甘肃天水武山县南峪村的维曼嵌齿象及其生物地层学意义(英文)

Gomphotherium wimani from Wushan County, China, and its implications for the Miocene stratigraphy of the Tianshui area

报道了甘肃天水地区武山县四门镇南峪村地点发现的一件残破的未成年维曼嵌齿象(Gomphotherium wimani)下颌,标本保存有完整的p3,dp4,m1齿列。颊齿齿冠显示出嵌齿象属(Gomphotherium)的一些进步特征,例如齿脊前后压缩,齿谷宽阔,副齿柱后中心小尖凸显,中附锥和中心小尖趋于分裂,有弱的白垩质发育,符合维曼嵌齿象的鉴定特征。维曼嵌齿象此前发现于甘肃的中中新统,而南峪村地点的含化石地层可与周围其他地点的中中新统对比,因此,南峪村地点维曼嵌齿象层位的地质时代为中中新世。同时,结合孢粉学研究的结果,可能说明中中新世时期,天水地区气候温暖湿润,适宜低齿冠的哺乳类如嵌齿象等动物生存。

A fragmentary juvenile mandible referable to Gomphotherium wimani is described in this report. It was discovered at the Nanyucun Locality, Simen Township, Wushan County, Tianshui area, Gansu Province. Both the left and right p3, dp4, and ml are completely preserved in this specimen. The cheek teeth show characters that are derived within the genus Gomphotherium, such as anteroposterior compression of lophids associated with wide interlophids, presence of weak posttrite central conules, multiplication of mesoconelets and central conules, and weak cementation. These features are consistent with the diagnosis of G. wimani. G. wimani was originally discovered in the Middle Miocene of Gansu, and the fossiliferous horizon within the Nanyucun exposures that yielded G. wimani can be correlated with strata at neighboring Middle Miocene localities. Therefore, the G. wimani horizon at Nanyucun should be dated to the Middle Miocene. In combination with palynological data, the discovery of G. wimani at the Nanyucun Locality implies that the paleoenvironrnent of the Tianshui area in the Middle Miocene was probably relatively warm and humid, suitable for large populations ofbrachyodont mammals such as gomphotheres.