Abstract: Rhinocerotoid fossils are relatively abundant in Paleogene deposits in South China.Many previous studies have investigated Paleogene rhinocerotoids from Yunnan Province (Russell and Zhai,1987; Zong et al.,1996). Zhang(1981) briefly reported some fossils from Xiaoguangnan Village, Guangnan, Yunnan Province, within the Guangnan Basin. Recently,a new specimen comprising a fragmentary left mandible was recovered from the Paleogene of Xiaoguangnan. The new fossil is referable to the rhinocerotoid clade Eggysodontidae. Mainly based on its less molarized p3-p4, the new specimen is regarded as intermediate between the primitive Late Eocene taxon Proeggysodon and the derived Oligocene genera Eggysodon and Allacerops. Here we describe the new specimen and discuss the age of the Yanshan Formation.Terminology used to describe dental features follows Qiu and Wang (2007).

摘要： 记述了云南广南盆地古近纪砚山组紧齿犀科(Eggysodontidae)一新属种：杨氏广南犀Guangnanodon youngigen. et sp. nov., 标本为一破损的带p3-m3的左下颌骨。新属种的特征为下前臼齿的臼齿化程度低，p3-p4的下内脊弱，向内收缩呈尖叶状，p4和m2的下次脊略偏向内侧倾斜，m3的下跟座与m2的相近，接近V形，p4-m3外齿带在下原尖和下次尖基部消失。这些特征表明广南犀明显比晚始新世的Proeggysodon进步，而比渐新世的其他紧齿犀类原始，其时代很可能为晚始新世最晚期。新标本的发现结合以前报道过的哺乳动物化石材料表明，广南盆地砚山组包含了中始新世晚期至晚始新世晚期的沉积。