Late paleozoic climate revealed by coral fossil patterns

was located at higher latitude in the Northern Hemisphere at that time. They presented the biological zoning maps of corals and bivalves in the Middle and Late Carboniferous period. The location of Shiqiantan in Xinjiang Province is shown by Ts in Fig 9. The key findings of this short review are as follows: Shiqiantan belonged to a higher-latitude area in the Northern Hemisphere at that time. The sunshine duration at this location during the year changed with the seasons according to the current obliquity of the ecliptic. The increasing sunshine duration from January to April corresponded to longer sunshine duration during winter to spring in the Northern Hemisphere. At the end of summer, the days gradually shortened in the Northern Hemisphere due to seasonal changes, thereby gradually decreasing the number of monthly sunshine. The above conjecture can be verified by the sunshine dura- tion in North China when the location is related to present-day North China. Therefore, according to the monthly (annual) sunshine duration chart in the surface cli- mate diagram of China (1981–2010) provided by the China Meteorological Data Service Cen- ter, the sunshine duration of January to December was obtained, as shown in Fig 10. Chen [15] et al. established the mean sunshine duration time series of the North China Plain based on the sunshine duration data of 50 stations in the North China Plain provided by the China Meteorological Data Service Center. The monthly sunshine duration in descending

order is May (252.8 h), June, April, August, July, March, September, October, November, Jan- uary, February, and December (166.1 h). This result is consistent with that in Fig 10. The results are very exciting. The variation of the monthly sunshine duration chart is rela- tively consistent with that of the coral growth line width, which clearly supports the positive correlation between the daily growth line width of individual corals in the Late Carboniferous Fig 7. Width statistics of growth lines on fossil epitheca, in sequence. https://doi.org/10.1371/journal.pone.0290127.g007 PLOS ONE Late paleozoic climate revealed PLOS ONE | https://doi.org/10.1371/journal.pone.0290127 August 15, 2023 8 / 13