Fossils and their surrounding matrix can provide insights into what our world looked like millions of years ago. Fossils of angiosperms, or flowering plants (which are the most common plants today), first appear in the fossil record about 140 million years ago. Based on the material in which these fossils are deposited, it is thought that early angiosperms must have been weedy, fast-growing shrubs and herbs found in highly disturbed riparian stream channels and crevasses.
Dana Royer from Wesleyan University, Connecticut, and colleagues wanted to see if aspects of a fossil plant's life history, such as its growth strategy, could be determined from its morphology rather than from the matrix in which it was deposited. Could this technique corroborate the idea that these ancient plants were fast-growing species? And, importantly, how common was this life history strategy for plants 100 Ma? The results of their research are published in the March issue of the American Journal of Botany (http://www.amjbot.org/cgi/content/full/97/3/438).
The authors first needed to assess whether aspects of leaf morphology in living plants today could accurately predict their life-history strategies. In previous research, Royer and colleagues had found that two simple measurementspetiole width and leaf areacould tell a lot about the ecophysiology of a plant. They found that the ratio of petiole width (squared) to leaf area is correlated to a leaf's dry mass per area.
"Leaf mass per area is a measure of the density or thickness of leaves, and it is strongly linked to how quickly a plant turns over its nutrient resources," Royer said. "Thin, cheaply built leaves (low leaf mass per area) are typically associated with plants with fast growth rates, and plants like these are usually most competitive in highly disturbed environments such as riparian corridors because their rapid growth
|Contact: Richard Hund|
American Journal of Botany