Stromatolites. Dissemination 79th
In Disclosure 33 point 8 we published: "3.6 billion years ago appear the first bacteria and stromatolites which we have certainty as complete fossils". In this Divulgacion 79, we present a microscopic picture of a fossil stromatolite from Greenland dated between 3850 and 3600 million years.
Stromatolites with coelacanths 400 million years (see photo of the week 07/04/2015) Cycas revoluta to 300 million years and Ginko biloba 270 million years are the beings who are not extinct since appearance, being able to find these days, therefore, equal to their living fossil specimens. Stromatolites are by definition (stroma = sheet; lithos = stone) laminated structures that grow attached to the substrate. Since the beginning of the construction of a stromatolite, microorganisms are stratified into micro-ecological niches, as needed. For example, anaerobic bacteria usually live below the surface, and anoxic conditions where not much light reaches; cyanobacteria are usually in the surface where light reaches more and more room to grow. Microbes are growing along the sediment that is solidifying. Other organic waste can be buried as part of rolling. New cyanobacteria recolonize the surface and so on higher layers are formed. . The buried organic matter is decomposed with time, leading to gaps be filled with sediment, which may confer the stromatolite a porous texture.
The massive presence of stromatolites between 2500 and 1000 million years increased the oxygen content of the water and atmosphere, giving rise to a major ecological change on the planet.