NADS 2019 Meeting: Submit Abstracts
The deadline for abstract submission has been extended! The new abstract deadline is May 31, 2019!!! Email your abstracts to Kalina Manoylov. All abstracts will be peer reviewed by a member of the Scientific Committee (Becky Bixby, Paula Furey, and Jeff Johansen).
- include your affiliation and those of your co-authors,
- the preferred presentation style (Oral or Poster),
- underline the name of the presenting author,
- use 12 point Times New Roman font,
- capitalize the title,
- use a maximum of 350 words,
- use the example abstract as a guide.
THREE EXTANT GENERA OF FRESHWATER THALASSIOSIROID DIATOMS FROM MIDDLE EOCENE SEDIMENTS IN NORTHERN CANADA
Alexander P. Wolfe1 and Peter A. Siver2
1Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada
2Botany Department, Connecticut College, New London, Connecticut 06320 USA
The evolutionary history of diatoms is only constrained partially by the fossil record. The timing of several key events, such as initial colonization of freshwater habitats by marine taxa, remains poorly resolved. Numerous specimens of the genera Cyclotella, Discostella, and Puncticulata (Ochrophyta: Thalassiosirales) have been recovered in Middle Eocene lacustrine sediments from the Giraffe Pipe locality in the Northwest Territories, Canada. These diatoms extend the fossil record of the family Stephanodiscaceae to at least 40 million years before present (Ma) and thus provide a new evolutionary milepost for the thalassiosiroid diatoms, an important clade of centric diatoms with global representation in both marine and freshwater environments. The quality of the fossil material enables detailed investigations of areolae, fultoportulae, and rimoportulae, revealing direct morphological affinities with a number of extant taxa. These observations extend the antiquity of several characters of phylogenetic importance within the thalassiosiroid diatoms, including the fultoportula, and imply that the entire lineage is considerably older than prior constraints from the fossil record, as suggested independently by several recent molecular phylogenies.
Special Session - Those wonderful Thalassiosiras