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 , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

, in shallow

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, 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 t ...

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 transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

Microbial mat A microbial mat is a multi-layered sheet or biofilm of microbial colonies, composed of mainly bacteria and/or archaea. Microbial mats grow at interfaces between different types of material, mostly on submerged or moist surfaces, but a few surviv ...

s, 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 or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

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 The eukaryotes ( ) constitute the domain of Eukaryota or Eukarya, organisms whose cells have a membrane-bound nucleus. All animals, plants, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of li ...

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