Fossil dinoflagellate diversity, originations, and extinctions and their significance

Abstract

Dinoflagellates, single-celled protists at or near the base of the food chain, showed remarkable patterns in species diversity in the Mesozoic–Cenozoic. First appearing in the mid Triassic, they rapidly increased to a Jurassic maximum of 420 species in the Kimmeridgian. After a minor decline, diversity rose to an all-time peak of 584 in the Albian, followed by a significant drop to 315 in the Coniacian: this may in part reflect the short duration of that stage. Diversity then recovered to a second Cretaceous peak of 568 in the Maastrichtian, followed by a major decline in the Early Paleocene (361 species), although relatively few of these species appear to have become extinct at the Cretaceous–Tertiary boundary. Other than a major peak of 518 in the Early Eocene, there is a continuing decrease through the Tertiary. Our plots are based on over 30 000 records of age ranges from a major database. Although previous studies show similar plots, these were based on manually compiled records of substantially fewer species. Nevertheless, the resemblance between our plots and earlier ones is striking, supporting the premise that the patterns reflect natural events and processes rather than artifacts of literature or methodology. The present species diversity plot shows some similarity to the long-term sea-level curve, which may reflect the preference of dinoflagellates for shelf environments. Keywords: dinoflagellates, diversity, plankton, extinctions, fossils, paleoecology.

Geochemical and palynological sea-level proxies in hemipelagic sediments: A critical assessment from the Upper Cretaceous of the Czech Republic

“…1; MacRae et al, 1996;Fensome et al, 1997;Sluijs et al, 2005). In terms of inshore to offshore trends, the expected pattern would be to see an increase in diversity and a decline in absolute abundance accompanying sea-level rise, representing the transition from a near-shore to a deeper water environment with lower nutrient availability.…”

Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: Evaluating the potential for a CO2 proxy

“…Consequently, dinocysts are typically found in sediments that are not completely oxidized. Dinocysts are found in sediments as old as the Triassic ($215 Ma) and have provided valuable biostratigraphic tools and paleoenvironmental proxies on geological timescales (MacRae et al, 1996;Sluijs et al, 2005). Furthermore, cysts of many dinoflagellate species, including the ones of G. spinifera and P. reticulatum, can be found in sediments of very different oceanographic settings; i.e., they have a high tolerance for a range of nutrient concentrations and temperatures and Table 1. can thus be considered as cosmopolitan (Zonneveld et al, 2013).…”

Oldest Fossil Records of Marine Protists and the Geologic History Toward the Establishment of the Modern-Type Marine Protist World

“…This may be interpreted by the fact that characteristic tabulation and/or archeopyles fi rst appeared in dinofl agellate lineages since the Middle Triassic (Le Herisse et al 2012 ) or the "switching on" of preservable cyst-forming capability (Medlin and Fensome 2013 ). After the Middle Triassic, fossil records of dinofl agellate cysts become rich and continued (MacRae et al 1996 ;Fensome et al 1999 ).…”