How did paleontological fossils form? What are the chances?

The biological remains and their traces of life activities in geological history have gone through a long geological age after being buried by sediments. With the diagenesis of sediments, the biological remains or remains buried in sediments are transformed by physical and chemical actions (often replaced and filled by minerals) and finally form fossils.

The conditions for the formation of fossils are harsh. First, the organism itself must have a hard part that is easy to preserve fossils, and the minerals that make up the hard part are relatively stable in the process of diagenesis and petrochemical, and are not easy to decompose. Second, the environmental conditions after death also affect the preservation of fossils. Fossils can only be formed if the dead creatures are buried quickly, and the bodies are not swallowed by other animals and destroyed by external forces. Third, there are post-preservation conditions, and the biological remains buried in sediments have to undergo various geological transformations in the long geological history, including compaction and consolidation diagenesis of overlying thick sediments, crystallization metamorphism under geothermal action, structural deformation and groundwater replacement. In such a complicated geological process, most creatures and their remains are destroyed, and only a few can be preserved as fossils. It can be seen that the fully excavated paleontological fossils are only a tiny part of the biological world that once lived on the earth. Although the current technology can not accurately calculate the formation probability of fossils, it is not an exaggeration to describe them as "one in ten thousand".