化石点位于东乡县东源乡牙沟一带，是巨犀动物群化石的代表性产地。该点岩石地层可划为早渐新世他拉组、晚渐新世椒子沟组、中中新世东乡组。化石产出层位为晚渐新世椒子沟组的褐黄色砂岩和砂砾岩中，牙沟地点的哺乳动物化石，共有 4 目 8 属，共 10 类：阿尔泰查干鼠 （Tsaganomys altaicus Matthew et Granger），巨翼齿兽(未定种)（Megalopterodonsp．），河套裂爪兽 （Schizotherium ordosium Hu），蹄齿犀科（未定属、种）（Hyracodontidae gen．et sp．indet．），高冠阿尔丁犀（新种）（Ardynia altidentata sp．nov．），阿尔丁犀（未定种）（Ardynia sp．），霍尔果斯准噶尔巨犀 （Dzungariotherium orgosense Chiu），牙沟副巨犀（新种）（Paraceratherium yagouense Qiu et a1），兰州巨獠犀 （Aprotodon lanzhouensis Qiu et Xie），巨颌副狶（相似种）（Paraentelodon cf．P．marognathus Qiu et a1．）。
The fossil site, situated in the area of Yagou, Dongyuan Township, Dongxiang County, is a representative place for the fossils of the giant rhinoceros fauna. The strata at this site can be divided into the Early Oligocene Tala Formation, the Late Oligocene Jiaozigou Formation and the Mid-Miocene Dongxiang Formation; the fossil-producing layer is the brown sandstone and sandy conglomerate in the late Oligocene Jiaozigou Formation. The mammalian fossils at the Yagou site have 4 orders, 8 genera, total 10 species: Tsaganomys altaicus Matthew et Granger, Megalopterodon sp., Schizotherium ordosium Hu, Hyracodontidae gen. et sp. indet．, Ardynia altidentata sp. nov., Ardynia sp., Dzungariotherium orgosense Chiu, Paraceratherium yagouenseQiu et a1., Aprotodon lanzhouensis Qiu et Xie, Paraentelodon cf. P. marognathus Qiu et a1..
