Biol. 425 Midterm
Name
Section I. Matching (1 point each, 20 points total)
Match the terms on the right (by writing the corresponding letter or number on the lines provided)
with the short definitions or descriptions on the left. There may be more than one correct answer
per description, but only one correct answer is required for full credit. Any incorrect answers
will result in no credit for that question.
1. N
"Wastebasket taxon"
2. M Not found in living eutherians
3. 2
Possess a double mandibular condyle
4. H
All species"swim" through sand with
fore-aft movement of forelimbs
5. W,6 Possess a cloaca
6. B
Present in 'Menotyphla'
7. W Monotypic
8. P, I Possess palatal fenestrae
9. 9
Membrane connecting the hindfoot and (in
some cases) tail
10. S Old World fruit bats
11. E,H,I,P,S,W,X,1,4,7,10 Possess a complete
zygomatic arch
12. G The metatherian placenta
13. L 3% organic
14. Z Labial (or buccal) -most prominent cusp on
a lower tribosphenic molar
15. W,7. 1/2 credit for H
Sprawling posture
16. V, T Oldest metatherian fossils found here
17. (lots)Taxon of derived therapsids
18.X
Bone structure of endotherms
19. T The Age of Dinosaurs
20. N,Q Non-monophyletic
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.
M.
N.
O.
P.
Q.
R.
S.
T.
U.
V.
W.
X.
Y.
Z.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Afrotheria
Cecum
Cementum
Cenozoic
Chiroptera
Chorioallantoic
Choriovitelline
Chrysochloridae
Dermoptera
Duodenum
Embryonic diapause
Enamel
Epipubic bones
Insectivora
Lamellar-zonal
Scandentia
Lipotyphla
Madagascar
Megachiroptera
Mesozoic
Optic foramen
North America
Ornithorhynchidae
Fibro-lamellar
Paracone
Protoconid
Rodentia
Soricidae
South America
Talpidae
Tapetum lucidum
Tenrecidae
Plesiomorphy for Mammalia
Tragus
Uropatagium
Vespertilionidae
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Biol. 425 Midterm
Name
Section II. True of false ( 2 points each, 20 points total)
21.
T
F
Therapsids have the diapsid skull condition. SYNAPSID
22.
T
F
Paucituberculata is the only South American member of the
Australidelphia. MICROBIOTHERIA
23.
T
F
Most eutherians with only 3 upper premolars have lost P4
24.
T
F
Jaw articulation between the dentary and maxilla is a diagnostic
feature of living mammals
SQUAMOSAL
25.
T
F
All teeth in living mammals are diphyodont.
26.
T
F
The malleus in the inner ear of living mammals evolved from
the articular bone in the upper jaw of mammal-like reptiles. LOWER
27.
T
F
All diprotodont marsupials have syndactylous digits.
PAUCITUBERCULATA DOESN'T.
28.
T
F
Saltation (hopping) in kangaroos is more efficient than regular
quadrupedal locomoton at high speeds.
29.
T
F
The Paleocene came before the Oligocene.
30.
T
F
Phenetics groups organisms based on shared, derived features.
P1
MOLARS AREN'T!
Section III. Short answers (no more than a couple of sentences; 4 points each, 20 points
total).
31.
What is maximum parsimony and how is it used in phylogenetics?
Definition: the simplest explanation, requiring the fewest ad hoc assumptions, is the preferred
one. It is used in phylogenetics both to select among alternative trees (those requiring the fewest
'steps') and/or to interpret character evolution (e.g., the minimum number of times an individual
character has changed over time).
2 pts. for correct definition (1 pt. if partial definition or only "rule of simplicity"). 2 pts. for how
it's used in phylogenetics (either "prefer the tree with the fewest steps" and/or "study character
transformations". 1 pt. if only "least steps" or similarly brief answer.
32.
Why don't marsupials have fins, wings, or hooves?
As discussed in lecture and the textbook and seen in the Attenborough movie, neonatal
marsupials must use clawed forelimbs to climb from the vaginal opening to the nipples in their
mother's pouch. From your textbook: "This necessarily precludes the forelimbs from becoming
hooves, flippers, or wings."
2
Biol. 425 Midterm
33.
Name
Were some therapsids endothermic? Provide evidence in support of your answer and
why that evidence is compelling.
Almost certainly. The key concept here is that fossil evidence strongly suggests that
therapsids possessed maxillary turbinals, which are ONLY found in endothermic taxa and
ONLY function if body temperature is warmer than ambient temperature. Although we
discussed other lines of evidence, this was the clincher.
2 pts.) turbinals only found in extant endotherms and/or only work if internal T greater
than ambient T (or countercurrent heat exchange).
1 pt.) Evidence of turbinals found in some fossil therapsids
1 pt. if "hair"
34.
Based on your answer above, do you think cynodonts were endothermic? Why or why
not? (Hint: this is a tree-thinking question!)
Given the evidence that therapsids were endothermic, we can apply the principle of parsimony to
asnwer this question. If therapsids were endothermic, and we KNOW that mammals are
endothermic, then the most parsimonious explanation is that endothermy evolved once in the
common ancestor of therapsids and mammals. Because cynodonts share a more recent common
ancestor with mammals than they do with therapsids, we can infer that the common ancestor of
cynodonts+mammals was endothermic (otherwise, we have to consider additional "steps"
involving the gain or loss of endothermy). Although it's true that both therapsids and cynodonts
are paraphyletic, that isn't germane to this question. Finally, maxillary turbinal ridges have been
found on cynodont fossils (as well as more 'basal' therapsids).
If you answered #33 incorrectly but correctly applied that logic to answer this question, you were
given partial (and, one might therefore say, generous) credit.
2 pts: Yes
2 pts: correcty application of tree-thinking. 1 point if "basal condition" rather than a more
explicit/parsimony explanation.
CHANGE THIS QUESTION; AS PRESENTED, CYNODONTS ARE DEPICTED AS BEING
THE FOSSILS WITH EVIDENCE OF TURBINALS! NOT A TREE-THINKING QUESTION.
35.
Label each of the reproductive tracts below as either meta-, proto-, or eutherian. Circle the
term that represents a plesiomorphy not present in the other two figures.
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Biol. 425 Midterm
Metatherian
Name
Eutherian
Prototherian
Section IV. Fill in the blanks or circle the correct / incorrect option
(2 points each, 20 points total)
36.
Lower incisors grow out of the dentary _ bone, whereas upper cheekteeth grow out of the
__maxilla(ry) bone.
37.
Metatherian reproduction is characterized by short/long gestation and short/long
lactation.
38.
Hair develops from the invagination/evagination of the epidermis and is found in
most/all living mammals.
39.
Bergmann's/Huxley's Rule predicts that populations within a species should be largerbodied/smaller-bodied in warmer climates.
40.
Bats foraging in open habitats tend to have high/low aspect ratios, with
long and narrow/short and broad wings.
41.
Members of the order Carnivora have evolved an efficient shearing mechanism between
upper _____P4_
_ and lower _____m1_
_.
Partial credit given if only "premolars" and "molars" (respectively) was written.
42.
Kangaroo reproduction is characterized by a process termed (2 words)
______embryonic diapause ____
_, whereby a female kangaroo may have up to
________3
_ young dependent on her at one time.
43.
Insectivorous mammals tend to have teeth with shearing surfaces resulting from crests
connecting either two cusps (styles) on the stylar shelf with the paracone in the
________zalambdodont
_ molar cusp pattern or three cusps on the stylar shelf with
both the paracone and metacone in the _______dilambdodont
_ molar cusp pattern.
44.
All living mammals possess a double
articulates with the dual facets of the axis/atlas.
45.
The skeleton of living mammals is considered to be more simplified/complex than that
of reptiles and extinct reptile-like mammals and is also characterized by
indeterminate/determinate growth.
, which
4
Biol. 425 Midterm
Name
Section V. Short essay questions (confine your answer to the space provided; be concise but
complete. 10 points each).
41. List the families (taxonomic, not common, names) formerly placed in the Order Lipotyphla (1 pt.
each). Based on recent molecular phylogenetic evidence, is it appropriate to consider "lipotyphlans" as
representative of the common ancestor of eutherian mammals? Why or why not? (4 pts.)
1 point each for the correct (or phonetically similar) spelling of the six families: Tenrecidae, Soricidae,
Erinaceidae, Chrysochloridae, Solenodontidae, and Talpidae. 1 pt. off for each INCORRECT answer, even
if all 6 correct families were also listed.
4 pts. for answering "no" and providing an answer based on current phylogenetic hypotheses and/or modern
reasoning.
Traditional morphology-based hypotheses typically placed a monophyletic Lipotyphla basal to the
remaining eutherian orders. Because of this, and the observation that lipotyphlans lacked any striking
anatomical apomorphies, they were considered to be extant, plesiomorphic representatives of the common
ancestor of eutherian mammals. Recent molecular evidence suggests that the Order Lipotyphla is nonmonophyletic (polyphyletic, in this case), with Tenrecidae and Chrysochloridae recovered in a clade of
African mammals (Afrotheria) and the remaining four families recovered in a clade of predominantly
northern or Laurasian taxa (Laurasiatheria). Because each clade of "lipotyphlan" families (Afrosoricida in
Afrotheria, Eulipotyphla in Laurasiatheria) is more closely related to extremely derived orders than to each
other, there is no compelling phylogenetic argument that they represent the MRCA of Eutheria. If
Afrosoricida was supported as basal to all other afrotherian orders AND Eulipotphyla was supported as
basal to all other laurasiatherian orders, this might suggest that each of these major clades (Laurasiatheria
and Afrotheria) descended from an insectivore-like common ancestor, but both Afrosoricida and
Eulipotyphla are recovered as nested within, rather than basal to, Afrotheria and Laurasiatheria,
respectively. This was a difficult question and was graded accordingly, but the key concepts are (1)
"Lipotyphla" is not monophyletic and (2) neither Afrosoricida nor Eulipotyphla are basal to other
eutherians. Several people also commented on the fact that there are several synapomorphies present in
living "lipotyphlan" families, which is true.
42. Briefly define the three models of eutherian mammal diversification (hint: the 'fuse' analogy)(2 pts.
each). Which model(s) is supported by molecular evidence (1 pt.), and which is supported by
paleontological evidence (1 pt)? Why do we care (2 pts.)?
Explosive model: all orders diversify at or around the K/T boundary.
Short fuse: Most orders originate & diversify BEFORE K/T boundary
5
Biol. 425 Midterm
Name
Long fuse: Orders originate BEFORE but don't diversiby until AFTER the K/T boundary.
Short fuse supported by molecular evidence (1/2 pt. if long fuse).
Paleontological evidence: explosive, traditionally. Long fuse more recently.
Extra credit question 1 (2 points): What is the taxonomic rank (e.g., Kingdom,
Phylum, Class,...species) of the recently discovered mammal family Laonestidae?
No, this was not a trick question, and the answer was provided twice in the question
itself. Recall that one of the relatively few rules in mammalian taxonomy is that family
names end with the suffix "-dae" (pronounced "dee," not "day"). Also, you are told this
is a family!
Extra credit question 2 (2 points): What is the order of the five Cenozoic epochs,
beginning with the oldest? [FIX THIS; THERE ARE 5 IN THE TERTIARY, BUT 7 IN
THE ENTIRE CENOZOIC]
6