Exam 2 Flashcards
(104 cards)
which hypothesis is a better in terms of models of flight
Ground-Up
How did the evolution of flight provide benefits?
- Flight enhanced hunting and scavenging.
- it enabled many birds to exploit flying insects, an abundant, highly nutritious food resource.
- Flight provides a ready escape from earthbound predators.
- it enables many birds to migrate great distances to exploit different food resources and seasonal breeding areas.
- the arctic tern migrates round-trip between the Arctic to Antarctic each year.
What are the most obvious adaptations for flight
Wings
what are airfoils that illustrate the same principles of aerodynamics as airplane wings
Wings
what are the 2 hypothesis on the evolution of bird flight?
- The “ground-up” hypothesis is based on running birds with primitive wings to snare insects
- the “trees-down” hypothesis has birds through tree-climbing, leaping, parachuting, gliding, and finally powered flight.
what hypothesis fits this:
- theropod running and jumping on the ground
- use outstretched limbs and stabilizers
- fringe allowed for longer jumps
- lead to gliding and then powered flight
Cursorial (running, or ground-up)
what hypothesis fits this:
1. small theropod or theocodont jumping from tree to tree or to ground
2. fringe would slow fall
3. lead to gliding and then powered flight
Arboreal (“Trees Down”)
what kind of dinosaur features does the Archaeopteryx have
-clawed forelimbs
- teeth forelimbs
- teeth in beak
- bony tail
What came first? feathers or flight?
- feathers probably preceded flight and arose for thermoregulatory purposes.
- but, once evolved, provided a superb “preadaptation” for flight
what are the most remarkable of vertebrate adaptations
feathers
what are made if the protein keratin, the same material in reptile scales and mammalian hair and nails
feathers
do most birds have water-proof capabilities
no
may have functioned first as insulation during the evolution of endothermy and were later co-opted as flight equipment
feathers
what lacks hooks on barbules, producing a fluffiness that provides excellent insulation because of the trapped air
downy feathers
what are the stiff ones that contribute to the aerodynamic shapes of the wing and body
contour feathers
what is the stiff, central spine of a feather from which the vanes, if present, extend
Shaft
the broad, usually flat, surfaces that extend from the shaft of contour and flight feathers; the vanes are formed by interlocking barbs.
Vanes
the hollow lower portion of the feather shaft that lacks vanes
calamus
the portion of the feather shaft distal to the calamus; it is often relatively solid and supports the vanes when present
rachis
describes that portion of the vane that is relatively flat and has a defined shape
pennaceous
describes that portion of the vane for which the loose, fluffy barbs are not structured into flat vanes
plumulaceous
the regular, parallel fibers that extend from each side of the rachis to form the feather vane
barbs
the central shaft of a feather barb (from which barbules extend)
ramus
branchlets off the barbs of a feather that hook together with adjacent barbules
barbules