A siliceous potpourris of freshwater organisms from the Cretaceous through the Eocene with a focus on diatoms

Description: How old are freshwater diatoms? What were the earliest freshwater diatoms? What can we learn from the fossil record? Although work on these questions is ongoing and far from settled, I will present finding from four North American fossil localities ranging in age from 83 to 48 Ma, and all of which represent time periods when the Earth was much warmer that today and lacked polar ice. Special attention will be given to Aulacoseira, Eoseira, Ambistria, Fideliacyclus and a few early raphe-bearing genera, and the potential for using morphometrics to reconstruct past environmental conditions will be discussed. Lastly, I will give a glimpse of other co-occurring siliceous microbes found with the diatom remains, including synurophytes, testate amoebae, rotosphaerids, heliozoans and parphysomonads, and discuss one example of how the totality of fossil specimens can be used to infer past environments.

Target Audience: This talk is targeted for a general scientific audience with special emphasis on diatoms and the Cretaceous to Eocene time period, and anyone interested in fossil microbes.