Australia, stromatolites

Plate IB, Outcrop cross-section of 1,9 Ga stromatolites exposed in Duck Creek Gorge, Western Australia, Stromatolites nucleate as isolated individuals then grow upward and laterally, bridging to adjacent individuals to form massive reefs. Note new stromatolite growing on a substrate of old stromatolites in upper right. Cross-sections show same bulbous, top-heavy form seen at Shark Bay. Hammer handle 25 cm in length (photo by author),... 

Walter, M. R., Golubic, S-, and Preiss, W. V. Recent stromatolites from hydromagnesite and aragonite depositing lakes near the Coorong Lagoon, South Australia. J. Sed. Petrol. 43, 1021-1030 (1.973). 

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. 

Buick R., Dunlop J. S. R., and Groves D. I. (1981) Stromatolite recognition in ancient rocks an appraisal of irregularly laminated structures in an Early Archean chert-barite unit from North Pole, Western Australia. Alcheringa 5, 161-181. 

Glaessner, M.F., Preiss, W.V. and Walter, M.R., 1969. Precambrian columnar stromatolites in Australia morphological and stratigraphic analysis. Science, 164 1056—1058. 

Walter, M.R., Goode, A.D.T. and Hall, W.D.M., 1976. Microfossils from a newly discovered Precambrian stromatolitic iron formation in Western Australia. Nature, 261 221—223. 

Warren, J.K. (1982) The hydrological significance of Holocene teepees, stromatolites, and boxwork limestones in coastal salinas in south Australia. J. sediment. Geol., 52(4), 1171-1201. 

A weathered outcrop with conical stromatolites from the Tooganinnie Formation (McArthur Group), Northern Territory, Australia. Dated at 1.6Ga. A cm scale is shown at the left (courtesy William Schopf). 

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 1-15. Trendall Pilbara stromatolite, Western Australia, 3800 Mya Raman spectroscopic evidence for protective biochemicals, carotene and porphyrin, produced in a protected niche...

Walter, M. R., R. Buick, and J. S. R. Dunlop (1980). Stromatolites 3400-3500 Myr old from the North Pole area, Western Australia. Nature 284, 443-445. 

Plate 14JC. Outcrop cross-section of2.7Ga stromatolites exposed near Redmont, Western Australia. See Plate IB caption. Hammer handle 35 cm in length (photo by author). 

Ga (Schopf 1992), but these early Archean occurrences are controversial (Buick 1991). Conical and branched pseudocolumnar stromatolites occurring in 3.46 Ga carbonates and silicified carbonates of the Warrawoona Group, Western Australia were recently described (Hofman et al. 1999). Hoffman et al. concluded that microorganisms were indeed involved in the accretion of these stromatolites. They also surmised that microbial phototaxis might have played a role in shaping them, but concluded that such evidence for the role of photosynthetic biota is not yet definitive. 

Hofman HJ, Grey K, Hickman AH, Thorpe RI (1999) Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia. Geol Soc Am Bull 111 1256-1262 Holland HD (1984) The Chemical Evolution of the Atmosphere and Oceans. Princeton University Press, Princeton, NJ... 

Coshell, L., M. R. Rosen K. J. McNamara, 1998. Hydromagnesite replacement of biomineralized aragonite in a new location of Holocene stromatolites. Lake Walyungup, Western Australia. Sedimentology 45 1005-1018. 

Mediterranean Sea the cyanobacterial stromatolits of Western Australia) that does not necessarily mean that their individual cells were immortalized (see in the text) or are they living in a biological entity free of senescence, but different from malignant transformation (Rachel Sussman The Oldest Living Things in the World , University of Chicago Press, 2014). 

Stromatolites can still be found in isolated spots around the world. The best known may be at the hypersaline Shark Bay, Australia, where dark footstools rise from the water like mushrooms. These are the same kind of mats as seen in fossils. Once they were successful enough to cover the globe, but now they hang on in distant, extreme places where other hfeforms can t compete. It s a very low-key Jurassic Park (Archaean Park, perhaps ). 

The sequence may have started with carbon chains acting as umbrellas. To see these colors in action, start at Lake Hiller, which sits southeast from the Shark Bay stromatolites in Australia. The lake is surrounded by green forest and sits near the blue ocean, which only serve to highlight the water s bright pink color. Not slightly pink or squint at sunset and it looks pink, but Bazooka-bubble-gum princess-birthday-party pink. 

Cyanobacteria have great ecological importance because they occur in all the biotopes, both marine and terrestrial. Although approximately 7500 species have been described, it would seem that there are only about 200 that are distinct, and among those it has been estimated that 75% are marine. The oldest fossils of cyanobacteria -called stromatolites - date back 3.5 billion years and are frequently found on the shores of old Precambrian platforms (Australia, Canada, the USA). The abimdance of stromatolites is one of the arguments suggesting that cyanobacteria are our true ancestors (Groves, Dunlop, and Buick, 1983 Halstead, 1984). 

---