The proposed project concerns the collection, description and study of microscopic plant remains and acritarchs from Silurian age rocks in northeastern North America. The principal section to be sampled will be the Arisaig Group in Nova Scotia, an extremely well-studied shallow marine deposit which spans the entire Silurian Period. Spores and other plant fragments occur as organic components of these near-shore marine deposits, and, because organic-walled phytoplankton (acritarchs) are mixed in with land plant remains, it will be possible to compare the North American assemblages directly with their counterparts from the type sections in the Welsh Borderlands and the Prague Basin. Since palynomorphs represent the remains of primary producers in both the terrestrial and marine realm, the reconstruction of palynomorph assemblages should serve as an index of the basal trophic resource for benthic marine communities. PI will compare palynomorph diversity and assemblage dynamics at both micro-and macro-scales with previously documented paleoecological and benthic community reconstructions for the Arisaig section. PI will also test for correlations between benthic invertebrate community assemblages and syndepositional phytoplankton assemblages. The documentation of the non-marine component of the Arisaig Group will represent the first attempt to study the primordial adaptive radiation of the land plants from a single continuous Silurian section. By establishing a stratigraphic record of fossil plant remains, the information generated from this project will be critical to the serious study of the origin and early evolution of the terrestrial plant kingdom.
