Calcareous dinoflagellate cysts


Calcareous dinoflagellate cysts or calcareous dinocysts are dinoflagellate cysts produced by a group of peridinoid dinoflagellates, called calcareous dinoflagellates.

Definition

Organisms producing calcareous structures are exclusively found in a small group of peridinoid dinoflagellates, called calcareous dinoflagellates. Such calcareous structures are either dinocysts, which are formed during the life cycle or found in vegetative stages. The potential to produce calcareous structures has been considered as apomorphic within alveolates, arguing for the monophyly of Calciodinellaceae.

Distribution and ecology

Calciodinellaceae comprise 35 extant species of calcareous dinophytes, plus about 260 fossil species. They are distributed in cold through tropical seas of the world. Calcareous cysts are deposited in both marine sediments that are coastal and oceanic. The first freshwater dinoflagellate that produces calcareous cysts was recently discovered.

Fossil record

According to the fossil record, calcareous dinoflagellates originate in the Upper Triassic and are highly diverse during the Cretaceous and throughout the Tertiary.

Systematics

Due to their long stratigraphic range, many fossil species have been described. By contrast, descriptions of extant species are primarily based on the motile stages.
This has led to two distinct systematics: paleontological and neontological.