''Palynodinium'' is an extinct genus of organic-walled dinoflagellate cyst (or dinocyst). It is a

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

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 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

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 (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

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. The sexual ...

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 resistan ...

, a

biopolymer Biopolymers are natural polymers produced by the cells of living organisms. Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers, ...

similar to sporopolinin characteristic of many terrestrial

palynomorphs Palynology is the study of microorganisms and microscopic fragments of mega-organisms that are composed of acid-resistant organic material and occur in sediments, sedimentary rocks, and even some metasedimentary rocks. Palynomorphs are the mic ...

. Their abundance,

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

, and quality of preservation in the fossil record since the Middle

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

make dinoflagellate cysts excellent indicators of

primary productivity Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...

as well as tools for

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

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 Dinoflagellates Dinoflagellate biology Endosymbiotic events Cretaceous–Paleogene boundary Cretaceous geology Events that forced the climate Extinction events Paleogene geology Palynology