Geosciences 308
First exam
Fall 2004
Name___________________________
Part I. Write out the geologic time scale. Include the eras, the periods, the epochs of
the Cenozoic, the ages of the boundaries between the eras, and the age of the earth.
Use the back of this page if necessary. (5 points, no partial credit).
Part II. Answer seven of the following eleven questions (Each is worth five points).
1. Distinguish between the disarticulation and fragmentation of skeletal remains. Give
an example of each.
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2. This species of trilobite is characterized by (choose all the correct answers).
a. growth by accretion
b. growth by modification
c. determinate growth
d. indeterminate growth
e. growth by molting
f. growth by addition of new
parts
3. Name (the formal name) and give an example (common name OK) of five of the six
kingdoms.
4. Place the following in order, from oldest to youngest (be sure to indicate which is
oldest and which is youngest).
First fossil eucaryotic cell
Abundant stromatolites
Vendian
First fossil metazoan
First fossil prokaryotic cell
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5. Give an example of a body fossil, a trace fossil and a molecular (or chemical) fossil.
6. Briefly describe two ways in which the ontogenetic age of a fossil specimen can be
estimated. Be sure to note if the age estimate is quantitative or qualitative.
7. Briefly describe two reasons why individuals of the same species might differ in size
or shape.
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8. Based on the cladogram below, answer the following questions:
a. which pair(s) of species is (are) most closely related to each other?_______
b. Which character(s) is (are) primitive (ancestral) for all six species?________
c. Which character(s) is (are) present in species C?____________
d. Which characters are shared by species E and F?____________
A
B
C
D
E
F
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5
4
3
2
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9. What is the difference between an attritional, or “time-averaged” assemblage of
fossils and a catastrophic assemblage of fossils?
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10. Place the following in their correct temporal sequence. Be sure to indicate which is
oldest and which is youngest.
Apex chert
Isua Formation
Ediacara fauna
Banded Iron Formations
Small shelly fossils
11. Give an example (common name is OK) of each of the following:
(a) heterotrophic metazoan
(b) anerobic prokaryote
Part III. Answer three of the following four questions (each is worth 10 points).
1. Sketch a graph that shows how the number of families of marine fossils changes
during the Phanerozoic. Be sure that your graph extends from the Vendian to
the Holocene and shows the approximate location of the Permian/Triassic and
the Cretaceous/Tertiary boundaries. Indicate the scale of the axis that shows the
number of families.
What evidence might suggest that this pattern is the result of sampling rather
than evolution?
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2. You’ve just returned from collecting Cenozoic mammal fossils in the badlands of
New Jersey. You only found one complete, articulated (all the bones still together)
specimen of a giant rodent, Rattus mechami. The specimen has one skull, 70 vertebrae
and 30 ribs. All the other bones you found were disarticulated and isolated from each
other. You found 6 skulls, 780 vertebrae and 60 ribs. Based on this information,
(a) What is the minimum number of individuals needed to result in this collection of
disarticulated and isolated bones?
(b) How did you estimate this number?
(c) What is the maximum number of individuals needed to result in this collection of
disarticulated and isolated bones?
(d) How did you estimate this number?
(e) Rank the three bone types in order from most likely to be preserved to least
likely to be preserved. Be sure to indicate which is most likely and which is least
likely.
(f) Justify your rankings.
3. Joe Blotz, with financial support from the McDonald’s Corporation, had another
successful season of collecting dinosaurs in the Gobi desert. In his opinion, one of the
skulls found by Dashzeveg Bator (a local goat herder he hired) is a new species of
Apatosaurus, What must his species description include, where will he likely publish the
description, and what species name can he give the new discovery?
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4. Shown below are measurements you made on a Devonian clam shell that you
discovered during your last field season in northern Arizona. The estimate of age is
based on the prominent growth lines, which you interpret as marking winters.
Age
(years)
1
3
4
6
8
11
14
Length
(mm)
1
3
4
5
6
7
8
Width
(mm)
1
3
5
7
10
14
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a) Draw a graph that shows the absolute rate of growth
of the shell’s length. Label the graph and label the
axes
b) Draw a graph that shows the relative growth of
length and width. Label the graph and label the
axes.
c) Is absolute growth determinate or indeterminate?
d) Is the relative growth isometric or allometric?
Part IV Answer one of the following two questions (30 points).
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1. Discuss how the evolution of Precambrian life affected the Earth’s environment, and
how, in turn, those environmental effects may have affected the evolution of
Precambrian life. Your answer should discuss the timing and sequence of key biotic
and environmental events and should include examples of the evidence for them.
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2. Potential fossils can be destroyed and/or they can be displaced from their original
position in time or place. Suppose that you have a collection of fossils in front of you.
Discuss, using examples wherever possible, how you might detect the effects of the
different types of destruction and the different types of displacement (confusion). What
features of the fossils or rocks would you examine?
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