Late paleozoic climate revealed by coral fossil patterns

Unexpectedly, a peak was found in late spring, followed by a trough in midsummer, and another peak in late summer, after dividing the graph into four seasons. In addition, the first peak had a higher value than the second one. The authors call it the bimodal phenomenon of the growth line width (of warm-water indi- vidual coral fossils in the Late Carboniferous), for which the reason remains unclear. The Wilcoxon signed rank test, a commonly used nonparametric statistical test, was then used as a confidence interval analysis for such a bimodal phenomenon in the above figures. Its fundamental principle involves converting the difference between each paired sample into a signed rank and subsequently assessing whether a statistically significant difference exists between the two sample sets by comparing the sum of the signed ranks. One notable advantage of this method is its ability to accommodate small sample sizes and non-normally distributed data because it does not necessitate stringent assumptions about the data distribution [12]. Using a significance level of 0.05 and a sample size value of 20, with the Wilcoxon signed rank test, the values of the troughs of the DZ-30-16 and DZ-30-24 samples do not significantly Fig 2. Elements enter the bone from seawater through calcified fluids and the main factors of element content [10]. https://doi.org/10.1371/journal.pone.0290127.g002 PLOS ONE Late paleozoic climate revealed PLOS ONE | https://doi.org/10.1371/journal.pone.0290127 August 15, 2023 4 / 13