Organic-walled dinoflagellate cysts in biostratigraphy: state of the art and perspectives for future research

Over the past 70 years, the potential of organic-walled dinoflagellate cysts (or dinocysts) for the dating and correlation of marine deposits from the Upper Triassic onwards has been increasingly realized, and dinocyst biostratigraphy has developed into a valuable stratigraphic method both in academic and industrial applications. Its utility is traditionally considered to be greatest in shelfal settings, but dinocyst biostratigraphy has also been successfully applied to deep-ocean sedimentary successions. As such, dinocystderived age information is complementary to that of other microfossil groups with typically more offshore distribution centers such as planktonic foraminifera, calcareous nannofossils, diatoms, and radiolaria. Due to the limited preservation potential of calcareous and siliceous microfossils in high-latitude settings, dinocysts are particularly important for age determinations in polar to sub-polar regions. The versatility of dinocyst signals is further enhanced in microscope slide preparations containing these microfossils because they typically also include terrestrial palynomorphs such as pollen and spores, yielding direct land-sea correlations. Regardless of its impressive potential, dinocyst biostratigraphy comes with specific challenges. The present article aims to provide a critical and comprehensive review of dinocyst biostratigraphy. It first discusses the principles of dinocyst morphology and taxonomy, as well as current concepts in dinoflagellate (cyst) paleo-ecology, because accurate identification and an understanding of environmental tolerances are indispensable for successful dinocyst-based biostratigraphic analysis. It then considers the suitability of dinocysts as bi-ostratigraphic markers in terms of morphological distinctiveness and abundances, taxonomic diversity, strati-graphic ranges, and (paleo-) geographic distributions. Finally, it identifies perspectives and potential for fu-ture work.