TAPHONOMY: HISTORY, PRESERVATION AND ALTERATION OF FOSSILS - BIOLOGY - 2025

The tafonomía is a specialty of paleontology who is responsible for studying the process of fossilization of a body after death. The possibility of determining everything that happened around the fossil is raised from the death of the animal until its later discovery.

It is associated with the study of preservation that determines to what degree the fossil was altered by the environment and the changes that occurred until it was found. Thus, taphonomy allows answering questions in areas such as paleobiology and palaeoecology.

Shell fossils in stone. Image by PublicDomainPictures from Pixabay

There are two fundamental concepts to understand the points between which taphonomy performs: fossilization and conservation status. The first refers to the transition of an organism from its living state to its fossil state, a procedure that gives rise to the formation of what is known as fossil deposits. In turn, the state of conservation is the point at which the fossil is found when discovered.

All the effects that changes in the environment could have generated in a fossil provide clues about what the environmental conditions of its time were like.

History of taphonomy

There have been many attempts to describe taphonomy in a more concrete way, which also has to do with its point of establishment as a science. The best known definition was provided by the Russian paleontologist Efremov in 1940. He established taphonomy from the beginning as “the study of the transition of living beings from the biosphere to the lithosphere”.

However, over time, the discipline was expanded in order to find meaningful explanations, beyond taking the fossil only as an element of chronological and evolutionary importance.

This is how taphonomy would also seek to explain the entire process of fossilization and formation of a fossil deposit and how the changes affected the remains found.

Part of the 19th century it was in contact with taphonomy without having yet defined itself as a specialty. There was a tendency to understand the reasons that led the fossils to their particular state of preservation.

The taphonomic history of fossils

A preserved fossil can be a great source of information about Earth's past. You can talk about behaviors of living things, composition of areas and even details about the climate and the soil in which they are found.

There are some important concepts that are taken into account to address the changes generated in a fossil, that is, its taphonomic history.

To talk about the taphonomic history of a set of bone fossils, it must be known that this in turn implies an ordered series of events:

1- Taphonomic agent: this refers to the physical cause that could have generated modifications in the fossil.

2- Taphonomic process: which would explain the way in which the agent caused the modification.

3- Taphonomic effect: being the final result produced in the modification.

Alteration of fossils

There are many external processes that can affect or modify a fossil. Abrasion, chemical processes in the land and even carnivorous animals could have generated changes in the remains found.

For example, in the case of carnivorous animals, they are capable of producing perforations, fractures and marks generated by teeth in a fossil. They could also be the cause of the absence of parts in a bone structure, since many animals usually transport their hunted prey to certain sites.

The burial form is also a detail that can help to identify the damage before and after the burial until the burial. Mineral absorption is another cause of alterations, especially in the coloring of the fossil. Through this, the materials used for a burial can be known if they have been made by humans.

The influence of elements such as water or fire can also be identified in a fossil. Regarding the first, it can be detailed with traces of erosion. For its part, fire is the least common factor of alteration, however, it can give information about some incendiary event of the past.

The taphonomic effects can be observed both at a macroscopic and a microscopic level and depend on the type of taphonomic agent that has been in contact with the fossil.

Forms of preservation

Preservation studies alterations in fossilized materials at different levels. It can range from a large-scale point of view to a molecular level. It works as a study supplement that is closely linked to taphonomy.

Exceptional Preservation Fossil Example

Image by kkorvin from Pixabay

The fossilization process largely depends on the way in which some remnant of a living organism reaches a state of preservation after death. There are two known forms of preservation:

Unaltered fossils

The unaltered fossils or exceptional preservation, which are those in which the changes have been minimal at the level of the structure of the organism and its composition. These types of finds can even contain traces of organs, soft tissue, feathers, and more.

Altered fossils

In altered fossils it is common that there are no more than just bones. Besides, there are usually alterations in the structure of the fossil and changes generated by chemical reactions.

Some alterations can be permineralization (the material is impregnated with salts) and replacement, which occurs when the structure of the fossil is dissolved and replaced by a material that remains in place as a mold.

New approaches

As paleontology develops, the branches of study and the number of specialties grow. This is how new approaches have emerged, such as the case of taphonomy, which allow the discovery of life forms from prehistory and a better understanding of the evolution of the planet.

The preservation and taphonomic history of a fossil clarifies the panorama of the possible changes that the Earth has gone through throughout the ages.

References

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