Paleontological Evidence for Dinoflagellates and Ciliates as Early Eukaryotes
نویسندگان
چکیده
Molecular trees and geochemical markers suggest the divergence of dinoflagellates as early eukaryotes (~650 million years ago), but traditional fossil record cysts (dinocysts) starts during Triassic (~230 ago). A re-evaluation pre-Triassic shows that many acritarchs (microfossils uncertain affinities) are dinocysts representing “missing” evidence. Traditional diagnostic criteria for dinocysts, based on morphologic comparisons with motile stages, biased towards thecate species. The approach proposed here, more natural comparison living cysts, includes athecate Many species would be “acritarchs” if found fossils, earlier accepted dinoflagellate living. earliest represent an innovation profound implications evolution: a cell wall sporopollenin-like material enabling survival from microbial attack, in then microbial-dominated world. Related most likely evolved protection crucial stages sexual reproduction (e.g., ciliates dinoflagellates, spores pollen algae plants). Ciliates may have response to extreme climatic conditions Cryogenian, where robust resting cyst advantageous. Thecate forms, possibly predatory pressure.
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ژورنال
عنوان ژورنال: Journal of Marine Science and Engineering
سال: 2023
ISSN: ['2077-1312']
DOI: https://doi.org/10.3390/jmse11030533