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Biology 4242 – First Exam Key
(Just noticed that the numbers of the questions didn't come through the cut and
paste process.)
(10 pts) Definitions:
Theropod- Bipedal saurischian dinos maybe/probably the ancestors of
birds. First appeared way back in Triassic. Coelosaurs (prob bird ancestors)
known only from Cretaceous deposits. (This answer much more detailed than
necessary!)
Thecodont Primitive reptile, ancestral to dinos, crocs, and maybe birds.
Retrix One of the tail feathers (plural is retrices)
Extant Not extinct
Key adaptation Adaptation that opens the evolutionary door to a new
suite of ecological niches.
a. (4 pts) Label the three parts of this feather (A, B, and C) and name the
feather parts that are “velcroed” together to form “A”
A – Vane
B – Shaft or rachis
C – Calamus or quill
D - Barbs are 'velcroed' together by barbules and
barbicels
b. (1 pts) Is this feather
pennaceous or plumulaceous?
(2 pts) How many orders of birds are there? 27-30
(2 pts) Why don’t ornithologists agree on this number? Some orders may
be lumped (Rattites, and (a separate issue) – Flamingos may belong in their own
order or may be in with another order-Ciconiiformes?)
(4 pts) True or false:
__T_ The first bird appears in the fossil record in the Jurassic period about
160 million years B.P.
__T_ Fossil dinosaurs with feathers may actually be birds misidentified as
dinosaurs.
__F_ Because of their high metabolic rate, most birds were able to survive the
mass extinction event that wiped out the dinosaurs at the end of the Mesozoic
era. Most birds from the Mesozoic went extinct.
__F_ The current weight of evidence, and most paleontologists support the early
reptilian (before dinosaurs) origin of birds, although some very reputable
scientists disagree.
(4 pts) Give four characteristics of birds that make them such good study
subjects for so many fields of biology? Size, distributed everywhere,
mostly diurnal, on same freqs of sound and light that we use, well known, easy
to identify, not too many nor too few, wide range of behaviors, learn songs very
similar to the way we learn speech.
(3 pts) What is the correct sequence of the three Eras of geological time
(number them with 1 being the most recent).
__2__ Mesoozoic
__3__ Paleozoic
__1__ Cenozoic
Convergent evolution.
(3 pts) What is it? Unrelated species evolve
similar characteristics because they use the same ecological niche. Don’t have
to be in separate locations, although they often are.
(2 pts) Name 2 pairs of birds that demonstrate the phenomenon. Sunbirds
and hummingbirds, toucans and hornbills, alcids and penguins. (et al.)
(2 pts) How do we distinguish primary and secondary flight feathers?
Where they grow on the wing--Off the hand (primaries) or ulna (secondaries)
(3 pts) List 3 pieces of evidence that convince us that birds evolved from
reptiles.
Nucleated red blood cells
6 features of skull alone, including:
single occipital condyle
ear (single) and jaw bones (many)
articulation of lower jaw onto quadrate
sclerotic ring supports eye
laterally expanded braincase
ankle location
scales on legs (in fact feathers are just fancy scales)
similar yolked egg
female birds and some reptiles are heterogametic sex (ZW)
(3 pts) What is the “Modern Synthesis” and roughly when did it take place?
The marriage of Darwin’s theory of natural selection and Mendelian
genetics in the early part of the 20th cent.
(2 pts) What is the name of the biogeographic or faunal region…
…we are in here in NC? Neactic
…found south of the Isthmus of Panama? Neotropical
(3 pts) We have long been taught that the long bones of birds are hollow to
reduce weight, yet the skeleton of a bird weighs about the same as the skeleton
of a comparable sized mammal, which has solid bones. What explains this apparent
paradox? Bird bones are stronger, and hence denser. If they were solid
they would weigh much more than a mammal of similar size. Because they’re
hollow, they weigh about the same.
(4 pts) Match the Ornithologists with their major accomplishments:
H__Broke the gender gap and pioneered
A. Ted Parker
studies of birds using color bands.
B. Rosemary Grant
C. Spencer Baird
Audubon__Was a draft-dodging artist who traveled
D. Alexander Wilson
much of the eastern US shooting and
E. Robert MacArthur
drawing birds for his monumental
F. Roger Tory Peterson
The Birds of America.
G. Joseph Grinell
H. Margaret Morse Nice
D__ An immigrant from Scotland, this
I. John James Audubon
pioneering ornithologist traveled around eastern K. A. A. Allen
North America in the early 1800s studying
Birds. He wrote the first American Ornithology
book, entitled, appropriately enough,
American Ornithology.
Roger Tory Peterson__Wrote and illustrated the first field
guide that made identification of birds
in the field accessible to amateur bird watchers.
(2 pts) What are the two forces that birds must overcome to remain airborne?
Lift and drag
(4 pts) Strangely enough, there has been some controversy over the physics
behind lift. Very briefly, what are the two explanations? Bernoulli’s
principle (increased distance over upper surface of wing reduced air pressure
relative to below the wing providing net upwards force) and Newton’s 3rd
Law-every action has an equal opposite reaction (birds’ wings force air down-the
reaction is the bird is force up).
The avian skeleton and flight:
(3 pts) List three adaptations in the avian skeleton from its reptilian
ancestors that make it easier to fly. Loss of bones, hollow bones,
fusion of bones, keeled sternum, forelimbs became wings, loss of teeth.
(Anything about feathers shouldn’t have gotten points—they’re not part of the
skeleton.)
(2 pts) Every adaptation has its cost (there really is no such thing as a free
lunch). For one of the modifications you listed in part “a” explain the cost
associated with it. What did birds give up when the skeleton was evolved for
flight? Hollow bones – more fragile (to compensate, they’re denser).
Lost bones-loss of the functions those bones performed (i.e. fingers in the
hand, or with the change from forelimb to wing, loss of ability to manipulate
food), for teeth, obviously some tough food needs to be ground, so some birds
eat gravel and most develop a very muscular gizzard.
Flight muscles:
(2 pts) What are the two major antagonistic flight muscles in birds?
Pectoralis major and supracoracoideus.
(1 pt) Where does the muscle that elevates the wing originate? On the
sternum.
(1 pt) Where does it insert? Head of the humerus (deltoid crest).
(1 pts) What’s unusual about this arrangement? Expected to originate on
the back.
(1 pts) How does the unusual location help birds in flight? Lowers the
center of gravity. (You had to mention
lowering the COG. Some students just wrote that it
created a center of gravity—everything has a center of gravity. The arrangement
‘moves’ the COG in the bird to a more stable position.
(4 pts) What was unique about New Zealand that permitted birds to "go wild," in
an evolutionary sense, once they arrived? Name 2 birds that fill unusual
ecological niches there. There were no mammalian COMPETITORS (not
predators) so many niches were open. The lack of mammalian predators led to the
large number of flightless birds, but would not have explained the adaptive
radiation of the New Zealand avifauna.
(2 pts) What term describes this rapid, broad speciation? Adaptive
radiation
A – Carolina Chickadee
B- Goldfinch
C- American Robin
D- Passeriformes (Can’t believe anyone missed this. Remember, always guess
Passeriformes if you don’t know!)
Stage 2: 17 Feb 2011
(5 pts) Judging by their beaks, what does each of these birds eat?
A. Pine nuts (I was pretty liberal with this as it’s hard to see the
strange beak in the picture.)
B. Big ol’ seeds—large and hard ones.
C. Aquatic vegetation and plankton filtered through the beak.
D. Fish and other large aquatic organisms.
E. Anything it wants! More specifically, other animals, often large prey.
(2 pts) Why was the timing of the discovery of Archaeopteryx lithographica
important? It was right after Darwin published The Origin of Species and
provided the much needed missing link between two groups of organisms.
(4 pts) What of the following makes us believe that Archaeopteryx lithographica
was capable of powered flight?
__ Its long tail was used as a rudder to fly through forests (this could
just be for gliding)
_x_ Its asymmetrical flight feathers
__ Its keeled sternum – didn’t have one
__ Its lack of teeth – had teeth
(2 pts) What was special about the rocks it was found in and why was this
important? Very fine grain provided conditions to preserve the feathers.
(3 pts) List three functions of feathers. Flight, insulation,
communication, protection, sensory input (filoplumes).
(5 pts) What do we mean when we refer to redundancy in evolution? Why is it
important? Cite an example. For a structure (or gene) to change (evolve)
into a new function, something else has to be there to continue to do what the
old structure did before it started changing. A quadraped can go bipedal so the
back legs take care of all locomotion, freeing the forelimbs to become wings.
Duplication of genes means the copy can evolve while the original keeps doing
whatever that gene was supposed to do. Several bones at the articulation of the
lower mandible and skull meant one could do the hinge thing, while others
drifted around and became part of the auditory apparatus.
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