Final 1: Freeing Our Brachiopod Brothers

Materials and Methods

To successfully complete our project it was essential to experience the fossils in their natural surroundings and gather them ourselves. The fossil formations near Brookville, Indiana were studied on Sunday, October 3rd and October 17th . The road cut exposes the Ordovician bedrock that served as our sample gathering location. We also collected samples from the roadside of Highway 1 outside Brookeville, Indiana on October 17th and December 4th. Photographs were taken of the fossils contained within the strata in the different formations. These pictures are located on the web site and were used as a teaching aid for our discovery lab.
After we brought the samples back from Indiana, we spent the next week unsuccessfully trying to identify and categorize our fossils. First, we tried to organize them by genus using the books and guides provided to us by Hays and Mr. Merak, but we still could not identify them. In light of this, we took our fossils to the Limper Geology Museum, on October 26th, to enlist the help of Mr. Merak on developing a key for identifying and organizing our finds. With the assistance of Mr. Merak we have become apt at identifying the different genuses.
Some basic tools were used in the examination process of our experiment. We utilized a hammer and various dentistry tools to excavate the fossils from the limestone. Furthermore, we have utilized a magnifying glass to examine the fine details of the brachiopods. Jenny's camera and film were used to document the locations we gathered fossils from. Finally the Internet has played an integral part in helping us both display our work and link to the work of other fossil collectors and institutions. Through working on our own and with Mr. Merak, we were able to identify the genuses of many of the Brachiopods collected.
Using our knowledge of the characteristics of the different genuses and our photographs, we asked the class to help us identify some of our brachiopod finds as our Discovery Lab. This Discovery Lab commenced with a brief overview of the Ordovician period using the Internet to aid us in the visual presentation. We discussed the difficulties of working with the fossil record in general, and the challenges we encountered therein. Then the class was divided into four groups with one of us leading each group to ensure accuracy of identification. Each group examined different layers or a different site from our fossil gathering expeditions. Our newfound knowledge of identification was utilized to aid in this process, teaching the terminology for identifying the characteristics as we went. The Discovery Lab concluded with the class collaborating on the different characteristics of the various genuses that they identified. This observation of how the brachiopods differ in the various aspects of their anatomy helped to give the class a better understanding of the evolutionary process and an appreciation for the complex and time consuming work of paleontologists.
We feel that our lab is sound because we have consulted with Hays and Mr. Merak (the curator at the geology museum) about the details of our experiment and research. Prior research and documentation has ensured that the brachiopods are indeed from different layers. No statistical analysis was done during the Discovery Lab, since just identifying the fossils encompassed the entire class period. We are confident that our experimental design was adequate for our goals of inciting interest in the fossil record and in the evolution of the different organisms that constitute life on earth.
Our lab timeline was limited to the weekends, since we inevitably got lost for at least four hours on two of the three excursions. First, a proposal for the project was devised on the thirtieth day of September in the year 1999. Secondly, we set out on October 6, 1999 to collect fossils from the formation near Liberty, Indiana on the Fairfield Causeway and from the formation near Brookville, Indiana on Highway 101. We returned to the outlying area of Brookville, Indiana on October 17, 1999 and December 4, 1999 to collect fossils from the formation on Highway 1. On October 26th, we visited Mr. Merak at the Limpier Geology Museum to develop our taxonomic key. During class on November 15th, we presented our project and laboratory packet to the class and gave overview of the Ordovician period and our project in general. The final presentation of our results was completed and presented to the class on December 9, 1999.

Results

Relative Abundance Comparison
-Within and Between Strata
-# Individuals of a Species/Total Number of Individuals
Similarity Test
-S=C*2/Sum # of Species in the two strata combined
-Used to compare species composition of strata in terms of the number of species present and the number of species in common.

Relative Fossil Abundance Per Stratum

Abundance of Fossils Within Different Strata

Similarity Test Results Graphs

Conclusion

Darwin was right! Sure evolution might be a fact in the scientific community, but we had to test out this theory in our backyard. While we merely attempt to show diversity between the strata, not the causes of the diversity, our findings seem to confirm the theory of evolution. Our
results have shown differences not only in the number of individuals per stratum, but also in the range of species throughout the different strata. The similarity tests confirmed our expectations that the closer the samples to each other the more similar they were. The extreme drop
in the almost 60 % relative abundance of Rafinesquina from stratum D and decline through the strata to less than 5% relative abundance in stratum A, suggests that the Rafinesquina population suffered great losses. Rafinesquina disappear entirely in stratum B, only to reappear (though
in small numbers in stratum A). We believe this is because our sampling technique was not comprehensive enough, not that the Rafinesquina were whisked away for some million years only to reappear in the fossil record later.
We noted that Rafinesquina are the largest local brachiopods and wondered if that had to do with their decline. We looked at our data to see if larger species started to fare worse as time progressed. Leptaena, medium sized brachiopods with concentric rings on their shell, were of
the highest relative abundance in stratum C, but disappear in stratum B. Strophomena, which are only slightly smaller than Rafinesquina, dominate stratum B which does not validate our theory that perhaps smaller species would be more abundant in the younger strata.
Overall, baby Strophomena had the greatest relative abundance with Strophomena coming next suggesting that Strophomena were well adapted to their environment even over a long passage of time. We found that baby Strophomena dominated their samples, when they were found. In sample A6, 56 individual baby Strophomena were identified with only a single Rhynochotrema to keep them company. We see this again as 29 individual baby Strophomena and 6 adult Strophomena shared sample B4. We hypothesize that the premature Strophomena may have been more vulnerable to environmental changes than other Brachiopod species.
While we did not do sufficient research to affirm or negate these observations, they are an interesting start towards further study. The most lasting impression this project has made on us is a greater appreciation of scientific inquiry and experimental design. When we read our first hypothesis we can not help, but feel chagrin for the impossible scope of our design. Yet, we still went from being unable to even identify the genus of a Brachiopod to having a comfortable familiarity with the valve structure of Rafinesquina. The more we learned the more aware of our ignorance we became. Our greatest satisfaction is that our questions continue to become more sophisticated, even if our evidence hasn't banished the Jerry Falwell's of the world.

Literature Sited

Benton, M.J. "Analyzing Diversification Through Time: Reply to Sepkoski and
Miller." Trends in Ecology and Evolution. 1998: 201.
Caster, Kenneth, Dalve Elizabeth, and John Pope. Elementary Guide to the Fossils and
Strata of the Ordivician in the Vicinity of Cincinnati, Ohio. Cincinnati, Ohio:
Cincinnati Museum of Natural History. 1961.
Falls of the Ohio. 1999. "Ancient Shells at the Falls of the Ohio." (Files posted on the
World Wide Web). Retrieved September 9, 1999 form the World Wide Web: Falls of
the Ohio Home Page.
Feldmann, Rodney. Fossils of Ohio. Columbus, Ohio: Department of Natural Resources.
1996.
Hadly, Elizabeth. "Fidelity of Terrestrial Vertebrate Fossils to a Modern Ecosystem."
Palaeogeography, Palaeoclimatology, Palaeoecology. 1999: 389-409.
Hansen, Michael. (1994, October). "Geofacts" (Files posted on the World Wide Web).
Retrieved September 1, 1999 from the World Wide Web: Ohio Geological Survey
Home Page
Larsen, Glen. (1998, January). GEOFACTS (Files posted on the World Wide Web).
Retrieved September 9, 1999 from the World Wide Web: Ohio Geological Survey
Home Page
Marek, Joe. Personal Interview. 26, October 1999.
Raff, R.A. "Creating the Animal Planet." Trends in Ecology & Evolution. 1999: 39.
Rocque, Aurele. and Mildred F. Marple. Ohio Fossils. Columbus, Ohio: State of Ohio
Department of Natural Resources Division of Geological Survey, 1987.
Sepkoski, J. & Miller, A. "Analysing Diversification Through Time." Trends in Ecology
& Evolution, 1999: 158-159

Appendices

For all additional information such as an overview of Ordivician history and diagrams of brachiopod anatomy please visit our web site: http://www.muohio.edu/~mccartkp

For Further Info on this Topic, Check out this WWW Site: http://www.muohio.edu/~McCartKP . Next Article
Previous Article
Return to the Topic Menu

Here is a list of responses that have been posted to this Study...

Respond to this Submission!

IMPORTANT: For each Response, make sure the title of the response is different than previous titles shown above!

Visit the rest of the site!