Brief description of the formation of a fossil
These are the more or less complete remains of an animal or plant that have escaped decomposition after death.
This is a very rare event that can occur if the organism is buried rapidly. The parts that are best preserved are those that are already composed of minerals, such as shells, teeth, bones, etc.
One can preserve not only the parts of an organism, but also the traces of its activity, such as, for example, the footprints of dinosaurs or more simply the tunnels of marine organisms such as sea urchins, small crustaceans, etc….
The study of the history of organisms from death to their discovery as fossils is called taphonomy. Three basic stages are mainly distinguished in order of time:
- Death
- Burial
- Fossilization processes
The most common causes of death are: predation, suffocation, poisoning or more generally change in environmental parameters. These variations are related to factors such as significant changes in salinity, oxygen content and/or water temperature. Sudden events, such as floods or landslides, can bring in huge volumes of sediment in a relatively short time and cause nearby organisms to suffocate. When an organism dies, necrolysis processes begin, including possible disarticulation of skeletal parts. The latter is accelerated by the environmental conditions in which the organism finds itself.
In Italy, activities related to paleontology are subject to the Code of Cultural Heritage and Landscape, Legislative Decree No. 42 of January 22, 2004, which also regulates and regulates archaeological heritage.
Among the Assets considered to be subject to protection are also geo-paleontological sites, so research and excavations aimed at finding fossils from all Eras are delegated to the state. Research activity may also be authorized for universities and specialized institutes and museums.
Fossil searching and collecting, is it legal?
Collection or collection by private individuals, who have the duty to hand over to the competent authorities of the Territory, of fossils accidentally found in plowing or simple fortuitous discoveries is not allowed. Finders themselves are entitled to a “prize” in the case of discoveries of exceptional cultural interest.
The cataloging and documentation of paleontological heritage is taken care of by the
Central Institute for Catalogue and Documentation, which in recent years has developed the descriptive sheet of Paleontological Heritage, which is a standard for all scholars in the field.
Fossils of non-Italian origin, on the other hand, since they are not bound by the aforementioned law, can be freely traded, sold and handled without any problem, as long as they have been regularly introduced into our territory.
The fossils on display at the P.AR.C. Museum. of Genoni
The fossils displayed in the
halls of the P.AR.C. consist mainly of sea urchins, bivalves and gastropods, a few rare crustacean remnants such as small crabs or barnacles, and a small cephalopod specimen.
All of these animals have in life a shell or shell composed mainly of calcium carbonate (calcite and aragonite). The fossilization process involved here is called mineralization. The sediments that have enclosed our fossils for millions of years have, over this very long time, given rise to chemical reactions that have caused the calcite in the shells to recrystallize, keeping the outer shape virtually intact.
It often happens that due to special chemical and physical conditions the shell is dissolved and the organism’s footprints remain imprinted in the rock layer that covered it.
The plants found, consisting mostly of parts of branches, fragments of logs and pine cones, have undergone the process of carbonification. After rapid burial of the remains, the bacteria, in the absence of oxygen, cause the elimination of fluids and other organic compounds, and there is an enrichment of carbon, which is already naturally present in the body.
The study of fossils helps us reconstruct the environment, flora and fauna of the past.
Article by Geologist and PARC science director Luigi Sanciu