are all composed of?
Keratin (derived from scale)
Scales in bird?
- In feathers
- Scaled skin on their legs
How do wings enable flight?
Wings create pattern of air flow below and above the wing that are different
- Above wing: lower pressure, higher speed of air
- Under: higher pressure, lower speed of air
(Particles must move faster to get over bump)
More evidence for which theory of evolution of flight?
Ground-up (not tree-down)
What would expect evidence for ground up?
- Ancestors more close to those that use to be in the ground (vs. climbing)
- Ancestors were running
