Download Exploring the Fossil Record-Teacher Version Highlighted areas are

Exploring the Fossil Record-Teacher Version
Highlighted areas are teacher tips and examples- See instructional plan for more details
Our world is the world we see with our naked eyes, and that is what we use for our everyday measuring stick (Bonner
2006). But is the world exactly as it has always been? Is our perception of what we see correct? Size is relative to your
perception, small versus big depends upon what you are comparing it against. To humans, an elephant is large; to a
bacterium the area on a petri dish is large. How can size influence an organism’s ability to survive? Through the fossil
record we can examine changes in body size of organisms.
What other evidence can we determine/gather through looking at the fossil record? (list at least 2 other ideas)
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In this lab you will use the fossil record to explore body size, biological diversity, speciation, and mass extinction as a
function of environmental variations and independently through time. Life started in the ocean, therefore our longest
lineages of species with data in the fossil record comes from marine organisms. Using collected data and available
databases, you will analyze changes in body size and diversity over time.
Part 1: Gastropod Body Size through time
1. Create a data table in your lab notebook to collect the following data on fossil images of marine gastropods
(snails): Figure Measured, Age, Genus, Subgenus, Species, Subspecies, Height, Width, Magnification,
Biovolume, and Log Biovolume. The last two will be calculated later.
2. At each lab station you should find the following: Sample Gastropod Fossil Images, Description of Information
sheet, Geologic time scale and Rulers/Calipers. (See attachments #3-5)
3. For each gastropod measured, record all the information can from the description. Determine the height (in
relation to the coiling axis) and the width (perpendicular to the coiling axis) to the nearest mm (if using a ruler) or
nearest hundredth of a mm (2 decimal places, if using calipers).
Ex:
Height measured by coiling axis of snail shell,
Width is perpendicular to coiling axis,
tallest points inclusive
widest parts of shell inclusive
4. Measure at least 10 different species, ideally from as many different time Period’s (Cambrian, Ordovician, etc.)
possible.
5. Calculate Biovolume using the formula for a cone (see Description of Information sheet-Attachment#4). Don’t
forget to take into account the magnification in the calculations.
On the excel or Google Doc…
Volume cell formula should be
=(PI()*((H2/I2)^2)*(G2/I2))/12
with H2 being the cell with width, I2 as the cell with magnification, and G2 as the cell with height.
Log volume formula:
=LOG10(J2)
with J2 as the cell with calculated volume.
Part 1: Gastropod Body Size Analyses- Complete and include answers in lab notebook
1. Create a graph of Log Biovolume versus Time for the provided Gastropod Database and include a trendline.
2.
3.
4.
5.
Example:
What type of graph did you choose to display the data (line, bar, X-Y scatter, etc.) and why? What type of
trendline did you choose and why?
X-Y Scatter, data is not continuous, log trendline as data is graphed as log base
What are some advantages for graphing the Log Biovolume as opposed to regular volume on these graphs?
Data is so spread out that graphing Log volume allows for better interpretation. Small differences in volume, ie
less than an order of magnitude are not necessary for resolution and observation of trend, therefore log graph is
best choice to mitigate sampling biases. Variations on answer suitable.
Compare/Contrast the difference from data collected in class with the larger provided Gastropod Database.
Discuss validity and confidence of the data between the two data sets and why the graph was made from the
Database.
More data gives more validity and confidence to data, variations on answer suitable.
Using the Gastropod Database graph, discuss trends in the data. What inferences/observations can be made from
the graph? How does this potentially relate to body size?
Over time body size decreasing, possibly more predation pressure as number of different types of species would
be increasing over time. Various answers suitable.
Part 2: Diversity and Extinctions in the Fossil Record
1. Go to online Marine Fauna Database (aka Sepkoski database) at http://strata.geology.wisc.edu/jack/start.php.
Obtain data for all marine fauna. Under the drop down menu for “Choose Fauna,” select “All Genera.” Scroll to
the bottom of the screen (do not select anything else) and click submit.
2. Copy and paste all of the data into an excel spreadsheet. Delete all columns of data except: stage, date, and Total
D. (See attachment # 8-sheet 1(all genera) and sheet 2 (total d vs. time) and below for what it will look like)
Part 2: Diversity and Extinctions Analyses- Complete and include answers in lab notebook.
1. What do stage, data, and Total D represent in the data you collected?
2. Create a graph representing All Marine Genera through time. Be sure to include all units and label properly.
Example:
3. Create a graph of a minimum of two other phyla or class of marine organisms through time. **Please note, when
choosing any class (not so for phyla), an error occurs on the data table. The date column is repeated twice. The
“Total D” data is actually found under the label “q Lmy”. Make sure you adjust your data table
accordingly.**Also remember the Sepkoski database is only marine organisms.**
Example:
4. What type of graph did you choose to display the data (line, bar, X-Y scatter, etc.) and why?
XY Scatter-similar reasons stated above
5. Compare/Contrast your all marine genera graph to that of the mass extinction graph in your textbook and
discussed in class. Does it follow the same trends? Why or why not?
Similar….answers will vary.
6. What do the peaks in each graph mean? What do the valleys mean? At what time periods do these occur?
In our graph peaks mean high diversity, lots of genera. Valleys mean loss of diversity, fewer numbers of genera.
Deep valleys would signifiy mass extinction time periods, etc.
7. What inferences/observations can be made from each of the graphs with regards to mass extinctions, speciation,
and diversity over time?
Answers will vary but should be clear explanations and include appropriate vocabulary.
Part 3: Diversity, Body Size, and Environmental Covariates- Analyses
1. Organisms body size, episodic speciation, mass extinctions, and other factors are often influenced by
environmental factors. These are often referred to as covariates, something that may be predictive of an outcome
or be an interacting variable. Browse through the provided environmental covariate database, Sepkoski’s online
Marine fauna database, and/or the Gastropod database; think about how different aspects of the environment may
influence biology. (See attachments#6-7, delete graphs within provided databases-meant only as a guide for
teacher as to what to expect)
2. Create a graph of atmospheric oxygen over time. (Using attachment #7)
Example:
3. What would you expect to see in the oxygen gas graph, relate this to what you learned about the history of earth
and life on earth. What are some limitations to the graph you created?
Little or no oxygen to start until organisms that produced it and built up in atmosphere. Peak and then drop due to
organisms taking advantage of it, answers will vary. Should display knowledge of previous concepts in class.
4. List a minimum of two (three preferred) interactions amongst all of the databases provided to you that you will
explore. (for example, oxygen levels and total marine genera diversity through time)
a. Will vary
b.
c.
(optional)
5. Based on your knowledge of evolution, an organism’s needs to sustain life, and explorations undertaken in this
lab; what are your hypotheses regarding the interactions listed above? Will vary
6. Based upon what previous evidence do you base your hypotheses? Will vary
7. Create two different graphs of the interactions you listed above. Be sure to label axes (including secondary axes)
with proper units and titles.
Example:
8. Discuss your observations/inferences of the graphs you created. Do they support or refute your hypotheses? If it
refutes your hypotheses, can you think of another explanation? What general trends do you observe? Do they
have negative, positive, or no correlations with one another? Why or why not? What are some limitations to the
inferences/correlations that can be made? Be sure to use evolutionary related terms in your analyses of data.
(Read: Raup et al. 1982 and Payne et al. 2009 to supplement your discussion and analyses of data, be sure to cite
properly)
Answers will vary greatly but should encompass information about the environment and its role in evolution.
Ability to correlate data, strengths and weaknesses of that, etc. and appropriate vocabulary and reference citations
should be included.
Bibliography
Payne, Jonathan L., Alison G. Boyer, Felisha A. Smith, Jenifer A. Stempien, Steve C. Wang, James H. Brown, Seth
Finnegan, Michal Kowalewski, Richard A. Krause Jr., S. Kathleen Lyons, Craig R. McClain, Daniel W. McShea, and
Philip M. Novack-Gottshall. "Two-phase increase in the maximum size of life over 3.5 billion years reflects biological
innovation and environmental opportunity." Proceedings of the National Academy of Sciences 106.1 (2009): 24-27.
Print. (see attachment #9)
Raup, David M., and J. John Sepkoski. "Mass Extinctions in the Marine Fossil Record." Science 215 (1982): 1501-1503.
Print. (see attachment #10)
A lower level article can be used for differentiation. (see attachment #11)