Late paleozoic climate revealed by coral fossil patterns

and the sunshine duration. This finding suggests the growth line width of fossil corals can indi- cate the changes in day length. Therefore, the bimodal phenomenon of the growth line width of the warm-water individual coral fossils in the Late Carboniferous is positively correlated with the sunshine duration, and the climate of Shiqiantan in the Late Carboniferous is similar to that of North China, with an evident four-season variation, because these seasons and the climate in North China are derived from the obliquity of the ecliptic, indicating the obliquity of the ecliptic existed at that time, and the sample was located in a temperate zone. In addition, to form a temperate zone, the value of the ecliptic inclination must be less than 45˚. According to Williams’ high-inclination hypothesis [16], the Ediacaran period was during 635–590 Ma, and the ecliptic inclination was about 54˚. Considering the Late Carboniferous period of the sample was around 310 Ma, just between the present and the Ediacaran period, a simple median calculation can be performed, that is, the inclination of the ecliptic at that time may be around 38˚, which is less than 45˚. In the S4 File, the possible theoretical variation of solar radiation intensity in the temperate zone in the Late Carboniferous is calculated based on the ecliptic angle of the Late Carbonifer- ous at 38˚ assumed by Williams’research. The results are consistent with those obtained through specimen statistics. Fig 10. Schematic of the average monthly sunshine duration in Beijing (1981–2010).

https://doi.org/10.1371/journal.pone.0290127.g010 PLOS ONE Late paleozoic climate revealed PLOS ONE | https://doi.org/10.1371/journal.pone.0290127 August 15, 2023 10 / 13