The aim of Paleontology is to study fossils, which are preserved remains of organisms from the remote past; in fact, fossils which had a time-limited diffusion but a wide geographical distribution are a good instrument for recognizing rocks from the same geological period, so they are called “guide fossils” and are fundamental for precise chronological rocks setting of date.
In this field the branch of knowledge that in particular studies animal fossils is called Paleozoology, while the counterpart for plant fossils is called Paleobotany.
Chemical and physical processes that led to fossils formations are known as Fossilization processes. Also fossils proof of vital activity, which is reflected in reworking of sediments and hard substrates by organisms, rather than the physical remains of the organism itself, make a positive contribution to this field and is studied by a branch of paleontology called Paleoichnology.
Thanks to Paleogeography, which studies fossils distribution into horizons, we can stabilize land and seas conformations, leading to a reconstruction of past times “geographical charts”.
Moreover, living being that during evolution had conserved they characteristics and didn’t undergo substantial anatomic modifications are called “Living Fossils”.
Thanks to a particular type of fossils called “climatic indicators” also Paleoclimatology allows to reconstruct climatic aspects of times past: in fact these are recognized as typical of each environment, such as cold or tropical seas.
Paleoecology reconstructs past habitat thanks to fossils which are contained in sedimentary rocks horizontal layers. In particular, fossils called “facies” here found are mandatory for original habitat reconstruction.
During fossilization processes, when the whole body or pieces of it are preserved without big composition or structure modifications we have the complete preservation. Otherwise mineralization is characterized by substitution of original organism component with minerals, which only allow to maintain general shape, even if in the best case this process allows to reproduce the smallest anatomy structure, the cell.
Model fossilization is generally found in those organisms whose parts of the body are particularly consistent, such as shell in shellfish, when sediments in which they are incorporated or have filled their cavity became cemented. Even if the organism disappear by solubilization, the internal or external morphological aspects are conserved, giving thus the “external” or “internal” model.
FOSSIL EXTRACTION TECHNIQUES
When fossils are guzzled in consistent rocks, physical cleaning of the sample is necessary, and after that the procedure is completed with chemical acid etching.
In the case of laminated rocks there is the separation of every thin layers with common tools.
“Inchorent rocks”, such as sands and clays, are analyzed on different meshes sieve size through washes to extract shells or other pieces.