分类: 地球科学 >> 地质学 提交时间: 2018-01-09 合作期刊: 《古脊椎动物学报》
摘要: An adult skull with articulated atlas and an adult mandible, collected by Emile Licent in 1920 from the Late Miocene of Qingyang (Gansu, China), is recognized as a new species Chilotherium licenti sp. nov. These specimens possess typical characters of the genus Chilotherium, such as the strongly expanded mandibular symphysis, the huge and dagger-shaped i2s with an upturned medial flange, strongly constricted protocones, well-developed crochet and crista, and weakly developed parastyle folds and paracone ribs. Chilotherium licenti is characterized by the near absence of lingual and buccal cingula, and the medifossette on P2 to M2 forming by well-developed crochet and crista. The derived characters of the new species indicate that it is the highly specialized taxon of the genus Chilotherium, corresponding to MN12-13 of the Turolian in Europe. Based on a phylogenetic analysis of rhinocerotids, C. licenti from the Late Miocene is the most derived species in the known species of the Chilotherium lineage.
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: 嵌齿象是真象的基干类群,其研究历来受到重视,同时也存在很多争议。维曼嵌齿象(Gomphotherium wimani)是中国的一个特有种,之前仅有一些牙齿和破碎下颌的报道,研究者对其形态特征和演化地位的认识一直比较模糊。本文报道了发现于甘肃省临夏盆地的维曼嵌齿象的新材料,包括上沟地点一件未成年头骨和倒黑沟地点属于同一个体的部分颊齿。通过研究对比,认为维曼嵌齿象是嵌齿象中一个比较进步的种,具有如下独有特征:颊齿的主齿柱前后中心小尖分裂并成嵴状,副齿柱趋向于分裂,发育有弱的副齿柱中心小尖,齿谷中等开阔,齿冠相对较高。对过去发现的维曼嵌齿象材料的厘定表明,该种最初建立时产于泉头沟地点的一颗m3实际上是葛氏铲齿象(Platybelodon grangeri)的M3; 而西宁吊沟地点发现的维曼嵌齿象的一件M3极有可能属于铲齿象类(amebelodontids)。对厘定后的维曼嵌齿象地点的研究表明,维曼嵌齿象分布于中国甘肃、青海的几个中中新统地点,其时代基本上可以与MN6−MN7/8早期相对比,时代跨度估计为15~13 Ma。
分类: 地球科学 >> 地质学 提交时间: 2017-08-08 合作期刊: 《古脊椎动物学报》
摘要: Mammut is the terminal taxon of the proboscidean group Mammutidae, which survived to the Late Pleistocene. Although this genus was widely distributed in the Pliocene of Eurasia and the Pleistocene of North America, little is known about its early evolution. Here, we report on Mammut cf. M. obliquelophus from the Upper Miocene of northern China based on new fossil material, including an almost complete juvenile cranium and other remains, which show many primitive features within Mammutidae and clearly demonstrate the morphological evolution of Mammut. The strongly laterally expanded lateral wing of the occiput and the presence of basal constriction of the incisive fossa display cranial similarity between Mammut cf. M. obliquelophus and both Eozygodon morotoensis and Choerolophodon guangheensis, early representatives of the Mammutidae and Choerolophodontidae, respectively, indicating the close relationship between these two groups: both of them are located at the basal phylogenetic positions in Elephantimorpha.This result is further confrmed by a cladistic analysis.