DISSERTATION RESEARCH: Structure and Systematics of the Earliest Terrestrial Ground Cover

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A grant has been awarded to Dr. Gar Rothwell and Mr. Alexandru Tomescu at Ohio University to study the organisms that formed the earliest known terrestrial groundcover. Fossils of these organisms collected by the grantees in 445-435 million year old rocks of eastern North America (Virginia, Pennsylvania) represent the oldest unequivocal evidence for life on continents, out of the marine realm. The goal of their project is to characterize the structure of these early terrestrial organisms, and to clarify their biological relationships. To do this, they will isolate fossils from the rocks, prepare them, and investigate their structure employing light- and electron microscopy. They will then compare the fossil organisms to living groups, to clarify their biological and evolutionary relationships. Although the origin of life on land over 450 million years ago has been the subject of considerable research and much speculation, the nature of the earliest terrestrial organisms still ranks among the most crucial unanswered questions in modern life sciences. By investigating newly found fossils of the earliest terrestrial organisms, this project can address these questions, strongly impacting thinking and working hypotheses in evolutionary biology and earth sciences. By identifying the groups of organisms that were the first to colonize the continents, this work will provide much-needed direct evidence for the ancestors of early terrestrial colonizers, and for the initial patterns of evolution and diversification of life on land. Characterizing the first abundant land organisms also has important implications for global-scale interpretations of weathering process changes that resulted from the origin of terrestrial groundcover, and for the impact of these changes on continent-ocean chemical cycles.