中文摘要：

描述广西渐新统宁明组近来发现的臭椿属（Ailanthus Desf．）翅果化石。通过对臭椿属翅果腹脉和花柱痕的位置以及翅果大小3个性状的比较形态学研究，广西宁明组的翅果化石被归入2个种，即古臭椿（Alconfucii Unger）和塔德臭椿（A．tardensisHably）。古臭椿过去广泛发现于欧亚和北美始新世以来的中纬度地区，其翅果腹脉位于边缘或边缘稍内、花柱痕与种子中部处于同一水平、长20-42mm，而广西宁明产的该化石种大多长40—53mm。塔德臭椿最早发现于匈牙利布达佩斯的下渐新统，其翅果腹脉位于边缘以内、花柱痕与种子顶部处于同一水平、长35—41mm，广西宁明则是该化石种的第2个产地。此外，过去还从斯洛文尼亚索卡（Socka）下渐新统报道了另外1个臭椿属翅果化石种巨臭椿（AgigasUnger）（长达57mm），它与古臭椿唯一可以区别的性状是翅果长度。基于广西宁明和其它产地的古臭椿翅果化石形态特征的连续性，巨臭椿被处理为古臭椿的分类学异名。本文研究的2个臭椿属化石种是迄今纬度最低的该属化石报道。结合臭椿属现生种的地理分布、系统发育关系以及相关化石种的地理和地层分布，探讨该属的生物地理起源与演化历史。

英文摘要：

AiZanthus Desf. （Simaroubaceae）, containing six extant species of deciduous and evergreen trees or small trees, is currently distributed from East, South and Southeast Asia to North Oceania. Its fossils are widely recorded from the early Eocene to Pleistocene in the middle latitudes of the Northern Hemisphere. This article describes two fossil species of AiZanthus winged fruits from the Oligocene Ningming Formation of Guangxi Zhuang Autonomous Region, China. They represent the southernmost fossil record of the genus. The studied fossil fruits are attributed to two fossil spe- cies, Ailanthus confucii Unger and A. tardensis Hably on the basis of morphological comparison. AiZanthus confucii has been widely found in the middle latitudes of Eurasia and North America from the early Eocene and it is distinguished by a ventral vein that is marginal or only slightly intramarginal, a stylar scar nearly at the same level as the middle of the seed and the fruits range from 20 mm to 42 mm in length. Fruits of A. confucii from Oligocene Ningming Formation of Guangxi commonly range from 40 mm to 53 mm in length. Ailanthus tardensis was erected from the Early Oligocene of Budapest, Hungary and we consider that it is characterized by the intramarginal ventral vein, scar of style nearly at the same level as the apex of the seed and the fruits 35--41 mm. Ningruing is the second locality of A. tardensis. Ailanthus gigas Unger, is distinguished from A. confucii by the winged fruit length （up to 57 mm） alone and is known from one single locality. Because of the character continuity in fossil fruits from Guang- xi and other localities, A. gigas is reduced as a taxonomic synonym of A. confucii. Based on the geographic distribution and phylogeny of modern Ailanthus as well as its fossil occurrences, we suggest that this genus may have originated in North Pacific-Rim areas of the North Hemisphere by the early Eocene, migrated southward and became extinctions in Europe and North America since the late Miocene onwards, and formed t