被子植物的起源—以喜花虻类化石为据

ORIGIN OF ANGIOSPERMS BASED ON THE FLOWER LOVING BRACHYCERA FOSSILS

喜花昆虫在被子植物的起源和早期演化上起着决定性的作用。虻类化石中的许多类群都有访花习性，它们为研究被子植物的起源提供了独特材料。虽然最老的被子植物化石还没有发现，但是喜花虻类的爆发式出现，表示了被子植物出现的时间和地点。本文主要以欧亚大陆东部，特别是中国辽西的侏罗世虻类化石为材料，在功能形态分析和与现代类群作对比的基础上，证实了虻类是显花植物最原始的传粉类群之一。中国东北、哈萨克斯坦和西伯利亚晚侏罗世喜花虻类的发现表明当时至少有两种不同类型的花已经存在。虻类化石较高的演化水平和多样性显示被子植物群的分化还略早于晚侏罗世。东亚，特别是中国东北是被子植物的起源中心之一。

Anthophilous insects played a decisive role in the origin and early evolution of the flowering plants. The fossil Brachycera contain a wider variety of flower visitors, which provide unique material for studying the origin of angiosperms. Although no fossil remains of the earliest angiosperms has been found, the first appearance, especially explosive radiation of anthophilous short horned flies, undoubtedly indicated the time of the first appearance of the flowering plants and the place of their origin. This work has largely focused on the Late Jurassic Brachycera found from Eastern Eurasia continent, especially from Western Liaoning. Based on the analyses of functional morphology and comparison with modern taxa, all these facts show that the Brachycera were one of the most ancient pollinators of the flowering plants. The present discoveries of anthopilous fossil Brachycera from the Late Jurassic of NE China, Kashkstan and Siberia demonstrate that the flowers were in existence in the Late Jurassic and represented by at least two different types of flowers. The diversity and relatively high level of evolution of these fossil short horned flies suggest a differentiaion of the angiosperms group prior to the Late Jurassic. The east Asian, especially NE China, is one of the original place of the angiosperms.