It is a fossil species of dinoflagellate cyst used to demarcate the K/Pg boundary, which marks the terminal Cretaceous and the extinction of the dinosaurs.

[1] 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.

Organic-walled dinoflagellate cysts are noted for their resistance to degradation owing to their composition of dinosporin, a biopolymer similar to sporopolinin characteristic of many terrestrial palynomorphs.

[4][5] Their abundance, cosmopolitan distribution, and quality of preservation in the fossil record since the Middle Triassic[6][7] make dinoflagellate cysts excellent indicators of primary productivity[8][9] as well as tools for biostratigraphy and paleoenvironmental reconstructions.

[10][11] The scope of dinoflagellate cyst applications has resulted in ongoing collaborative efforts between industry and academia to refine their taxonomic classification[12] and enhance their utility through database organization.