The Bitter Springs preservational mode is the preservation of microorganisms in

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

, in shallow

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

waters.

Taphonomic processes

Silica is emplaced around the organisms very rapidly, before their cells can even collapse; the strong silica is able to withstand great pressures and preserves three-dimensional detail even after

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

. Microbial mats, as they decayed, acted as nuclei for silica precipitation.

Occurrence

The preservational mode is only present in the

, and is restricted to shallow or tidal waters. After this point, organisms such as

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

s extracted silica from the oceans in order to construct

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...

s (skeletons), with the result that the surface oceans no longer became supersaturated with respect to silica when evaporation condensed the mineral.

Constraints

Because microbial mats and shallow, supersaturated seas were necessary for the formation of this form of deposit, larger

eukaryotic organism Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

s could not survive in the regions in which these deposits were formed; hence the record is mainly restricted to bacteria.

References

Fossilization Proterozoic fossil record {{paleo-stub