''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 classification
[Williams 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