Notes from UCMP

Hadean (4.5-3.8 bya) not a geological period

Archean (3.8-2.5 bya) only bacteria; bacterial microfossils 3.5 bya; also stromatolites;
{chemical fossils, pigments}{Bitter Springs chert}{asthenosphere, lithosphere}

Proterozoic (2.5 bya- 543 mya) formation of continents; oxygen atmosphere (cyanobacteria); first eukaryotic fossils( 1.8 bya) {oxidative respiration}{llano uplift, Texas}

Sties:
Bitter Springs (chert)Ediacara HillsMistaken Point, NewfoundlandNopah RangeWhite Sea---------Ediacaran fossils of CanadaNamibia-------Llano UpliftPrecambrian in Calif.

Paleomagnetism


Stromatolites began to decline in abundance and diversity about 700 million years ago. A popular theory for their decline (though certainly not the only possible explanation) is that herbivorous eukaryotes, perhaps including the first animals, evolved at about this time and began feeding extensively on growing stromatolites. Stromatolites are rare fossils after about 450 million years ago.
The oldest fossil that may represent a macroscopic organism is about 2.1 billion years old. Several types of fossil that appear to represent simple multicellular forms of life are found by the end of the Paleoproterozoic. These fossils, known as carbon films, are just that: small, dark compressions, most resembling circles, ribbons, or leaves; they are most common and widespread in the Neoproterozoic (Hofmann, 1994). Some resemble seaweeds and may represent eukaryotic algae; we know from independent evidence that red algae and green algae appeared in the Proterozoic, probably over 1 billion years ago.
There are tantalizing hints from trace fossils and molecular biology that animals may have appeared as much as 1 billion years ago.
The time from 600-650 million years ago to 543 million years ago, known as the Vendian period, saw the origin and first diversification of soft-bodied organisms known collectively as the "Vendian fauna" or "Ediacara fauna" (after the Ediacara Hills of southern Australia, where the first abundant and diverse fossils of this kind were found).