Earliest record of megaphylls and leafy structures, and their initial diversification  

作　　者：HAO ShouGang XUE JinZhuang 

机构地区：[1]Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University

出　　处：《Chinese Science Bulletin》2013年第23期2784-2793,共10页

基　　金：supported by the National Natural Science Foundation of China(41272018 and 40830211)

摘　　要：Evolutionary changes in the structure of leaves have had far-reaching effects on the anatomy and physiology of vascular plants, resulting in morphological diversity and species expansion. People have long been interested in the question of the nature of the morphology of early leaves and how they were attained. At least five lineages of euphyllophytes can be recognized among the Early Devonian fossil plants (Pragian age, ca. 410 Ma ago) of South China. Their different leaf precursors or "branch-leaf complexes" are believed to foreshadow true megaphylls with different venation patterns and configurations, indicating that multiple origins of megaphylls had occurred by the Early Devonian, much earlier than has previously been recognized. In addition to megaphylls in euphyllophytes, the laminate leaf-like appendages (sporophylls or bracts) occurred independently in several distantly related Early Devonian plant lineages, probably as a response to ecological factors such as high atmospheric CO 2 concentrations. This is a typical example of convergent evolution in early plants.Evolutionary changes in the structure of leaves have had far-reaching effects on the anatomy and physiology of vascular plants, resulting in morphological diversity and species expansion. People have long been interested in the question of the nature of the morphology of early leaves and how they were attained. At least five lineages of euphyllophytes can be recognized among the Early Devonian fossil plants （Pragian age, ca. 410 Ma ago） of South China. Their different leaf precursors or ＂branch-leaf complexes＂ are believed to foreshadow true megaphylls with different venation patterns and configurations, indicating that multiple origins of megaphylls had occurred by the Early Devonian, much earlier than has previously been recognized. In addition to megaphylls in euphyllophytes, the laminate leaf-like appendages （sporophylls or bracts） occurred independently in several distantly related Early Devonian plant lineages, probably as a response to ecological factors such as high atmospheric CO2 concentrations. This is a typical example of convergent evolution in early plants.

关 键 词：叶结构 多元化 植物解剖学 早泥盆世 二氧化碳浓度 趋同进化 叶片结构 植物化石 

分 类 号：Q914[天文地球—古生物学与地层学]