How are fossils classified?

The classification of fossils can be carried out according to various standards. The traditional classification is to distinguish fossils according to their preservation type or size, but for the protection and management of paleontological fossils, we should distinguish the value and importance of different fossils.

According to the preservation types of fossils, they can be divided into solid fossils, die-casting fossils, trace fossils and chemical fossils. Solid fossils are all or part of biological remains preserved by petrochemical action, such as the familiar dinosaur bones (Figure-1 1) and mammoth teeth. Die-casting fossils are impressions and molds of biological remains preserved in rock formations, such as the common wolftail fish fossils in the Kistler market (Figure-12). Trace fossils are traces and remains left by paleontological activities preserved in rock strata, such as dinosaur eggs, dinosaur footprints (Figure-13) and feces. Chemical fossil is a special kind of fossil formed by the residual organic components in the stratum after the soft part of biological organic matter was destroyed in geological history, some of which can form important mineral resources, such as coal, oil and natural gas.

Figure 1- 1 dinosaur bones-solid fossils in Zigong dinosaur museum, Sichuan province (photography/Zhao Hongshan)

Figure 1-2 Wolf fin fish fossils-die casting fossils (photography/Zhao Hongshan)

Figure 1-3 dinosaur footprints-trace fossils (photography/Luo Tuanjie)

According to the size of fossils, they can be divided into macroscopic fossils and microscopic fossils. Fossils that can be directly studied by conventional naked eye observation are called large fossils. Some fossils are tiny parts or organs of organisms, which are generally difficult to identify with the naked eye, and are called microfossils. Among microfossils, there is a kind of fossils below 10 micron, which must be observed and studied by means of electron microscope or scanning electron microscope. It is called nannofossils.

According to the importance of biological evolution and biological classification, paleontological fossils are divided into key protected fossils and general protected fossils. Fossils with important scientific research value or a small number should be listed as key protected fossils, including: type specimens of named fossil species; Preserve intact or relatively intact solid fossils of vertebrate paleontology; Large or concentrated footprints of higher plants, invertebrates and vertebrate paleontology; Other paleontological fossils that need to be protected as determined by the competent department of land and resources of the State Council. Specially protected paleontological fossils can also be subdivided into first-class protected fossils, second-class protected fossils and third-class protected fossils. See Chapter 5 for their classification basis.