Ordovician palynology: balance and future prospects at the beginning of the third millennium

Ordovician palynologic studies started in the 1930s when Eisenack first des cribed Palaeozoic "hystrichospheres" (later named acritarchs), and defined the chitinozoans and melanosclerites. During the ensuing two decades, Ordov ician palynologic investigations were mostly descriptive. It was the rise o f the oil industry in the 1950s and 1960s, which accelerated palynologic re search, particularly with the recognition that acritarchs and chitinozoans were biostratigraphically important groups for Ordovician stratigraphy. Tod ay, more than 700 publications deal with Ordovician acritarchs, and about 4 00 papers concern Ordovician chitinozoans. In addition to these two palynom orph groups, other less important organic-walled microorganisms have been s tudied, These include plant remains (spores, cuticles): scolecodonts and su ch enigmatic groups as the melanosclerites and the mazuelloids, This paper summarises the research on Ordovician palynomorphs during the 20th century and looks ahead to the types of research that may be important and most fru itful for Ordovician palynology at the beginning of the new millenium. Part icular attention is paid to the C.I.M.P./I.G.C.P, no. 410 joint meeting "Or dovician Palynology and Palaeobotany," held in Prague during the 8th Intern ational Symposium on the Ordovician System. A brief account is given concer ning the global Ordovician chronostratigraphy and the correlation of the ma in regional series and stages. (C) 2000 Elsevier Science B.V. All rights re served.