Topic: SOES/NOC Online Seminar Series
Time: Oct 6, 2020 2:00 PM London
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Speaker: Daniel Conley, Lund University
Perspectives on the Evolution of Diatoms
Although molecular clocks suggest that diatoms evolved over 200 Ma ago, this result has been largely ignored because of the lack of diatoms in the geologic fossil record. Most studies focused on diversification during the mid-Cenozoic 30 Ma ago where abundant diatom fossils are found. Much of the older fossil evidence has likely been destroyed by dissolution during diagenesis, subducted or is concealed deep within the Earth. In DEVOCEAN we are searching for evidence on diatom evolution and speciation in the geological record by examining formations representing locations in which diatoms are likely to have accumulated in ocean sediments. We are also investigating the timing and magnitude of dissolved Si drawdown following the origin of diatoms using the isotopic silicon composition of fossil sponge spicules and radiolarians. The project will also provide new insights into the timing of dissolved Si drawdown and other key events, which reorganized the distribution of carbon and nutrients in seawater, changing energy flows and productivity in the biological communities of the ancient oceans.