Editing Acritarch (section)

==Occurrence==

Acritarchs are found in sedimentary rocks from the present back into the [[Archean]].<ref>{{cite journal |year=2003 |title=Montenari, M. & Leppig, U. (2003): The Acritarcha: their classification morphology, ultrastructure and palaeoecological/palaeogeographical distribution. |journal=Paläontologische Zeitschrift |volume=77 |pages=173–194 |doi=10.1007/bf03004567 |s2cid=127238427}}</ref> They are typically isolated from siliciclastic sedimentary rocks using [[hydrofluoric acid]] but are occasionally extracted from carbonate-rich rocks. They are excellent candidates for index fossils used for dating rock formations in the [[Palaeozoic|Paleozoic]] Era and when other fossils are not available. Because most acritarchs are thought to be marine (pre-Triassic), they are also useful for palaeoenvironmental interpretation.

The Archean and earliest [[Proterozoic]] microfossils termed "acritarchs" may actually be prokaryotes. The earliest eukaryotic acritarchs known ({{As of|2020|lc=y}}) are from between 1950 and 2150 million years ago.<ref>{{cite journal |last1=Yin |first1=Leiming |title=Microfossils from the Paleoproterozoic Hutuo Group, Shanxi, North China: Early evidence for eukaryotic metabolism |journal=Precambrian Research |volume=342 |pages=105650 |date=Feb 2020 |doi=10.1016/j.precamres.2020.105650|bibcode=2020PreR..34205650Y |doi-access=free }}</ref>