陕西蓝田灞河组陕西转角羚一新种(英文)

A NEW SPECIES OF SHAANXISPIRA(BOVIDAE, ARTIODACTYLA, MAMMALIA) FROM THE BAHE FORMATION, LANTIAN, CHINA

1997～ 2 0 0 1年 ,中科院古脊椎动物与古人类研究所与芬兰赫尔辛基大学合作 ,于灞河组地层中发现哺乳动物化石计 45种。其中牛科化石种类与蓬蒂期典型三趾马动物群中的种类不同 ,至少存在分别归属于Shaanxispira、Protoryx、Dorcadoryx和Gazella的 4个新的种类。本文仅记述其中陕西转角羚羊一新种 :灞河陕西转角羚 (Shaanxispirabaheensissp .nov .)。该种主要鉴定特征 :角心长而直 ,粗壮 ,横断面呈圆形 ,具一条发育的棱 ,起始于前内侧 ,右角上呈顺时针方向旋转一周至一周半 (从角基部视 ) ,角心前视向两侧中等程度散开 ,侧视中等后倾 ,起始于眼眶之后 ,角柄短。鼻骨窄 ,向上隆起 ,其后缘延伸至眼眶前棱之后的位置 ;眶前窝较宽浅 ,面部长而窄 ;角前额顶宽、稍隆起 ,眶上孔成椭圆形 ,眶上窝发育 ,向前的沟槽可延伸至泪骨 ;额骨在角前轻微隆起 ;角后颅顶宽、短 ,颅轴与面轴交角约为 90°。枕面宽、平 ,面向后下方。牙齿齿冠中等高度。臼齿上底柱与肋皆不发育。p4的下后尖位于下原尖之后 ,在老年个体上与下内尖连接 ,封闭后内谷。与已知大型转角羚羊相比较 ,灞河组新发现的种类与周氏陕西转角羚最为接近。不同的是该新种角心只发育一条棱 ,而不是两条 ,角心横断面呈圆形 ;顶骨较短 ;臼齿列相对较短 ,下臼?

A new species of large bovid Shaanxispira, S. baheensis is briefly described. The materials were found from the middle part of the Bahe Formation, Lantian County, China. S. baheensis is characterized by having straight horn cores with a clockwise twisted keel on the right, positioned behind the orbit. The braincase is rather short in respect to the width, and the cranial axis is at about 90° with the facial axis. The occipital surface is wide and flat with a wide mastoid exposure. No basal pillars on the labial side of lower and on the lingual side of upper molars. The phylogenetic relationships of the Shaanxispira with some other large bovids are also tentatively discussed. There possibly existed a group of large bovid of tribal or subfamilial level that died out during the late Miocene, which includes the Urmiatherium, Plesiaddax, Hezhengia, Shaanxispira, and possibly Sinotragus.