''Palynodinium'' is an extinct genus of organic-walled dinoflagellate cyst (or dinocyst). It is a fossil species of dinoflagellate cyst used to demarcate the K/Pg boundary, which marks the terminal

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

and the extinction of the dinosaurs. ''Palynodinium grallator'' was among the microfossils which lead to the recent discovery of the K/Pg event record in marine sediments of the northeast Pacific. Dinoflagellate cysts are estimated to be produced by 10–16% of living

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s as a dormant,

zygotic A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicellula ...

stage of their life cycle, which can accumulate in marine sediments as microfossils. Organic-walled dinoflagellate cysts are noted for their resistance to degradation owing to their composition of

dinosporin Dinosporin is a macromolecular, highly resistant organic compound which forms or partly forms, the enclosing wall of fossilizable organic-walled dinoflagellate cysts. Composition The walls of organic-walled dinocysts are composed of the resistant ...

, a biopolymer similar to sporopolinin characteristic of many terrestrial

palynomorphs Palynology is the "study of dust" (from grc-gre, παλύνω, palynō, "strew, sprinkle" and ''-logy'') or of "particles that are strewn". A classic palynologist analyses particulate samples collected from the air, from water, or from deposits ...

. Their abundance, cosmopolitan distribution, and quality of preservation in the fossil record since the Middle

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

make dinoflagellate cysts excellent indicators of

primary productivity In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...

as well as tools for

biostratigraphy Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictiona ...

and paleoenvironmental reconstructions. The scope of dinoflagellate cyst applications has resulted in ongoing collaborative efforts between industry and academia to refine their taxonomic classificationWilliams GL, Fensome R, MacRae RA. 2017. DINOFLAJ3. American Association of Stratigraphic Palynologists, Data Series No 2.http://dinoflaj.smu.ca/dinoflaj3/index.php/Palynodinium_grallator and enhance their utility through database organization.

References

{{Taxonbar, from=Q111910255 Endosymbiotic events Cretaceous geology Events that forced the climate Extinction events Paleogene geology Palynology