中国中生代拟合囊蕨属Marattiopsis(Marattia)的多样性和地质地理分布

FOSSIL RECORDS OF MARATTIOPSIS/MARATTIA(MARATTIALES)IN THE MESOZOIC OF CHINA:DIVERSITY,AND GEOGRAPHIC AND GEOLOGICAL DISTRIBUTIONS

拟合囊蕨(Marattiopsis)是蕨类植物门中较原始的厚囊蕨纲莲座蕨目合囊蕨科的一个化石属,是中生代植物群落中的重要组成分子。由于与现生植物形态相似,部分含繁殖器官化石标本常被归入现生合囊蕨属(Marattia)。尽管Marattiopsis和Marattia的使用一直存在争议,但传统上前者多用于裸羽片标本,而实羽片标本则多使用现生属名。然而,最近分子证据表明Marattia是一个并系类群的属,原有定义有所改变,因此,仅Marattiopsis属名应该保留并使用于化石标本。中国中生代的拟合囊蕨属(合囊蕨属)植物共计9种,其时空分布显示:该属在晚三叠世出现,并且分异度达到顶峰,但仅分布于华南;早侏罗世多样性大幅降低,但产地数量略有增长,并从华南扩散到华北;中侏罗世分异度和产地数量急剧衰退,仅在东北有少量残存;晚侏罗世至整个白垩纪,完全消失。本文认为拟合囊蕨多样性变化和时空分布模式与古气候和古地理综合效应密切相关:晚三叠世至早侏罗世炎热、湿润的气候条件有利于拟合囊蕨的发生和发展;中侏罗世以后逐渐温凉、干燥的气候大大缩减了该属的生存空间,并最终导致其绝灭。

Marattiopsis is a fossil genus the Order Marattiales of Eusporangiopsida of important component worldwide. Due to the between fossil and that belongs to the Class pteridophytes. It is an of the Mesozoic floras morphological similarities extant plants, both Marattiopsis and Marattia have been applied to describe fossil specimens. Although it has long been debated, Marattiopsis was used traditionally for sterile specimens, whereas Marattia was used for fertile specimens. Recent molecular evidence indicates that Marattia is a paraphyletic genus, and should be abandoned, thus, only the genus Marattiopsis should be conserved for fossils. Analysis of the tempo-spatial distribution of Marattiopsis （Marattia） in the Mesozoic of China shows that it firstly appeared during the Late Triassic and reached its maximum in both diversity and distribution, but only distributed in southern China; then it was reduced gradually in diversity, but the number of localities increased slightly and extended to northern China during the Early Jurassic. The diversity and location of the genus declined sharply during the Middle Jurassic, and only occurred in Northeast China. Since the Late Jurassic, the genus completely disappeared from the Mesozoic of China. The pattern of the tempospatial distribution of Marattiopsis is likely the result of combined effects of the palaeoclimatic and palaeogeographic changes. The hot and humid climate during the Late Triassic and Early Jurassic is in favour of the development and progression of the genus; cool and dry climate after Early and Middle Jurassic greatly reduced the survival of this plant group, and eventually led to its complete extinction from the Mesozoic in China.