What are the characteristics of paleontological fossils?

Fossil remains, relics and active remains of paleontology preserved in rock formations. Fossil is the main research object of paleontology, which provides evidence for studying the life history of animals and plants in geological period. There have been records of fossils in ancient books in China, such as Ji Ran in the Spring and Autumn Period and Wu Jin in the Three Kingdoms Period, all of which mentioned the "keel" produced in Shaanxi, that is, the bones and teeth of ancient vertebrates; There is also a description of "stone fish" (that is, fish fossils) in Shan Hai Jing; There are descriptions of ancient insects in amber of Tao Hongjing during the Qi and Liang Dynasties in the Southern Dynasties. In Song Dynasty, Shen Kuo had a correct understanding of the origin of snail and mussel fossils and Wandu fish fossils. So far, the earliest bacterial fossils found are filamentous bacterial fossils from Walla Onna group in Australia 3.5 billion years ago.

Only a small part of the creatures that formed the conditional geological historical period adapted to the geological environment and were preserved as fossils: ① The creatures themselves must have certain hardware, such as shells and carapace of invertebrates, bones and teeth of vertebrates, trunks, leaves, spores and pollen of plants; (2) After the death of organisms, they must be quickly buried by sediments to avoid being destroyed by biological, mechanical or chemical actions; (3) It must undergo various petrochemical actions for a long time.

Research Significance From the end of 18 to the beginning of 19, W Smith of Britain established the law of fossil sequence according to the vertical distribution of fossils. Paleontologists have found that the higher the stratigraphic level, the more fossil categories it contains, and the more complex the morphological structure of fossils, reflecting the evolution law of biological categories from less to more, morphological structure from simple to complex, and from low to high.