Temperature is the most influential environmental factor for biological growth. It not only controls the latitudinal distribution range of organisms, but also determines the vertical distribution range of marine and terrestrial organisms. Therefore, organisms can be divided into tropical organisms, temperate organisms, and arctic organisms, as well as warm-loving organisms and cold-loving organisms, and even hot spring organisms and cold spring organisms. For example, when coral fossils are found, no matter where they are found, it indicates that the area was once in a warm marine environment. The impact of temperature is also recorded in biological skeletons or other hard fossils. The width and narrowness of skeletal growth rings are markers of summer and winter seasons or day and night lengths. More interestingly, the composition of shells or vertebrate teeth fossils also clearly records changes in temperature. The most typical temperature parameter is the ratio of oxygen isotopes O-18 to O-16. When the content of O-16 in skeletal fossils is high, it indicates that the temperature rose at that time, and vice versa, it indicates that the temperature fell. In addition, elements such as manganese and strontium can also well indicate seasonal changes in temperature.
In addition to environmental temperature, the temperature of rocks can also be determined by fossils. There is a kind of fossil called conodonts, which are fossilized pharyngeal teeth of a type of worm-like animal. Their colors vary from white, amber to black. Different colors are related to the degree of organic matter deterioration in conodonts, and the degree of organic matter deterioration is related to the temperature of rocks, burial depth, and time. Therefore, conodonts can be used as a "thermometer" for rocks and serve as a reference in oil exploration work.