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Monte Garroutte, Jordan Metzgar, & Hirotsugi Mori (UA Fairbanks)
Our module will include a hands-on lab activity focusing on comparing and contrasting fossil plant specimens and modern plant specimens. Fossil plants will be examined by preparing coal ball peels from the Pennsylvanian Epoch (318.1 to 299 mya, Upper Carboniferous) coal balls collected in Ohio. Coal balls are exceptionally preserved calcareous permineralized peat specimens from Carboniferous coal swamp forests. When the specimens were first described, the majority was from coal seams and composed of spherical or ovoid limestone rocks leading to the name “coal ball”. Large collections have been assembled from southern Illinois, Kentucky, Ohio, Kansas, and Iowa, as well as Great Britain, Belgium, France, and other localities in Europe (Steward & Rothwell, 1993). Coal swamps are mires, wet environments where organic material accumulates. Coal balls provide the most direct evidence of the original swamp community and of the botanical composition of the coal bed. An easy and inexpensive protocol for making coal ball peels developed by a colleague will be used. A flash movie on the coal ball activity is available courtesy of the University of Alberta http://www.biology.ualberta.ca/facilities/multimedia/uploads/botany/peel1.swf
Coal ball peels are similar to cross-sections of fresh plant material and can reveal anatomical and morphological traits of the fossil plant. A coal ball generally contains a large number of different plant groups and organ types and allows for quantification of the botanical diversity in the Carboniferous coal swamp. Comparison between different coal ball localities furthermore allows for inference of different climatic conditions as reflect by the associated plants found in the coal ball, which is often specific to a collecting locality. Specimens of modern representatives of the same lineages from the University of Alaska Museum Herbarium will be used to show present day appearance of these plants. Collections data in Arctos will be used to demonstrate the present day ranges of some of the extant descendants of the fossil lineages.
An additional inexpensive lab activity will also be used to help students make the connection how plants are assembled in the rock matrix and what importance plane of section plays. A matrix of jello and leaves/ stems will be sliced into thin sections to illustrate how coal ball fossils are formed and how our peels relate to living plants and the angle at which you cut the coal ball.
Specific questions for students are:
1) What is biodiversity, why is is important, how can it be assessed?
2) How does the coal ball method of assessing biodiversity compare to other methods?
3) Why have the fossil lineages changed so dramatically in stature, appearance and abundance in the present day?
4) How has climate influenced these changes in the long term and how is anthropogenic climate affecting the present day distribution of these plants?
5) What uses are there for fossil plants or museum specimens?
Further reading:
Scott, A.C. and G. Rex. 1985. The Formation and significance of Carboniferous coal balls.
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, Vol. 311, No. 1148: 123-137.
Steward, W.N. and G.W. Rothwell. 1993. Paleobotany and the Evolution of Plants. 2nd
edition. Cambridge University Press, New York.
