Microfossils from the lower Mesoproterozoic Kaltasy Formation, East European Platform

“Revista Espanola de Micropaleontologia (numero extraordinario), 1-203, pis I-XXIII.”

“Geochemical data on iron-speciation, nitrogen isotopes, and trace metal abundances and isotopes concur in suggesting the surface mixed layer of mid-Proterozoic oceans lay above widespread and persistent anoxic water masses; episodic upward mixing of these subsurface waters may have inhibited eukaryotic diversification…”

“…examined to date do not show recognizably chlorophyte ultrastructures (Javaux et al., 2004) and so, informed by molecular clocks (e.g., Parfrey et al., 2011; Eme et al., 2014), the range of potential eukaryotic sources for these fossils must include undiagnostic crown group green…”

“There is consensus that Leiosphaeridia species reflect a variety of biological origins, nonetheless, leiosphaerids have commonly been interpreted as green algae, either the phycomata of prasinophyte green algae (Tappan, 1980) or chlorophyte cell walls (Moczydłowska, 2010; Moczydłowska et al., 2010).”

“Although basinal environments in many lower Mesoproterozoic basins were anoxic, and sometimes euxinic (Sperling et al., 2015, and references therein), Fe-speciation geochemistry of the Kaltasy succession indicates oxic water throughout the range of depths recorded by the succession (Sperling et…”

“Molecular phylogenies now make it clear that, as circumscribed, this group is not monophyletic (e.g., Giovannoni et al., 1988; Schirrmeister et al., 2015), but whether simple filamentous multicellularity evolved once within the cyanobacteria and was lost several times (Schirrmeister et al., 2015)…”

“Ecological variation along environmental depth gradients is characteristic of modern oceans, and it has been documented previously in both younger and contemporaneous Proterozoic basins (Knoll, 1984; Butterfield and Chandler, 1992; Javaux et al., 2001).”

“Geochemical data on iron-speciation, nitrogen isotopes, and trace metal abundances and isotopes concur in suggesting the surface mixed layer of mid-Proterozoic oceans lay above widespread and persistent anoxic water masses; episodic upward mixing of these subsurface waters may have inhibited eukaryotic diversification…”

“, 1991) and partitioned into species on the basis of size frequency distribution (Butterfield et al., 1994); on this basis, we recognize five species (S.”

“within the cyanobacteria and was lost several times (Schirrmeister et al., 2015) or evolved multiple times convergently (Ishida et al.”

“Today, benthic multicellular algae grow beneath storm wave base, indeed, at depths greater than 200 m (Littler et al., 1985).”

“, 2004) and so, informed by molecular clocks (e.g., Parfrey et al., 2011; Eme et al., 2014), the range of potential eukaryotic sources for these fossils must include undiagnostic crown group green algae, stem group greens, stem group archaeoplastids (the photosynthetic group that includes green, red, and glaucocystoph…”

“…and Baicaoping formations of the Ruyang Group, China (Xiao et al., 1997; Pang et al., 2013; Agi et al., 2015); the Roper Group, Australia (Javaux et al., 2001, 2004); the Chitrakut, Rampur and Deonar formations of the Semri Group and the Bahraich Group, India (Prasad and Asher, 2001;…”

“Type I assemblages lack conspicuously ornamented acritarchs but contain abundant small coccoidal (e.g. Ostiana, Myxococcoides, Synsphaeridium) and filamentous (e.g., Siphonophycus, Leiotrichoides, Brevitrichoides) microfossils not exceeding a hundred microns in diameter; prokaryotic microorganisms account for much of…”

“C29 steranes, widely accepted as biomarkers for green algae, first become significant constituents of sedimentary organic matter in Ediacaran strata (Knoll et al., 2007; Bhattacharya and Dutta, 2015); thus, if greens are represented among Kaltasy and other early Mesoproterozoic microfossil…”

“[Many prasinophytes synthesize mainly C28 sterols, but C28 steranes are also rare or absent in Mesoproterozoic rocks (Kodner et al., 2008).”

“Knoll and Golubic, 1979, emend.”

“These taxa have a wide geographic distribution, being reported from the Beidajiang and Baicaoping formations of the Ruyang Group, China (Xiao et al., 1997; Pang et al., 2013; Agi et al., 2015); the Roper Group, Australia (Javaux et al., 2001, 2004); the Chitrakut, Rampur and Deonar formations of the Semri Group and th…”

“Taphonomic observation and experiments show that cyanobacterial sheaths preserve better than the trichomes they contain (Sergeev and Krylov, 1986; Bartley, 1996), and so tubular sheaths are more common in the Proterozoic fossil record than are trichomes, including in the Kaltasy assemblage.”

“Such large spheroids are commonly lumped together in Chuaria circularis, but the Kaltasy fossils differ in key characters from the Grand Canyon populations, including the lectotype designated by Ford and Breed (1973; see discussion in Vidal and Ford, 1985).”

“…remains occur in basinal, oxic environments indicates that aspects of early eukaryotic evolution may have occurred in environments not commonly sampled by paleontologists (a similar argument has been made concerning early evolution in non-marine environments; Wellman and Strother, 2015).”

“Moyeria sp. Leiosphaerid with multiple folds: Sperling et al., 2014, Figs.”

“…fossils called Archaeoellipsoides, generally found in silicified carbonates and interpreted as the akinetes of nostocalean cyanobacteria (Horodyski and Donaldson, 1980; Golubic et al., 1995; Sergeev et al., 1995), as well as their at least partial counterpart in shales Brevitrichoides…”

“28A-28G, and 28J; Butterfield, 2009, Figs.”

“In all likelihood, at least one of the preserved walls was vegetative, and living eukaryotes with continuous vegetative walls are nearly all photosynthetic or osmotrophic (Margulis et al., 1990; Teyssèdre, 2006; Moczydłowska et al., 2011).”

“Ornamented acritarchs found in upper Paleoproterozoic and lower Mesoproterozoic formations elsewhere (e.g., Yin, 1997; Prasad et al., 2005; Nagovitsin, 2009; Adam, 2014; Singh and Sharma, 2014; Agi et al., 2015) have not been identified in the Kaltasy assemblage.”

“The comparison, however, is broad, and molecular clocks suggest a much later origin of conjugating streptophyte greens (Becker, 2013).”

“They are larger than ellipsoidal akinetes of nostocalean cyanobacteria Archaeoellipsoides (= Brevitrichoides), which can be abundant in Mesoproterozoic peritidal facies (Sergeev et al., 1995); most likely, the Kaltasy specimens are the remains of eukaryotic microorganisms.”

“These fossils are much larger than ellipsoidal fossils called Archaeoellipsoides, generally found in silicified carbonates and interpreted as the akinetes of nostocalean cyanobacteria (Horodyski and Donaldson, 1980; Golubic et al., 1995; Sergeev et al., 1995), as well as their at least partial counterpart in shales Br…”

“] Tapering toward apices may be original, but can also reflect postmortem shrinkage of filaments (Golubic and Barghoorn, 1977; Gerasimenko and Krylov, 1983; Sergeev, 1992; Knoll and Golubic, 1992).”

“Protista of Upper Mesoproterozoic Ruyang Group in Shanxi Province, China.”

“It may be that some specimens interpreted as sheaths are in fact compressed ensheathed trichomes in which cross walls have been lost (Golubic and Barghoorn, 1977; Gerasimenko and Krylov, 1983; Hofmann and Jackson, 1994; Sergeev et al., 1995); however, the Kaltasy population exhibits features best interpreted in terms…”

“This simple and effective technique avoids the requirement for centrifugation and heavy liquid treatment, facilitating the intact preservation of large microfossils (e.g., Grey, 1999, 2005; Willman and Moczydłowska, 2008; Sergeev et al., 2011).”

“The age of Kaltasy correlatives in the southern Ural Mountains is constrained by the ~1380 Ma Mashak volcanics in the overlying Middle Riphean (Mesoproterozoic) Yurmata Group (Puchkov et al., 2013; Krasnobaev et al., 2013a) and by ~1750 Ma basalts 200 meters above the base of the Ai Formation (Puchkov et al., 2012, Kr…”

“and Neoproterozoic specimens, supporting their interpretation as chlorophytes (Talyzina and Moczydłowska, 2000; and, with less certainty, Moczydłowska et al., 2010).”

“…have a wide geographic distribution, being reported from the Beidajiang and Baicaoping formations of the Ruyang Group, China (Xiao et al., 1997; Pang et al., 2013; Agi et al., 2015); the Roper Group, Australia (Javaux et al., 2001, 2004); the Chitrakut, Rampur and Deonar formations of the…”

“Miller and Eames, 1982 (?)”

“1 and 2; Sergeev and Schopf, 2010, p. 395, 396, Figs.”

“…associations of evolutionarily conserved cyanobacteria may prove biostratigraphically informative in some Mesoproterozoic successions, because they are closely tied to physical environments that themselves are limited in time (Knoll and Sergeev, 1995; Sergeev et al., 1995; Sergeev, 2006, 2009).”

“…microfossils with robust opaque walls that are the remains of either unicellular eukaryotic cells or empty envelopes of prokaryotic colonies (See Vidal and Ford, 1985; Fairchild, 1985; Yankauskas, 1989; Butterfield et al., 1994; Sergeev, 2006; Sergeev et al., 2012 for additional discussion).”

“This simple and effective technique avoids the requirement for centrifugation and heavy liquid treatment, facilitating the intact preservation of large microfossils (e.g., Grey, 1999, 2005; Willman and Moczydłowska, 2008; Sergeev et al., 2011).”

“…of the Semri Group and the Bahraich Group, India (Prasad and Asher, 2001; Prasad et al., 2005; Singh and Sharma, 2014); the Newland Formation of the Belt Supergroup, USA (Adam, 2014), and the Dalgokta and Dzhelindukon formations of the Kamo Group, Central Angara Basin, Siberia (Nagovitsin, 2009).”

“…Ural Mountains is constrained by the ~1380 Ma Mashak volcanics in the overlying Middle Riphean (Mesoproterozoic) Yurmata Group (Puchkov et al., 2013; Krasnobaev et al., 2013a) and by ~1750 Ma basalts 200 meters above the base of the Ai Formation (Puchkov et al., 2012, Krasnobaev et al., 2013b).”

“…biotas, but additionally include large structures such as Eosolena, Elatera, and Rectia magna, as observed in the Kotuikan and Ust’-Il’ya formations of the Anabar Uplift, Siberia (Veis et al., 2001; Vorob’eva et al., 2015), and the McMinn Formation of the Roper Group, Australia (Peat et al., 1978).”

“We cannot exclude the possibility that some specimens assigned to Navifusa sp. (e.g., Fig.”

“Buick and Knoll, 1999 Figure 8.7 Siphonophycus punctatus Maithy, 1975, p. 137, pl. 1, Fig.”

“Large filamentous forms comprise large, relatively complex microfossils plausibly interpreted as the remains of eukaryotic algae because they exceed the maximal width of known cyanobacterial filaments (~100 μm; Schopf, 1992).”

“Buick and Knoll, 1999 Figure 8.7 Siphonophycus punctatus Maithy, 1975, p. 137, pl. 1, Fig.”

“Type I assemblages lack conspicuously ornamented acritarchs but contain abundant small coccoidal (e.g. Ostiana, Myxococcoides, Synsphaeridium) and filamentous (e.g., Siphonophycus, Leiotrichoides, Brevitrichoides) microfossils not exceeding a hundred microns in diameter; prokaryotic microorganisms account for much of…”

“There is consensus that Leiosphaeridia species reflect a variety of biological origins, nonetheless, leiosphaerids have commonly been interpreted as green algae, either the phycomata of prasinophyte green algae (Tappan, 1980) or chlorophyte cell walls (Moczydłowska, 2010; Moczydłowska et al., 2010).”

“The genus Moyeria was erected for distinctive Ordovician and Silurian microfossils recovered from fluviatile successions and interpreted as the preserved pellicle of a euglenid protist (Gray and Boucot, 1989).”

“…associations of evolutionarily conserved cyanobacteria may prove biostratigraphically informative in some Mesoproterozoic successions, because they are closely tied to physical environments that themselves are limited in time (Knoll and Sergeev, 1995; Sergeev et al., 1995; Sergeev, 2006, 2009).”

“Since that time, however, both the longer stratigraphic range of many simple Neoproterozoic microfossils and the importance of facies in Proterozoic micropaleontology have become more fully appreciated (e.g., Sergeev, 1992, 2009; Sergeev et al., 1995, 2010; Kah et al., 2007).”

“Remarks: This form is similar to Moyeria species described from the Paleozoic deposits (Molyneux et al., 2008; Le Hèrissè et al., 2013) and interpreted as euglenid pellicles.”

“Silicified coastal carbonate facies offer a view of benthic microbes, including abundant and diverse cyanobacteria (e.g., Zhang, 1981; Sergeev et al., 1995, 2007; Kumar and Srivastava, 1995), while carbonaceous compressions in fine-grained siliciclastic lithologies”

“Recently Pang et al., 2015 suggested a secondary origin for Plicatidium folds.”

“…Ural Mountains is constrained by the ~1380 Ma Mashak volcanics in the overlying Middle Riphean (Mesoproterozoic) Yurmata Group (Puchkov et al., 2013; Krasnobaev et al., 2013a) and by ~1750 Ma basalts 200 meters above the base of the Ai Formation (Puchkov et al., 2012, Krasnobaev et al., 2013b).”

“…rocks, divided into the Burzyan, Yurmata, Karatau and Arsha groups, separated by unconformities (the Arsha Group, which occurs only on the eastern limb of the Bashkirian meganticlinorium, was recently added to the Riphean as a result of new isotopic data; Puchkov, 2005, 2013).”

“There is consensus that Leiosphaeridia species reflect a variety of biological origins, nonetheless, leiosphaerids have commonly been interpreted as green algae, either the phycomata of prasinophyte green algae (Tappan, 1980) or chlorophyte cell walls (Moczydłowska, 2010; Moczydłowska et al., 2010).”

“…accepted as biomarkers for green algae, first become significant constituents of sedimentary organic matter in Ediacaran strata (Knoll et al., 2007; Bhattacharya and Dutta, 2015); thus, if greens are represented among Kaltasy and other early Mesoproterozoic microfossil assemblages, they would…”

“Downie and Sarjeant, 1963 Type species: Leiosphaeridia baltica Eisenack, 1958 Leiosphaeridia (?)wimanii Brotzen, 1941, emend. and comb.”

“In all likelihood, at least one of the preserved walls was vegetative, and living eukaryotes with continuous vegetative walls are nearly all photosynthetic or osmotrophic (Margulis et al., 1990; Teyssèdre, 2006; Moczydłowska et al., 2011).”

“This, however, does not mean that all spheroidal acritarchs were sourced by green algae, as potentially preservable spheroidal envelopes are made by organisms ranging from cyanobacteria (e.g., Fairchild, 1985; Sun, 1987; Sergeev, 1992) to ciliates (e.g., Villalobo et al., 2003).”

“Remarks: This form is similar to Moyeria species described from the Paleozoic deposits (Molyneux et al., 2008; Le Hèrissè et al., 2013) and interpreted as euglenid pellicles.”

“Kaltasy strata include mixed carbonates and shales, correlated with the Satka Formation in the Ural Mountains (Keller and Chumakov, 1983; Kah et al., 2007; Kozlov et al., 2009); the 1230 to 3600 m succession has been subdivided into three conformable members: Sauzovo, Arlan and Ashit.”

“Silicified coastal carbonate facies offer a view of benthic microbes, including abundant and diverse cyanobacteria (e.g., Zhang, 1981; Sergeev et al., 1995, 2007; Kumar and Srivastava, 1995), while carbonaceous compressions in fine-grained siliciclastic lithologies record both benthic and…”

“…(Hermann and Timofeev, 1985) consists of uniseriate filaments, several millimeters long, with constituent cells up to 150 μm wide and variably constricted at prominent septum-like transverse walls (Yankauskas, 1989; Hermann, 1990; Hermann and Podkovyrov, 2009, 2014; Vorob’eva et al., 2015).”

“Recent work, using less aggressive separation techniques, hints at higher diversity within individual mid-Proterozoic formations (e.g., Sergeev et al., 2016; Beghin et al., 2017); however, these new findings do not greatly expand the known diversity of pre-Tonian eukaryotes.”

“The Mainoru Formation, Roper Group, Australia; the Lakhanda Group, Neryuen Formation, Uchur-Maya region, Siberia (Jankauskas, 1989); the Koltasy Formation, Russia (Sergeev et al., 2016); the El Mreiti Group, Taoudeni Basin, Mauritania (Beghin et al., in review).”

“An analysis of drill core from the 1400 Ma Kaltasy Formation (Russia) revealed a suite of oxic samples, but definitive eukaryotes are rare or absent [68,69].”

“…organic-walled microfossil assemblages seem to be broadly similar worldwide, despite some differences possibly related to redox conditions (e.g. Sergeev et al., 2016), facies preservation, sample preparation, lack of recent detailed taxonomic revision, or sampling bias; but similarities may…”

“Some larger Pro-terozoic specimens (300–550 µm long and 190–375 µm wide) were interpreted as probable eukaryotes 54 .”

“…by comparison with the Mesoproterozoic record (Yan & Liu, 1993; Javaux, Knoll & Walter, 2004; Lamb et al. 2009; Agić, Moczydłowska & Yin, 2015; Sergeev et al. 2016), contributed to steady oxygenation of surface waters by the release of free oxygen, increased the production of net organic…”

“7.5 of Sergeev et al. 2016), likely reflecting taphomorphic and/or ontogenetic variation.”

“Ever since, diverse NPP with eukaryotic characters have been recovered from numerous sedimentary successions from the terminal Paleoproterozoic and early Mesoproterozoic: c. 1.6–1.4 Ga Ruyang Group in the North China Craton (Agic ́ et al. 2017), c. 1.6–1.4 Ga Vindhyan Supergroup in India (Prasad et al. 2005), c. 1.5–1…”

“These shales have high total organic carbon (TOC) and favorable source rock potential (Su et al. 2010; Zhang et al. 2015; Wang et al. 2017b; Mitch-ell et al. 2021; Lyu et al. 2021; Xie et al. 2022; He et al. 2022; Sergeev et al. 2016; Canfield et al. 2020).”

“Recently, it was found that the replacement of oxygenic (oxidating) conditions by anaerobic (reducing) conditions in the zones of microbiota dwelling influenced the taxonomic composition of benthic Lower Riphean microbiota as well (Sergeev et al., 2015; Sperling et al., 2015; Sergeev et al., 2016) (for more detail, pl…”

“2008; Sergeev et al .”

“The data of last 10–15 years, however, supported the high level of evolution of the Precambrian microflora as early as the Early Riphean (Sergeev, 2006, 2009; Sergeev et al., 2010, 2016, 2017).”