Early Eukaryotes in the Lakhanda Biota (Mesoproterozoic, Southeastern Siberia)-Morphological and Geochemical Evidence.

Autor: Shuvalova JV; Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, Russia. pinmuse@gmail.com.; Swinburne University of Technology, Hawthorn, Australia. pinmuse@gmail.com., Nagovitsin KE; Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.; Novosibirsk State University, Novosibirsk, Russia., Duda JP; Sedimentology and Organic Geochemistry, University of Tübingen, Tübingen, Germany., Parkhaev PY; Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, Russia.
Jazyk: angličtina
Zdroj: Doklady biological sciences : proceedings of the Academy of Sciences of the USSR, Biological sciences sections [Dokl Biol Sci] 2021 Sep; Vol. 500 (1), pp. 127-132. Date of Electronic Publication: 2021 Nov 03.
DOI: 10.1134/S0012496621050100
Abstrakt: The Mesoproterozoic Lakhanda Group (~1030 Ma) preserves one of the most diverse communities of pre-Ediacaran eukaryotes. More precisely, the Lakhanda Biota includes more than twenty taxa that have been assigned to eukaryotes with different degrees of confidence. Eight of these taxa meet current criteria for the identification of eukaryotic fossils in ancient records. These include previously described fossils such as ornamented acritarchs (Valeria lophostriata, Trachyhystrichosphaera aimika), filamentous coenocytic organisms (Aimonema ramosa, Palaeovaucheria clavata), as well as fossils with smooth-walled envelopes and single outgrowth structures (Caudosphaera expansa, Germinosphaera bispinosa, and Jacutianema solubila). In addition to these, we found as yet undescribed fossils which share remarkable similarities with Ourasphaira giraldae, a possible higher fungi species known from the (?) Meso- to Neoproterozoic of Arctic Canada. Regardless of the exact systematic affinity, these fossils can confidently be assigned to eukaryotes because of the size and high morphological complexity. Intriguingly, the organic record of the Lakhanda Formation lacks biomarkers indicative of eukaryotes (that is, regular steranes). This finding would be in line with the idea that eukaryotes were present but not significant in Mesoproterozoic marine ecosystems. However, preliminary data from an ongoing study indicate an advanced thermal maturity of the organic matter, emphasizing that this conclusion might not be drawn with absolute confidence.
(© 2021. Pleiades Publishing, Ltd.)
Databáze: MEDLINE
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