中文摘要：

在云南鹤庆上上新统三营组中发现大量壳斗科栎属高山栎组植物（Ouercussect．Heterobalanus）叶片化石．这些标本主脉呈“Z”字微弯，基部粗壮，至叶尖变细，二级脉羽状互生，且互相平行，在近叶缘1／3～1／2处分又；上表皮有单、多细胞毛基，无气孔，表皮细胞多为近四边形；下表皮只有单细胞毛基和环列型气孔器，表皮细胞为近四边形或五边形．这些特征虽然与毛脉高山栎（Q．rehderiana）、帽斗栎（Q．guyavifolia）及古帽斗栎（Q．preguyavifolia）等现生种和化石种比较相似，但仍与它们存在叶表皮毛密度和毛基类型的差异，故将其定为新种——鹤庆栎Quercusheqingensisn．sp．）．将鹤庆栎的气孔指数应用于已建立的其现存最近亲缘类群（NearestLivingRelatives，NLRs）——帽斗栎的气孔指数与大气pCO2的关系式，定量重建出晚上新世时期的古大气CO2浓度分别为263．42±24．86ppm（沿海拔梯度采集样品重建结果）和234．25±22．49ppm（历史标本样品重建结果），与前人结果相比基本一致，经过海拔校正后则十分吻合．同时进一步证明了晚上新世时期的古大气C02浓度低于现代水平，为利用现存最近亲缘类群作为代理（proxies）重建古大气CO2浓度提供了可靠的证据．

英文摘要：

Many leaf fossils belonging to Quercus sect. Heterobalanus were collected from the Upper Pliocene Sanying Formation in Heqing County, Yunnan Province, China. Leaves are oblong, elliptic or obovate with entire margin or spinous serrations, 3.1-8.7 cm in length and 1.8-5.7 cm in width. Leaf apex is round, mucronate or blunt round, while leaf base is heart-shaped, slightly heart-shaped or blunt round, and occasionally asymmetric. The petiole is slightly sturdy, straight or a bit curved, with 1.8-4.9 mm in length. The main vein of these specimens is slightly zigzagging, with a sturdy base attenuating to the apex. Secondary veins are pinnate, 7-12 pairs, alternate and parallel with the stretching angles from 40° to 73°, bifurcating near 1/3 to 1/2 of the leaf margin. Tertiary veins are, relatively thin, 5-7 bands in 1 cm2, and perpendicular to secondary veins. Quaternary, blind and marginal veins are not clear. The upper epidermis has both unicellular and multicellular trichomes without stomata, and most of the epidermal cells are nearly quadrangular. The lower epidermis has only unicellular trichomes and cyclocytic stomatal apparatuses, and the epidermal cells are nearly quadrangular or pentagonal. The stomatal apparatuses are 20-33 μm in length, 17-27 μm in width, with 2-6 μm wide in apertures. They spread casually with the stomatal density of 503±98 mm2 and the stomatal index of 8.90%±0.32%. The guard cells show kidney-shaped, with 5-7 subsidiary cells. These features are similar to Q. rehderiana, Q. guyavifolia, Q. preguyavifolia and some other extant or fossil species of Q. sect. Heterobalanus, but they are different in terms of density and type of trichomes. Both Q. guyavifolia and Q. preguyavifolia have more trichomes in total, and multicellular trichomes in lower epidermis which spread in veins and between veins. The fossil leaves of Q. sect. Heterobalanus in Heqing and Q. rehderiana have less trichomes, and the former has no multicellular trichome in lower epidermis, while the latter＇s multicellular