中侏罗世枫杨属果序化石的发现及意义

华北燕辽地区中侏罗世植物群中的一段枫杨属Ｐｔｅｒｏｃａｒｙａ果序化石，其形态、结构及习性，与现代枫杨属枫杨组Ｓｅｃｔ．Ｐｔｅｒｏｃａｒｙａ各种的果序酷似．这一事实表明：中侏罗世的枫杨属已具有现代水平，而自中侏罗世至现代，该属变异甚微；该属在中侏罗世之前已经过长期演化．这与研究同一侏罗纪化石植物群中的鼠李科植物时所见情况相同．显然，柔荑花序植物及木兰型植物在中侏罗世或更早的时代，已共生于中国北部，不能排除枫杨属，或连同胡桃科的其他属，曾于中生代之前起源于华北

Juglandaceous Plant ( Pterocarya ) from Middle Jurassic

A fossil fructification of Pterocarya associated in the Hai Fang Gou formation of Middle Jurassic floras found in Eastern Yanliao region of North China resembles closely that of the modern species Pterocarya stenoptera C.DC. and P.tonkinensis (Franch.) Dode in morphology, structure and habits. It implies that the genus Pterocarya varies little from Jurassic to the present and that it has experienced a long course of development before Jurassic, such cases are similar as that seen in the research of Jurassic Paliurus and Zizyphus reported in 1990 from the same fossil flora. It was obvious Amentiferous and Magnolian had been in association in North China during Middle Jurassic or earlier time. Thus, it could not be excluded that Pterocarya or even the genera of Juglandaceae as a whole may originate in North China previous to Mesozoic Era.