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云南腾冲新近系樟科润楠属两种化石及其古环境意义

ISSN号：1006-7493
期刊名称：高校地质学报
时间：0
页码：90-98
语言：中文
分类：P534[天文地球—古生物学与地层学;天文地球—地质学]
作者机构：[1]兰州大学资源环境学院,甘肃兰州730000, [2]南京地质古生物研究所现代古生物学与地层学国家重点实验室,江苏南京210008
相关基金：基金项目：国家自然科学基金（40772012）;“973”（2006CB701400）;现代古生物学与地层学国家重点实验室（中国科学院南京地质古生物研究所）基金（063101）资助.
相关项目：滇西腾冲—陇川新近纪植物化石角质层的古气候指示作用

关键词：润楠属化石, 角质层, 新近纪, 古环境, 云南, Machilus fossils, cuticle, Neogene, palaeoenvironment, Yunnan

中文摘要：

角质层微细构造特征是化石植物鉴定的重要依据，实验研究了云南腾冲新近系樟科润楠属薄叶润楠Machilus leptophylla和长梗润楠（近似种）Machilus cf．longipedicellata两个化石种的表皮微细构造特征，并与现存对应种类进行了表皮构造和叶结构特征的对比分析，补充证实了两化石种均属于自然分类属性。丰富了我国樟科润楠属化石记录。鉴于大气CO2浓度与植物叶片气孔指数呈负相关关系，Machilus叶片可以作为大气CO2浓度的生物指示器。研究表明，利用该类化石叶片气孔参数可推测地史时期古大气CO2浓度，揭示了新近纪滇西地区为温暖湿润性气候。

英文摘要：

A fossil leaf of Machilus leptophylla and a fossil leaf of Machilus cf. longipedicellata were collected from the Pliocene Mangbang Formation in Tengchong, Yunnan Province. Their architectural and epidermal characteristics were investigated by laboratory observation and cuticular analysis, and were compared with their living relative species. These two fossil leaves are oblong, coriaceous. Their primary veins are straight and moderately thick, and their secondary veins are pinnate. However, epidermal structure of the Lauraceae is very typical, the subsidiary cells are brachyparacytic and the guard cells are located under the two lateral subsidiary cells. The trichome bases of these two fossil leaves are unisetose. Therefore, the cuticles of two fossil leaves are considered to belong to the Machilus based on the detailed comparison of leaf architecture and epidermal structure. The results show that both leaf architectural and epidermal characteristics of the fossils are very similar to the living features and thus the combined usage of leaf architecture and cuticle in fossil classification and identification can yield more reliable results than solely used. The convincing identification has undoubtedly enriched the fossil records of Lauraceae in China. In addition, the stomatal density （SD） and the stomatal index （SI） have been calculated for these fossils and are compared with their living species. The results imply that leaves of fossil Machilus leptophylla and fossil Machilus cf. longipedicellata may have the potential to be used as indicators of palaeoatmospheric CO2 concentration. Through comparing the stomatal ratios of the modern Machilus leptophylla and Machilus longipedicellata （the living relative species of these two fossil leaves） to the fossil species, indicate that the CO2 concentration in the Pliocene is much higher than that of today. Our analysis suggests that the Neogene climate in western Yunnan might be warmer and more humid than the current condition.

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