NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Paleobiology of the Mesoproterozoic Billyakh Group, Anabar Uplift, northern SiberiaSilicified peritidal carbonates of the Mesoproterozoic Kotuikan and Yusmastakh Formations, Anabar Uplift, northeastern Siberia, contain exceptionally well-preserved microfossils. The assemblage is dominated by ellipsoidal akinetes of nostocalean cyanobacteria (Archaeoellipsoides) and problematic spheroidal unicells (Myxococcoides); both are allochthonous and presumably planktonic. The assemblage also includes distinctive mat-forming scytonematacean and entophysalidacean cyanobacteria, diverse short trichomes interpreted as cyanobacterial hormogonia or germinated akinetes, rare longer trichomes, and several types of colonial unicells. Although many taxa in the Kotuikan-Yusmastakh assemblage are long-ranging prokaryotes, the overall character of the assemblage is distinctly Mesoproterozoic, with its major features shared by broadly coeval floras from Canada, China, India, and elsewhere in Siberia. Microfossils also occur in middle to inner shelf shales of the Ust'-Il'ya and lower Kotuikan Formations. Leiosphaerid acritarchs (up to several hundred microns in diameter) characterize this facies. As in other Mesoproterozoic acritarch assemblages, acanthomorphic and other complex forms that typify Neoproterozoic assemblages are absent. The combination in Billyakh assemblages of exceptional preservation and low eukaryotic diversity supports the hypothesis that nucleated organisms diversified markedly near the Mesoproterozoic-Neoproterozoic boundary. The assemblages also demonstrate the antiquity of cyanobacteria capable of cell differentiation and suggest the importance of both changing peritidal substrates and evolving eukaryotes in determining stratigraphic patterns of Proterozoic prokaryotes. The permineralized assemblage contains 33 species belonging to 17 genera. Ten new species or new combinations are proposed: Archaeoellipsoides costatus n. sp., A. elongatus n. comb., A. dolichos n. comb., A. minor n. nom., A. crassus n. comb., A. major n. comb., A. bactroformis n. sp., Veteronostocale medium n. sp., Filiconstrictosus cephalon n. sp., and Partitiofilum yakschinii n. sp.
Document ID
20040089690
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Sergeev, V. N.
(Geological Institute, Russian Academy of Sciences Moscow)
Knoll, A. H.
Grotzinger, J. P.
Date Acquired
August 21, 2013
Publication Date
January 1, 1995
Publication Information
Publication: Journal of paleontology
Volume: 69
Issue: 1 Pt 2
ISSN: 0022-3360
Subject Category
Geosciences (General)
Funding Number(s)
CONTRACT_GRANT: EAR 9058199
CONTRACT_GRANT: 9305-9403
CONTRACT_GRANT: NAGW-893
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology

Available Downloads

There are no available downloads for this record.
No Preview Available