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The taphonomy is the branch of the paleontology which is dedicated to the study of fossils and the processes involved in their formation. This transformation from living organisms to fossils is what is known as fossilization and depends on certain circumstances for its success; so animals or plants do not always leave fossil records. Given the complexity of the phenomenon, doubts may arise about how a fossil is formed exactly or whether there are different types of fossilization and what their characteristics are.
If you are interested in knowing more, continue reading this interesting article by Green Ecologist about the different types of fossilization and their characteristics where you can find out how fossils are preserved, as well as some examples of types of fossils according to their fossilization process.
What are fossils and how are they formed
Fossils are plant or animal remains that have been dead for a long time, which have not become rotten and which, over the years, have become one more component of the earth's crust. His study, through the geological dating rocks and phenomena at the planetary level, allows sort the fossils in geologic time, which is the time elapsed since the Earth was formed until today.
The fossil formation process, called fossilization, is considered a complex natural cycle that depends on: the lack of oxygen, the rapid burial of organisms (generally in hydric sediment) and the paralysis of the decomposition process.
Obviously, there are fossilization processes in which changes in the composition and structure of organisms are minimal or scarce, so we speak of unaltered fossils (inclusion, mummification, freezing); however, there are also altered fossils (permineralization, carbonization, replacement) in which there is a drastic structural or chemical transformation. As indicated, fossils can be formed in a number of ways. It is briefly explained below how fossils are classified according to their formation.
Types of fossilization according to the geological process
These are the 3 types of fossilization according to the geological process:
Permineralization or petrification
Is he fossilization process whereby the hard parts of an organism, made up of porous material and cavities, are covered by runoff water loaded with dissolved ions (silica, calcium carbonate, phosphates, sulfates, iron oxide) that occupies its interior, which can cause the disappearance of the internal structure and the formation of crystals that preserve the surface structure of the body. This type of mineralization, similar to the foundation process, is very common in dinosaur fossils. If you are curious about these creatures, here you can learn about herbivorous dinosaurs: names, types, characteristics and pictures and here about carnivorous dinosaurs: names, types, characteristics and pictures.
Printing or compression fossilization, very common in plants, occurs when the remains of organisms are subjected to high temperatures or high pressures exerted by rocks and other edaphic and subsoil materials.
Inclusion
This fossilization process occurs when organisms become trapped in conservative materials or environments. Depending on the conditions, they can be distinguished 3 types of embedding or embedding:
- Gelling or freezing: it is a fossilization more typical of glacial areas. The glaciations that have occurred on our planet have left numerous organisms preserved in whole (Siberian mammoth) or in part (mammoth hair in permafrost), buried under large layers of ice.
- Mummification: Considered a pause in the disintegration process, without becoming a real fossilization, it originates after a massive loss of fluids in the organisms, which prevents the putrefaction of the organisms.
- Trapped in amber or tar: amber, which is a fossilized plant resin, preserves the external structure, but not the internal one, of organisms. Inside of fossilization in amber it is common to find insects, spiders, frogs and lizards. With pitch, which is a very viscous hydrocarbon, the same thing happens. In general, Pleistocene fossils stand out, such as mammoths, mastodons, wolves, bison, saber-toothed lions, etc.
Types of fossilization according to the physical process
These are the 5 types of fossilization according to the physical process:
Dislocation
Disarticulation, which involves the separation of the components of the remains of organisms, can take place during the processes of bioturbation, compaction of the sediment or by phosyldiagenesis.
Fragmentation
Fragmentation is a destructive process that is easy to identify in fossils, as it consists in their breaking, caused either by physical impacts or by the action of living beings.
Bioerosion
This process is very common in marine fossils and consists of the elimination or decomposition of materials from a hard substrate by the action of organisms. In these ecosystems, bioerosion is caused mainly by mollusks, sponges, crustaceans and fish, among others.
Abrasion
It consists of the erosion or wear of organic remains that end up being fossils through friction with water currents and also with air currents.
Corrosion
Corrosion is triggered by factors that promote chemical degradation and alter the surface of the fossil record.
Types of fossilization according to the chemical process
These are the 5 types of fossilization according to the chemical process:
Carbonation
This type of fossilization is very common and consists of the replacement of hard organic remains by calcite, a mineral composed of calcium carbonate. Since the skeleton of corals is made up mostly of this material, fossilization through this process takes place rapidly.
Carbonification
East fossilization process which consists of the substitution of organic components for carbon, characterizes the carboniferous period, and is very common in plant remains and arthropods, due to its cellulose and chitin content, respectively.
Silicification
Sometimes silica is derived from chemicals that allow fossilization, as is the case with chaldedonia. The most common fossils in this process they are foraminifera, echinids, ammonites, gastropods and brachiopods.
Pyritization
In pyritization, the organic parts of shells and skeletons are replaced by marcasite and pyrite, two types of iron sulfides, a product of the combination of sulfuric acid generated by the decomposition of marine organisms under anoxic conditions with the iron present in seawater. .
Phosphating
In this process, very common when there is a certain accumulation of vertebrate remains, the calcium phosphate present in bones and teeth, together with the calcium carbonate in the sediment, favors the formation of fossils.
Types of fossilization according to whether the organism is present
In addition to the types of fossils mentioned below, through the paleontological footprint it is possible to obtain information from organisms when they were alive. The ichnofossils (fossilized footprints or fossil footprints) it is possible to find them indoors, which is known as coprolites, or on the surface of the stratum, as is the case of the icnites of dinosaurs.
Bodily
In this type, the fossil preserves its skeleton to a greater extent. We have the example of the frozen mammoth and one closer to us, which we have surely seen at some time, the shells.
Mold
It is the impression or the filling of the fossils after dissolving their organic parts. If we see the shape printed, we speak of an external mold; On the contrary, if we observe that a tracing product of the internal filling of the organism has formed, we speak of an internal mold.
Fossil substances or chemical fossils
Fossil substances or chemical fossils can be found in geological materials, which turn out to be substances that were generated by the activity of extinct organisms and were trapped there.
Now that you have learned all this about how they are formed and what is the process of preserving fossils in a natural wayYou may be interested in continuing to learn more about what living beings and the planet were like so many millions of years ago. If by now you have learned enough about types of fossilization and their characteristics, Dare to discover which is the oldest fossil in the world.
If you want to read more articles similar to Types of fossilization and their characteristicsWe recommend that you enter our Nature Curiosities category.
Bibliography- Zugasti, F. I. G. (2008). Taphonomic analysis in archeomalacology: the example of the shells of the Cantabrian region. Krei, (10), 53-74.
- Fernández López, S. R. (2000). Paleontology Department. Faculty of Geological Sciences. Complutense University of Madrid. Taphonomy Topics: https://eprints.ucm.es/id/eprint/22003/1/087_00_Temas_Tafonomia.pdf
