• Platacanthomyid remains from the late Cenozoic deposits of East China

    分类: 地球科学 >> 地质学 提交时间: 2017-08-24 合作期刊: 《古脊椎动物学报》

    摘要: Remains of Platacanthomyidae from a late Cenozoic fissure in Fanchang, Anhui, and from the Miocene deposits of Sihong, Jiangsu, China are described. Three species and two genera, including two new species are recognized. They are Neocometes sinensis sp. nov. from Fanchang and Sihong, and N. magna sp. nov. and Typhlomys sp. from Fanchang. The Fanchang assemblage is a mixed sample with elements probably representing an interval spanning from the Early Miocene to the Pleistocene. Judging from fossil content and coloration in the sample, the two species of Neocometes are inferred to be Miocene in age, while the Typhlomys to be later. The joint occurrence of some typical Miocene elements in the assemblage seems to indicate that the Fanchang sample includes an association which can be closely correlated with the Early Miocene Sihong Fauna and the Shanwang Fauna of China, and with the Miocene faunas known from Thailand. Dental characters of Neocomets appear to suggest that the Asian species of the genus have undergone a rapid increase of size, heightening of dental crown, strengthening of ridges, and gradually development of ectoloph in the upper molars and endolophid in the lower molars, representing an evolutionary lineage different from that of Europe. 描述了安徽繁昌和江苏泗洪新发现的晚新生代堆积物中的刺山鼠科化石。化石共有两属3种,即产自安徽、江苏的中华新来鼠(新种) (Neocometes sinensis sp. nov.)和产自安徽的大新来鼠(新种) (N. magna sp. nov.)及猪尾鼠未定种(Typhlomys sp.)。安徽繁昌的材料来自裂隙堆积,采样时未作分层处理,对单个化石属种很难进行准确的时代确定;但根据所采集化石的组分和上下层位保存的颜色与埋葬方式上的差异,推测Neocometes的时代为中新世,而Typhlomys可能较晚。Neocometes属的出现和典型中新世动物成员的存在,表明繁昌这一含古猿的裂隙堆积中含有大致与江苏泗洪动物群和山东山旺动物群相当、甚至可与泰国中新世动物群对比的啮齿动物组合。新种牙齿的形态特征显示,Neocometes属在亚洲经历了个体迅速增大,齿冠增高,齿脊增强,上臼齿外脊和下臼齿内脊逐渐发育的过程,与该属在欧洲的演化趋势有所不同。

  • Several rarely recorded rodents from the Neogene of China

    分类: 地球科学 >> 地质学 提交时间: 2017-08-10 合作期刊: 《古脊椎动物学报》

    摘要:Numerous assemblages of fossil small mammals have been recovered from the Neogene deposits in China over the last 30 years or so. Nevertheless, some taxa in these faunas are represented by only a small number of isolated teeth from very few localities, and these are often assigned as indeterminate genus or species. Four peculiar taxa of rodents, Sayimys sihongensis, Apeomys asiaticus, Neocometes sp. from the Early Miocene Xiacaowan Formation of Sihong, Jiangsu Province, and Yuneomys pusillus from the Late Miocene Shihuiba Formation of Lufeng, Yunnan Province, are described in detail. Comparison of these specimens with similar materials from Eurasia or North America makes distinction from the known species of related genera possible, and therefore two new species (S. sihongensis, A. asiaticus) are named for the Sihong specimens, although the material is rare. A new eomyid genus Yuneomys, previously published under the name Leptodontomys pusillus, is based on specimens from Lufeng. A. asiaticus and Neocometes sp. represent the first records of the genera Apeomys and Neocometes known from Asia and China, respectively. The occurrence of the Neogene rodents in eastern China improves our knowledge of the spatial distribution of these poorly recorded animals, and contributes to a better understanding of paleobiogeographic relationships in Eurasia. Co-occurrence of the new genus with the bunodont eomyids Plesieomys and Heteroeomys in the Lufeng Fauna seems to indicate a differentiation of eomyid taxa in northern and southern faunas of China, and may reflect ecological partitioning within southeastern Asia during the Miocene. 30多年来,中国新近纪堆积物中发现了大量的小哺乳动物化石,但一些种类的材料很少,而且仅在个别地点出现,在动物群中常以未定属、种记述。详细描述了4种罕见的啮齿动物,其中3种,泗洪豪鼠(Sayimys sihongensis)、亚洲别齿始鼠(Apeomys asiaticus)和新来鼠(未定种) (Neocometes sp.)发现于江苏泗洪早中新世下草湾组,一种,细小云南始鼠(Yuneomys pusillus)产自云南禄丰晚中新世石灰坝组。与欧亚或北美有关材料的比较研究表明,江苏泗洪标本无法归入相关属的任何已知种,因此被确定了两个新种(S. sihongensis和A. asiaticus); 禄丰原归入Leptodontomys pusillus的标本与该属的特征不符,被指定为新属Ynueomys。泗洪的A. asiaticus和Neocometes sp.分别代表该属在亚洲和中国的首次记录;它们与S. sihongensis在亚洲远东地区的出现,增加了我们对这些稀有动物地理分布和欧亚古生物地理关系的知识。禄丰的新属Yuneomys与共生的Plesieomys和Heteroeomys属同为丘齿型始鼠类,可能都属热带或亚热带森林型动物;在禄丰动物群中缺少脊齿型始鼠类,与华北动物群的组成不同,似乎表明华南和华北始鼠动物群在中新世期间已有明显的分异,进而支持这一时期亚洲出现了不同生态区系的设想。

  • Discovery of Yuomys from Altun Shan, Xinjiang, China

    分类: 地球科学 >> 地质学 提交时间: 2017-08-02 合作期刊: 《古脊椎动物学报》

    摘要:Specimens reported in this note represent the frst discovery of Yuomys in Altun Shan. A new species, Yuomys altunensis, is established based on the following features: molars large and wide in proportion; metaconule distinctly separated from metacone, metaloph long, but incomplete; hypocone smaller than protocone; sinus extending to base of crown on lingual side; postcingulum connectting lingual side of metacone; metacone crescent and postcingulum short in M3. Yuomys altunensis is similar to Y. cavioides, Y. eleganes and Y. huangzhuangensis of late Middle Eocene in molar morphlogy. According to its evolutionary level, Y. altunensis is supposed as of late Middle Eocene in age, or slightly later. 记述了在新疆巴音郭楞蒙古族自治州若羌县阿尔金山地区彩虹沟首次发现的豫鼠一新种:阿尔金豫鼠(Yuomys altunensis sp. nov.)。其主要特征是臼齿的尺寸较大,比例上较宽,齿冠较高,臼齿的后小尖与后尖明显分开,后脊相对较长,但不完全,次尖明显小于原尖,舌侧内凹伸达臼齿齿冠基部,后齿带与后尖舌侧连; M3后尖为新月形,后齿带较短等。根据豫鼠臼齿的进化趋势和新种臼齿的尺寸较大、齿冠较高和舌侧内凹伸达齿冠基部的特征与Y. cavioides, Y. eleganes和Y. huangzhuangensis相近,但颊齿比例较宽判断 Y.altunensis可能与该3种处于同样的进化阶段或稍进步。其产出的地层时代很可能与它们相近或稍晚,即为晚中始新世或稍晚