Evidence for eukaryotic diversification in the ∼1800 million-year-old Changzhougou Formation, North China

Lamb, David; Awramik, Stanley M.; Chapman, D. J.; Zhu, Shifa

doi:10.1016/j.precamres.2009.05.005

Cited by 108 publications

(61 citation statements)

References 48 publications

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“…The 1.88-Ga Gunflint Formation occupies a key point in Earth's history. It shortly predates the earliest widely accepted evidence for fossil eukaryotes (9) and the generally accepted timing of the transition from largely ferruginous to largely sulfidic ocean conditions (10,11). Recent work suggests that this transition was prolonged and spatially variable, with oxygenated surface waters potentially underlain by sulfidic wedges and deeper ferruginous waters for much of the mid-to late Proterozoic (12,13).…”

mentioning

confidence: 89%

Nanoscale analysis of pyritized microfossils reveals differential heterotrophic consumption in the ∼1.9-Ga Gunflint chert

Wacey

McLoughlin

Kilburn

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The 1.88-Ga Gunflint biota is one of the most famous Precambrian microfossil lagerstätten and provides a key record of the biosphere at a time of changing oceanic redox structure and chemistry. Here, we report on pyritized replicas of the iconic autotrophic GunflintiaHuroniospora microfossil assemblage from the Schreiber Locality, Canada, that help capture a view through multiple trophic levels in a Paleoproterozoic ecosystem. Nanoscale analysis of pyritic Gunflintia (sheaths) and Huroniospora (cysts) reveals differing relic carbon and nitrogen distributions caused by contrasting spectra of decay and pyritization between taxa, reflecting in part their primary organic compositions. In situ sulfur isotope measurements from individual microfossils (δ 34 S V-CDT +6.7‰ to +21.5‰) show that pyritization was mediated by sulfate-reducing microbes within sediment pore waters whose sulfate ion concentrations rapidly became depleted, owing to occlusion of pore space by coeval silicification. Three-dimensional nanotomography reveals additional pyritized biomaterial, including hollow, cellular epibionts and extracellular polymeric substances, showing a preference for attachment to Gunflintia over Huroniospora and interpreted as components of a saprophytic heterotrophic, decomposing community. This work also extends the record of remarkable biological preservation in pyrite back to the Paleoproterozoic and provides criteria to assess the authenticity of even older pyritized microstructures that may represent some of the earliest evidence for life on our planet. biogeochemistry | taphonomy | paleontology

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mentioning

confidence: 89%

Nanoscale analysis of pyritized microfossils reveals differential heterotrophic consumption in the ∼1.9-Ga Gunflint chert

Wacey

McLoughlin

Kilburn

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…In the 750 Ma Chuar Group from the Grand Canyon, vase-shaped microfossils preserved as casts coated with pyrite provide less wall definition that those preserved as siliceous or organic-coated casts (Porter & Knoll 2000). By contrast, in mid-Proterozoic sediments where preservation is particularly good, pyrite is conspicuously lacking -for example, in the Changchang Group, north China (Lamb et al 2009). These relationships are consistent with those observed in the Torridonian Supergroup and the combined evidence suggests that the heterotrophic consumption of cellular organic material by sulphate-reducing bacteria may have restricted the quality of the Proterozoic fossil record.…”

Section: Implications For the Fossil Recordmentioning

confidence: 99%

“…However, although acid-resistant vesicles (acritarchs) of inferred eukaryote origin are known from 1.8 Ga and became moderately diverse in nearshore habitats by 1.45 Ga (Lamb et al 2009), overall the midProterozoic record is very limited. Some researchers attribute this to evolutionary stasis in the marine realm during the 'boring billion', when high levels of hydrogen sulphide, which is toxic to eukaryotes, inhibited their evolutionary radiation , and latterly to the concept that major evolutionary innovations may have mostly been taking place on land at this time (Blank 2013;Wellman & Strother 2015).…”

mentioning

confidence: 99%

Contrasting microfossil preservation and lake chemistries within the 1200–1000 Ma Torridonian Supergroup of NW Scotland

Wacey

Brasier

Parnell

et al. 2016

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Oxygenation of the Proterozoic atmosphere caused the progressive build-up of dissolved sulphate on the continents and in marine environments. However, oxygen levels in the Proterozoic were low enough to allow the early burial of biological material into low redox potential environments where permineralization and the authigenic replacement of organic material, including micro-organisms, occurred by a range of minerals. Consequently, microbial sulphate reduction caused the widespread degradation of organic matter and, where iron was available, the precipitation of pyrite. By contrast, where sulphate levels were low, early preservation by other minerals (e.g. phosphate or silica) could be excellent. We show, using two Proterozoic lake sequences with low and high sulphate chemistries, but with otherwise similar characteristics, that microbial sulphate reduction caused a profound loss of morphological detail and diversity within preserved microfossils. The results could imply that there is a significant bias in the Proterozoic fossil record towards low sulphate environments, which were in reality relatively scarce.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

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“…Single primary symbiosis and the origin of plastids that gave rise to Plantae (alternatively called Viridiplantae or Archaeplastida, Cavalier-Smith, 2003;Keeling, 2002, 2004;Baldauf, 2008) are broadly estimated by molecular clocks to have evolved by 1.5 Ga (Yoon et al, 2004;Hackett et al, 2007). The timing of this event in the paleontological record could be prior to 1.8 Ga, if the green algal affinity of leiosphaerid microfossils described by Lamb et al (2009) is accepted (Moczydłowska et al, 2011). However, the "cryptic" intracellular evolution through which a cell acquired a characteristic eukaryotic architecture might have occurred before c. 2.1 Ga (Runnegar, 1994).…”

Section: Introductionmentioning

confidence: 99%

Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China

Agić¹,

Moczydłowska²,

Yin

2015

J. Paleontol.

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Abstract.-Light microscope and scanning electron microscope observations on new material of unicellular microfossils Dictyosphaera macroreticulata and Shuiyousphaeridium macroreticulatum, from the Mesoproterozoic Ruyang Group in China, provide insights into the microorganisms' biological affinity, life cycle and cellular complexity. Gigantosphaeridium fibratum n. gen. et sp., is described and is one of the largest Mesoproterozoic microfossils recorded. Phenotypic characters of vesicle ornamentation and excystment structures, properties of resistance and cell wall structure in Dictyosphaera and Shuiyousphaeridium are all diagnostic of microalgal cysts. The wide size ranges of the various morphotypes indicate growth phases compatible with the development of reproductive cysts. Conspecific biologically, each morphotype represents an asexual (resting cyst) or sexual (zygotic cyst) stage in the life cycle, respectively. We reconstruct this hypothetical life cycle and infer that the organism demonstrates a reproductive strategy of alternation of heteromorphic generations. Similarly in Gigantosphaeridium, a metabolically expensive vesicle with processes suggests its protective role as a zygotic cyst. In combination with all these characters and from the resemblance to extant green algae, we propose the placement of these ancient microorganisms in the stem group of Chloroplastida (Viridiplantae). A cell wall composed of primary and secondary layers in Dictyosphaera and Shuiyouisphaeridium required a high cellular complexity for their synthesis and the presence of an endomembrane system and the Golgi apparatus. The plastid was also present, accepting the organism was photosynthetic. The biota reveals a high degree of morphological and cell structural complexity, and provides an insight into ongoing eukaryotic evolution and the development of complex life cycles with sexual reproduction by 1200 Ma.

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Evidence for eukaryotic diversification in the ∼1800 million-year-old Changzhougou Formation, North China

Cited by 108 publications

References 48 publications

Nanoscale analysis of pyritized microfossils reveals differential heterotrophic consumption in the ∼1.9-Ga Gunflint chert

Nanoscale analysis of pyritized microfossils reveals differential heterotrophic consumption in the ∼1.9-Ga Gunflint chert

Contrasting microfossil preservation and lake chemistries within the 1200–1000 Ma Torridonian Supergroup of NW Scotland

Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China

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