Stromatolite fossils

Golubic, S. Stromatolites, fossil and recent a case history, in Biomineralization and biological metal accumulation (eds. Westbroek, P., de Jong, E. W.) p. 313, Dordrecht, Reidel Publ. Co.,... 

Golubic S. (1983) Stromatolites, fossil and recent, a case history. In Biomineralization and Biological Metal Accumulation (eds. P. Westbroek and E. W. de Jong). D. Reidel, Dordrecht, Germany, pp. 313—326. 

More controversial is whether there is evidence for former life in greenstone sediments. At present the much publicized carbon isotope evidence for life in the 3.8 Ga Isua succession (Rosing, 1999) is under severe scrutiny. This is discussed in some detail in Chapter 6 (Section 6.3.2.1). In contrast stromatolite fossils have been documented in greenstone belt sediments from about 3.5 Ga onwards, and sulfur isotope evidence from the Belingwe Greenstone Belt demonstrates that there were complex algal communities by 2.7 Ga (Grassineau et al., 2001 - see Chapter 6, Section 6.3). 

Stromatolites Domal concretions formed on the seafloor, primarily shallow waters, by microorganisms. These deposits represent the oldest unequivocal fossilized remains of life on Earth. 

The time period in which prebiotic synthesis of organic compounds took place is frequently misunderstood. The earth is 4.5 x 109 years old, and the earliest fossil organisms known, the Warrawoona microfossils and stromatolites, are 3.5 x 109 years old.10 The difference is 1.0 x 109 years, but the time available for life to arise was probably shorter. It probably took a few hundred million years for organisms to evolve to the level of those found in the Warrawoona formation. In addition, if the earth completely melted during its formation, then the time available would be further shortened by the time needed for the earth to cool down sufficiently for organic compounds to be stable. 

Awramik, S.M., Schopf, J.W., Walter, M.R. (1988). Carbonaceous filaments from North Pole, Western Australia. Are they fossil bacteria or ancient stromatolites A discussion. Pre-Cambrian Research, 39, 303-309. 

Boon, J. J. Tracing the origin of chemical fossils in microbial mats Biogeochemical investigations of Solar Lake cyanobacterial mats using analytical pyrolysis methods, in Microbial mats Stromatolites (eds. Cohen, Y., et al.) p. 318, New York, Alan R. Liss Inc. 

Krumbein, W. E., Brehm, U., Gerdes, G. et al. (2003). Biofilm, biodictyon, biomat, microbialites, ooolites, stromatolites, geophysiology, global mechanisms, parahistology. In Fossil and Recent Biofilms A Natural History of Life on Earth, ed. W. E. Krumbein, D. M. Paterson G. A. Zavarzin. Kluwer Academic Publishers, Dordrecht, pp. 1-27. 

Fig. 16.8. Warsteia mycelia. (a) Fossil fungal mycelium in a chert/ ferrugenous stromatolite from a Tertiary deep karst environment from a limestone quarry of Warstein (Rhenish Massif, NW Germany). The stromatolite structure is caused by dense portions of hyphae filaments possibly resulting from seasonal ecological variation. The entire mycelium structure exhibits similarities with the fungal taxon Papulaspora. (b) Detail of the Papulaspora mycelium with conidia or chlamydospores.

Riding R. (1977) Skeletal stromatolites. In Fossil Alga Recent Results and Developments (ed. E. Flugel). Springer, Berlin, pp. 57-60. 

Most of the discussions relating organic activity to the origin of banded iron formations have centered on three areas (1) the presence of fossil microorganisms in cherts from banded iron formations (2) the similarities between laminations in banded iron formations and modem algal and bacterial stromatolites and (3) role of photosynthesis in the evolution of oxygen in the ocean and atmosphere, and consequently in the origin of banded iron formations. 

When did LUCA give rise to her diverse offspring Cells resembling modern prokaryotes date back 3.5 billion years, to the stromatolites in south-western Australia, as described in Chapter 3. The first signs of eukaryotic cells, the biomarkers of membrane sterols, date to about 2.7 billion years ago. The first unequivocal eukaryotic fossils are found... 

Figure 12-4 will now be discussed in more detail. The record of reduced carbon in sedimentary rocks and the associated, 3C/I2C isotope shift date back to the oldest deposits of 3.5 Gyr ago, and even further if one makes allowance for the metamorphic alterations of the still older Isua formation (see Fig. 11-2). The biological origin of the isotope shift has been convincingly demonstrated, as reviewed by Schidlowski et al (1983). The implication that life had been in full swing 3.5 billion yr ago is supported by several lines of fossil evidence stromatolites, microfossils, and banded iron formations.

Stromatolites are the commonest and most conspicuous fossils (Walter, 1976). They consist of bun-shaped or columnar, laminated structures, usually in limestone deposits since they are essentially indistinguishable from modem analogs forming today by colonies of blue-green... 

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