"Everyone has shown evidence that life could exist on other planets. What evidence is there that tell us that life doesn't exist in space?"
-
A Comparative Study of Precambrian and Cambrian Terrestrially-Derived Organic Remains
PI: Strother, Paul
Palynology, the study of structurally preserved microscopic organic matter, provides a very useful method for the study of ancient ecosystems because this method can recover abundant direct remains of once-living organisms. Spores and cysts of both algal and embryophyte (true land plants) origin can directly trace the history of surface-dwelling subaerial and freshwater aquatic organisms. The proposed research will compare palynomorphs from terrestrial (an near-shore) rocks of Precambrian age with their counterparts from non-marine facies from lower Paleozoic rocks. This study will identify and characterize those components of lower Paleozoic (about 0.5 billion years ago) terrestrial ecosystems that were in existence around 1 billion years ago. This information will be crucial in resolving questions about the evolution of morphological characters leading up to the origin of land plants. There are no records of (macroscopic) plant axes from rocks older than middle Silurian. Yet, the spore record indicates that land plants (embryophytes) originated much earlier by middle Cambrian time, or perhaps earlier. By examining entire assemblages of diverse populations of spores and associated remains from non-marine sediments that clearly predate the origin of land plants, I hope to distinguish those components of the ancient subaerial and terrestrial aquatic flora that are more algal in character from those related to the evolving charophyte to embryophyte lineage. This will be the first study to examine in a comprehensive and comparative way, the nature of the evolving terrestrial (=subaerial and freshwater aquatic) landscape based on a direct microfossil proxy.
The proposed work involves field collection and chemical maceration of rock samples. The extracted microfossils will be characterized using transmitted light microscopy, scanning electron microscopy and transmitted electron microscopy.
An assessment of the development of non-marine ecosystems can help constrain geochemical (and other) models of planetary development that include atmosphere-organism interactions. In helping to document the water to land transition within the course of plant evolution on Earth, this proposal is relevant to the study of universal evolutionary processes that may apply to the evolution of life on planets in general. Research on Precambrian paleobiology is based largely on microfossils and geochemistry from marine sources rocks. This proposal represents an opportunity to add studies of microfossils that inhabited the Precambrian terrestrial landscape.
