Ecologic and evolutionary controls on shallow- marine ichnofaunas

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Ichnology involves the study of biogenic structures that result from the interactions between organisms and the substrate. Comparisons of ichnofaunas through geologic time reveal a complex interplay of ecologic and evolutionary controls. The different tracemakers and their specific responses to environmental changes reflect long-term macroevolutionary processes. Although ecologic controls have been the focus of ichnologic research, evolutionary aspects have been less explored. In particular, archetypal ichnofacies (distinctive suites of trace fossils), albeit recurrent in space and time, reflect changes through geologic time as a result of paleoecologic breakthroughs. The aim of this project is: (1) to compare marine ichnofacies through geologic time in terms of taxonomic composition, ecologic significance, and potential tracemakers, and (2) to discuss how faunal turnovers, degree of infaunalization, and colonization histories change the nature of archetypal ichnofacies during the Phanerozoic. The activities planned include: (1) fieldwork in several marine successions of different age, and (2) construction of a database of marine ichnofacies. To a lesser extent, the project will involve revision of trace fossil collections as supplementary information. Ichnologic information has been obtained from a number of stratigraphic units, spanning the Cambrian to the Neogene. These include the early Paleozoic of Argentina, Bolivia, Canada and Jordan, the late Paleozoic of Argentina, Brazil, England and United States, the Mesozoic of Argentina, Australia, Romania and United States, and the Cenozoic of Argentina, Chile, Venezuela and Romania. Additional fieldwork is focused on both critical intervals from a macroevolutionary perspective (Cambrian, Ordovician) and times with sparse ichnologic information (e.g. Devonian, Paleogene) . The database will be constructed based on critical examination of the literature, trace fossil specimens and field data. The database will include ichnotaxonomic composition, preservation styles, ethology, feeding strategies, tiering structure, ichnoguild assessment, age, and depositional environment.