1.- Mineralization
1.1 Recrystallization
1.2 Epigenization
2.- Carbonization
3.- Casting and Molds
3.1 Exterior
3.2 Interior
3.3 Against mold
Explanation:
The fossils, somatofossil, icnofossil, are formed after the remains of the body is buried. There are three forms of preservation, mineralization, smelting and molding and carbonization that preserve the remains for millions of years.
1.- Mineralization
They are processes in which bones and ichnofossils are formed. The remains of the body receive an addition of minerals or an alteration of the original minerals existing in the bone, which end up turning the remains practically into rock, with which it is known by petrification. Good examples are tree trunks, large bones and shells.
Within the mineralization we highlight two modes of fossilization that you can see below.
1.1 Recrystallization
The original organism is not preserved in its original material, the bone, for example, which is mostly replaced by some other mineral and the structure or shape of the fossil is partially modified.
1.2 Epigenization
This process is divided into two types.
The first, permineralization, occurs when the original material of the organism undergoes an addition of minerals that penetrate the bone, for example, leaving this petrified and heavier, since in addition to the original material the weight of the minerals added by time.
The other process is known as pseudomorphosis, where the original form of the organism is maintained but its material is completely replaced by another mineral.
2.- Carbonization
It occurs when there is a loss of volatile substances (oxygen, hydrogen and nitrogen mainly), leaving a carbon film. It is more frequent in structures formed of lignin, chitin, cellulose or keratin. This occurs when remains of plants or animals are crushed under a rock.
3.- Casting and Molds
They are negative impressions (it does not represent the organism as it really is, just an inverted mold) or positive (it represents the organism as it really is, that is, a copy), of parts of the organisms or their icnofossils. The molds are formed in 3 types.
3.1 Exterior
Forms a negative impression of the organism, such as the skin of an animal or the surface of a shell. The organism is covered in its outer part by a type of material, such as mud, for example, and its body over time remains the format of the organism in the mud that turns into rock, however for this to occur it is necessary that the remains have some surface with indentations, holes, irregular texture and that is somewhat resistant, so that the material that will form the impression can penetrate there and solidify. See the outer mold of a shell below.
3.2 Interior
Forms an internal impression of the organism, commonly occurs in shells. The mold is negative and is formed when mud or any other material penetrates inside the holes and into the rest of the animal and it ends up curdling. The body decomposes and a mold is left of the inside of the shell or of the organism in question.
3.3 Against mold
It forms a COPY of the original organism, but it is more difficult to produce naturally, since for the counter mold to be made it is necessary that first an internal or external "first mold" of it be made. This mold is filled with some material and would form a copy of the organism that formed the "first mold."
