Phillips T L, Peppers R A, Avcin M J, Laughnan P F
Science. 1974 Jun 28;184(4144):1367-9. doi: 10.1126/science.184.4144.1367.
Coal palynology and studies of petrified peat indicate major changes in coal-swamp floras and the botanical constituents of coal throughout Pennsylvanian time. The changes are the result of broad climatic shifts and local environmental factors. The most striking is the change from a lycopod-dominated flora to one in which tree ferns were the major element. This change occurred at the Desmoinesian-Missourian (Westphalian-Stephanian) boundary and is probably multicontinental in scope.
煤岩学和石化泥炭研究表明，在整个宾夕法尼亚纪时期，煤沼泽植物群和煤的植物成分发生了重大变化。这些变化是广泛的气候变化和局部环境因素造成的。最显著的变化是从以石松为主的植物群转变为以树蕨为主要成分的植物群。这一变化发生在得梅因期—密苏里期（威斯法阶—斯蒂芬阶）边界，其影响范围可能涉及多个大陆。
