Actualistic Taphonomy of Cyanobacteria: Implications for the Precambrian Fossil Record

Bartley, Julie K.

doi:10.2307/3515192

Cited by 159 publications

(125 citation statements)

References 27 publications

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“…Overall, the decay sequence of Thiomargarita has much in common with those of other bacteria [24]. As in other bacteria, the Thiomargarita sheath is the most resistant structure to decay.…”

Section: Discussion (A) Comparison With Fossil Datamentioning

confidence: 84%

“…Although patterns of decay in animal embryos are now being studied [17,[19][20][21][22], nothing is known about decay processes or preservation potential in giant sulphur-oxidizing bacteria. Previous studies on decay of bacteria (see earlier studies [23,24] for reviews) are of limited relevance because of the comparatively small size, lack of central vacuole and lack of successive reductive division in the species studied. In order to address this issue, we experimentally infer a decay sequence for Thiomargarita, and compare the results with the patterns observed in the Doushantuo fossils and other putative fossil eukaryotes.…”

Section: Introductionmentioning

confidence: 99%

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Experimental taphonomy of giant sulphur bacteria: implications for the interpretation of the embryo-like Ediacaran Doushantuo fossils

et al. 2011

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The Ediacaran Doushantuo biota has yielded fossils interpreted as eukaryotic organisms, either animal embryos or eukaryotes basal or distantly related to Metazoa. However, the fossils have been interpreted alternatively as giant sulphur bacteria similar to the extant Thiomargarita. To test this hypothesis, living and decayed Thiomargarita were compared with Doushantuo fossils and experimental taphonomic pathways were compared with modern embryos. In the fossils, as in eukaryotic cells, subcellular structures are distributed throughout cell volume; in Thiomargarita, a central vacuole encompasses approximately 98 per cent cell volume. Key features of the fossils, including putative lipid vesicles and nuclei, complex envelope ornament, and ornate outer vesicles are incompatible with living and decay morphologies observed in Thiomargarita. Microbial taphonomy of Thiomargarita also differed from that of embryos. Embryo tissues can be consumed and replaced by bacteria, forming a replica composed of a threedimensional biofilm, a stable fabric for potential fossilization. Vacuolated Thiomargarita cells collapse easily and do not provide an internal substrate for bacteria. The findings do not support the hypothesis that giant sulphur bacteria are an appropriate interpretative model for the embryo-like Doushantuo fossils. However, sulphur bacteria may have mediated fossil mineralization and may provide a potential bacterial analogue for other macroscopic Precambrian remains.

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“…Overall, the decay sequence of Thiomargarita has much in common with those of other bacteria [24]. As in other bacteria, the Thiomargarita sheath is the most resistant structure to decay.…”

Section: Discussion (A) Comparison With Fossil Datamentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Experimental taphonomy of giant sulphur bacteria: implications for the interpretation of the embryo-like Ediacaran Doushantuo fossils

et al. 2011

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“…Moreover, taphonomic features displayed by Bangiomorpha are similar to those of other early eukaryotes, but different from those of filamentous cyanobacteria known from the Proterozoic fossil record. Bangiomorpha displays three-dimensionally competent preservation of outer and inner walls, with no cytoplasmic preservation, whereas cyanobacterial filaments with sheaths generally show competent three-dimensional preservation of the sheath, but partial or complete collapse of the cells inside (Bartley 1996). Published radiometric dates constrain Bangiomorpha only to the interval 1267G2 to 723G 3 Myr, but an unpublished Pb-Pb date of 1198G 24 Myr and physical stratigraphic relationships strongly suggest that the fossils' age lies close to the lower radiometric boundary (Butterfield 2000).…”

Section: Disparity and Diversity Among Later Proterozoic Eukaryotes (mentioning

confidence: 99%

Eukaryotic organisms in Proterozoic oceans

Knoll

Javaux

Hewitt

et al. 2006

Phil. Trans. R. Soc. B

578

409

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The geological record of protists begins well before the Ediacaran and Cambrian diversification of animals, but the antiquity of that history, its reliability as a chronicle of evolution and the causal inferences that can be drawn from it remain subjects of debate. Well-preserved protists are known from a relatively small number of Proterozoic formations, but taphonomic considerations suggest that they capture at least broad aspects of early eukaryotic evolution. A modest diversity of problematic, possibly stem group protists occurs in ca 1800-1300 Myr old rocks. 1300-720 Myr fossils document the divergence of major eukaryotic clades, but only with the Ediacaran-Cambrian radiation of animals did diversity increase within most clades with fossilizable members. While taxonomic placement of many Proterozoic eukaryotes may be arguable, the presence of characters used for that placement is not. Focus on character evolution permits inferences about the innovations in cell biology and development that underpin the taxonomic and morphological diversification of eukaryotic organisms.

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“…The process of fossilisation through calcification has been induced experimentally to study the deterioration of cellular and extracellular (EPS) products under controlled laboratory conditions [31]. Natural fossilisation and early diagenesis have been studied in freshwater carbonate deposits in carbonate regions for example in the USA and Europe [20,32,33] and non-carbonate environments of lacustrine lakes in Antarctica [34].…”

Section: Introductionmentioning

confidence: 99%

Cyanobacterial Contribution to Travertine Deposition in the Hoyoux River System, Belgium

et al. 2017

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Travertine deposition is a landscape-forming process, usually building a series of calcareous barriers differentiating the river flow into a series of cascades and ponds. The process of carbonate precipitation is a complex relationship between biogenic and abiotic causative agents, involving adapted microbial assemblages but also requiring high levels of carbonate saturation, spontaneous degassing of carbon dioxide and slightly alkaline pH. We have analysed calcareous crusts and water chemistry from four sampling sites along the Hoyoux River and its Triffoy tributary (Belgium) in winter, spring, summer and autumn 2014. Different surface textures of travertine deposits correlated with particular microenvironments and were influenced by the local water flow. In all microenvironments, we have identified the cyanobacterium Phormidium incrustatum (Nägeli) Gomont as the organism primarily responsible for carbonate precipitation and travertine fabric by combining morphological analysis with molecular sequencing (16S rRNA gene and ITS, the Internal Transcribed Spacer fragments), targeting both field populations and cultures to exclude opportunistic microorganisms responding favourably to culture conditions. Several closely related cyanobacterial strains were cultured; however, only one proved identical with the sequences obtained from the field population by direct PCR. This strain was the dominant primary producer in the calcareous deposits under study and in similar streams in Europe. The dominance of one organism that had a demonstrated association with carbonate precipitation presented a valuable opportunity to study its function in construction, preservation and fossilisation potential of ambient temperature travertine deposits. These relationships were examined using scanning electron microscopy and Raman microspectroscopy.Electronic supplementary material The online version of this article

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Actualistic Taphonomy of Cyanobacteria: Implications for the Precambrian Fossil Record

Cited by 159 publications

References 27 publications

Experimental taphonomy of giant sulphur bacteria: implications for the interpretation of the embryo-like Ediacaran Doushantuo fossils

Experimental taphonomy of giant sulphur bacteria: implications for the interpretation of the embryo-like Ediacaran Doushantuo fossils

Eukaryotic organisms in Proterozoic oceans

Cyanobacterial Contribution to Travertine Deposition in the Hoyoux River System, Belgium

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