Lecture 10 DA Flashcards
Birds have scales and feathers that are analogous to what in reptiles?
They are analogous to reptile scales.
What are bird feathers made of?
Keratin.
What limb was modified to be wings in birds?
Forelimbs.
How many occipital condyles do birds have?
1.
What kind of skull do birds have, and how does this affect their beak? Why is this imprtant?
Most have a kinetic skull, allowing for a more dextrous beak. Important as they have no forelimbs for manipulation.
Is the birds beak bony or keratinised? Why?
Keratin. Keeps it light.
Do birds have teeth?
No.
How many chambers do bird hearts have? What other reptile is it the same as, and what does it differ from?
- Similar to crocodile and dinosaurs, but not any other reptile.
What are the eggs of birds like?
Hard with a calcareous shell.
True or false
Birds are both homeotherms and endotherms?
True.
What is the most diverse vertebrate after fish?
Birds.
Birds have a great biogeopgraphical range due to what?
Flight and homeothermy.
What contributes to a birds light skeleton?
Are pneumatic - filled with air cavities.
Is the birds skull fused into one piece or jointed together? What is the advantage of this?
It is fused as one piece. Makes it sturdier, allowing efficient muscle use.
What are the brain and eye sockets of birds like?
Large.
Does a birds vertebral column have joints or is it fused?
They are fused.
What is the synsacrum?
Fused trunk vertebra in birds.
What is the pygostyle?
Fused caudal vertebra in birds.
What is the neck of a bird like?
Elongate, s shaped, flexible.
Are the vertebrates of a birds neck fused?
Unfused.
How is a birds ribcage made more rigid?
Ribs are braced against each other with uncinate processes.
How is a birds sternum specialised for flight?
Has a large keel for flight muscle attachments.
What forms the wishbone/furcular, and what does it act as?
Fused clavicles form the wishbone, and acts as a spring for wing movement.
When rotating their wing, what allows the bird to flex their wrist sideways? Why is this action important?
The lunate wrist bone allows wrist to flex sideways, important for creating lift.
Where doe feathers form from?
Epidermis.
Describe the structure of a feather.
A central quill and shaft. Barbs form a flat vane on either side.
How do barbs of a birds feather stay zipped together?
Have overlapping barbules, linked together by small hooks.
Are feathers molted?
Yes, at least once a month.
What are the 5 types of feathers?
Contour Semiplumes Down deathers Bristles Filoplumes
What are the 3 types of contour feathers, and what is their purpose?
Flight - wing, primary and secondary
Tail - for displays
Covert - between flight and tail feathers, covers their base
What are semiplume feathers used for?
Between and under flight feathers, mostly for insulation.
What are down feathers used for?
Lie underneath contour, for insulation. Are fluffy.
What are bristles used for?
Used as filters, or sensory, around the mouth, eyes, and nostrils.
What are filoplumes used for?
Decorative or sensory.
Do down feathers interlock?
Are fluffy, dont interlock.
Do bristles have a shaft and vane?
Just a shaft, no vane.
Do filoplumes have a shaft and vane?
Just a shaft, no vane.
What two forces are flight driven by? How does a bird generate them?
Thrust - from beating wings.
Lift - from air movement over air foil shaped wing.
What two feathers are responsible for generating the two forces necessary for flying?
Thrust - primary wings at wing tips.
Lift - wing shaped by secondary wings.
What does flight at a low speed require? what is a consequence of this?
Requires a steeper angle of attack, risk of stalling.
What two slot types are used to prevent stalling in birds?
Alula - produced by thumb bone and its feathers.
Slots between primary feathers, formed as theyre spread out.
How is turbulence prevented in bird flight?
Tapered wings.
Is thrust generated on both the upstroke and the downstroke of wings? Why/Why not?
It is generated in both, due to the rotation and bending of the wing, due to wrist flexibility conferred by lunate.
What angle of attack is maintained in upstroke and downstroke? What does this allow?
Positive angle of attack. Allows diverse agility - steep takeoff, hovering etc.
What muscle is responsible for the downstroke? what can be said of its tendon?
Pectoralis. Nothing noteworthy regarding its tendon.
What muscle is responsible for the upstroke? What can be said of its tendon?
Supracoracoideus. Has a long tendon attachment.
Where do the two key flight muscles insert to?
Are they antagonistic?
Both insert to the keel of the sternum and on the humerus. Are antagonistic.
Keeping the two key flight muscles in what position lowers the centre of gravity? What advantage does this have?
Keeping them both ventral (rather than one dorsal as in humans) lowers centre of gravity, allowing more flight stability.
what structure allows air flow to be continuous in birds?
Tubelike parabronchi, rather than blind ending alveoli.
How many cycles of inhalation/exhalation are required to pass air through the entire system in birds?
2 cycles.
Describe what happens to air when it goes through a birds respiratory system.
Inhaled air enters posterior sacs, then through fine parabronchi, exchanging O2.
Stored in anterior sacs during the next inhalation.
Released with the second exhalation.
What is tha dvantage of having continuous air in birds?
Provides larger O2 supply, for higher metabolism demands of flight.
Do the blood circulation system of birds have a higher efficiency of O2 vs other reptiles/mammals?
yes.
What are the brains of birds like, and why?
Well developed brain, and sensory system to meet demands of flight and long distance hearing/vision.
What size is the cerebellum of birds?
Large, for coordinating muscle movement.
Do birds have a large optic lobe?
Yes.
Do birds have symmetrical ear openings? Why?
No, allows them to locate sounds.
What action aids birds in locating sounds?
Head tilt.
What is an adaptation by owls to aid in sound focus?
Have facial riff of stiff feathers, acting as a parabolic reflector to focus sounds.
How much food do birds eat?
Up to 100% of their body weight, due to flight demands.
Where is food stored in birds? Where are they grinded?
Stored in the crop, grinded in the gizzard.
How long does food stay in the birds stomach?
Pass rapidly through.
What do the crop and gizzard compensate for?
Lack of hands or teeth for food manipulation.
How do birds reduce their water intake?
Excreting highly concentrated uric acid.
What are the advantages of migration (3)?
Broadens reource base
Maintains temperatures experienced
Prevents permanent predation pressure in one location.
How do birds migrate?
By sight, magnetic sensing, and astronomical cues.
During long flights, what can birds do to reduce water intake?
Can burn muscle vs fat, as it produces more water.
What lineage are birds found in?
Archosauria.
What dinosaur did birds evolve from?
Theropods
What is the transition species of birds and dinosaurs called?
Archaeopteryx.
Are feathers necessary for flying?
No.
For what primary purpose were feathers thought to have been used for in birds?
Thought to have developed for insulation. Adapted later for flying, a preadaptation.
What are the two possible ways of flight originating?
Trees down - began by gliding down from perch, but dinosaur ancestors were ground dwellers not climbers.
From ground up - began by leaping for insects, but no living gliders launch from the ground.
What are the two superorders of birds, and what are their flight statuses?
Paleognathae - large flightless birds
Neognathae - flight birds
What are the stermuns of neognathae vs paleognathae like?
Neognathae - keeled sternum
Paleognathae - flat sternum
What are stromatolites? What do they have inside them?
Layered rocks containing sediment and cyanobacteria.
Have fossilised remains in their layers.
Where the first cells heterotrophic or photosynthetic?
Heterotrophic.
What released oxygen?
Photosyntheic cells.
What was a consequence of oxygen release?
Development of the ozone layer, for UV protection.
What are some hypotheses for the cambrian explosion (4)?
- Sufficient O2 in atmosphere.
- Mutations in developmental genes (hox genes).
- Adaptive ratiation to fill ecological niches, and arms race (ie competition).
- Climate change - end of an ice age, breakup of the supercontinent.
The breakup of which supercontinent is believed to have contributed to the cambrian explosion? Why?
Rodinia. Allowed development of more coastal areas, where life evolved, Coincided with a warmer earth.
What hampered evolutionary progress prior to the Rodinia breakup/cambrian explosion?
Massive ice age in rodinia.
What did the permean mass extinction coincide with?
Supercontinent formation, pangea, altering temperature.
What are some hypotheses over the causes of the permean mass extinction (3)?
- Supercontinent pangea formation.
- A lot of volcanic activity, high CO2 in atmosphere, nuclear winter.
- Reduced oxygen in the ocean.
What happened in the cretaceous era?
Extinction of dinosaurs.
what happened after the cretaceous era?
Earth cooled, mammals evolved. Grasslands spread, leading to grazers and humans.
