分类： 生物学 >> 动物学 提交时间： 2022-06-07 合作期刊: 《古脊椎动物学报》
摘要： Nothosaurus luopingensis n. sp. from Member II of the Guanling Formation (Anisian, Middle Triassic) of Luoping, Yunnan, China is described based on a specimen comprising the skull and most of the postcranial skeleton. The specimen is assigned to Nothosaurus of Eosauropterygia as suggested by a series of skull characters, such as the maxillary tooth row extending posteriorly beyond the level of the anterior margin of the upper temporal fenestra, the longitudinal diameter of the upper temporal fenestra is more than twice as long as that of the orbit, and the presence of maxillary fangs. Compared with Lariosaurus, the following morphological features of the pectoral girdle and the limbs also support the assignment of the specimen to Nothosaurus, i.e., the clavicles with expanded anterolateral corners, the characteristically curved humerus with a straight preaxial angle and a postaxial concavity, the distinct deltopectoral crest on the proximal part of the humerus, no hyperphalangy in the manus, and the absence of pachyostosis in the vertebrae and ribs. On the other hand, the specimen possesses some postcranial features that were previously considered to occur mainly in Lariosaurus, such as there being more than three ossifications in the carpus, having four sacral ribs, and an interclavicle without any trace of a posterior stem. These postcranial characters may no longer be used as the diagnostic features of Lariosaurus. N. luopingensis is distinguished from other Nothosaurus species by a unique combination of derived characters, including that the jugal enters the orbit, the nasals are separated, the posterior end of the frontal is bifurcate, pedal digits V and IV are long and subequal in length, and the ungula phalanx is stout. Our phylogenetic analysis reconfirms the monophyly of Nothosaurus and suggest that N. luopingensis is the sister group of N. yangjuanensis within the genus.
分类： 生物学 >> 动物学 提交时间： 2017-11-07 合作期刊: 《古脊椎动物学报》
摘要： Dianmeisaurus gracilis is restudied on the basis of a new specimen. It provides some new information, especially that on the skull roof, to the species. The most striking of those new characters include the snout (preorbital region) shorter than the orbit, the interorbital septum extremely narrow, the frontal with a sharp process at both ends, and the posterior margin of the skull roof deeply V-shaped. A phylogenetic analysis with new information confirms that Dianmeisaurus is the sister group of Diandongosaurus and that these two genera, together with those Chinese taxa (Majiashanosaurus, Dianopachysaurus, Keichousaurus, and Dawazisaurus), form a monophyletic clade which is more closely related to the Nothosauroidea than to a clade formed by the European pachypleurosaurs.
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： Tetrapod assemblages provide a useful means for global correlation of the terrestrial Triassic sedimentary deposits, but currently no reliable temporal framework has been achieved for the Middle Triassic tetrapod assemblages. Here we report U-Pb zircon chemical abrasion–thermal ionization mass spectrometry dates for five volcanic ashes interbedded with vertebrate fossils from the Ermaying and Tongchuan formations of China. Our results support a late Anisian age for the Sinokannemeyeria Fauna and an early Ladinian age for Yonghesuchus Fauna. It is now possible, through biostratigraphic correlation, to provide accurate ages to other Middle Triassic successions such as the Upper Cynognathus Assemblage Zone of the Karoo of South Africa, the Eryosuchus fauna of the Donguz Suite of Russia and the Karamayi Formation of Xinjiang, China. The base of Anisian (Lower/Middle Triassic boundary) should lie below the base of the Ermaying Formation in the Ordos Basin. 四足动物组合带是全球陆相三叠系对比的有力手段，但是迄今为止中三叠世的四足动物组合尚没有可靠的时间框架。本文报道了五个采自二马营组和铜川组，与四足动物化石共同产出的火山凝灰岩样品的锆石化学剥蚀-热电离质谱法年龄。结果表明中国肯氏兽动物群时代为安尼期晚期，而永和鳄的时代为拉丁期早期。通过生物地层对比，这一结果还为其他中三叠世的四足动物组合，如南非的犬颌兽带上部、俄罗斯的引鳄动物群以及新疆的克拉玛依组提供了准确的年龄。鄂尔多斯盆地下中三叠统界线应低于二马营组底界。
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： Dianmeisaurus gracilis is restudied on the basis of a new specimen. It provides some new information, especially that on the skull roof, to the species. The most striking of those new characters include the snout (preorbital region) shorter than the orbit, the interorbital septum extremely narrow, the frontal with a sharp process at both ends, and the posterior margin of the skull roof deeply V-shaped. A phylogenetic analysis with new information confirms that Dianmeisaurus is the sister group of Diandongosaurus and that these two genera, together with those Chinese taxa (Majiashanosaurus, Dianopachysaurus, Keichousaurus, and Dawazisaurus), form a monophyletic clade which is more closely related to the Nothosauroidea than to a clade formed by the European pachypleurosaurs. 根据一件产自云南罗平中三叠世关岭组II段的新标本并结合产自相同地点和地层中的模式标本对纤细滇美龙(Dianmeisaurus gracilis Shang & Li, 2015)进行了详细研究。原模式标本暴露其腹面，而新标本暴露其背面，两者互相补充提供了更完整、精确的纤细滇美龙解剖学信息。新材料揭示该种具有非常短小的吻部，眶前区的长度不仅短于眶后区长度，甚至短于眼眶的长度；外鼻孔小且位置靠前，即鼻孔前区的长度短于鼻孔后缘与眼眶前缘之间的距离；由两额骨构成的眼眶间隔非常狭窄，宽度小于顶骨平台宽度的1/3;额骨前后两端均具渐尖的突起；顶骨后部不收缩，顶骨平台后缘呈深V型。补充了新信息和包含更多属种(如Dawazisaurus)后的系统发育学分析支持了之前滇美龙和滇东龙互为姊妹群的结论，同时它们和马家山龙、滇肿龙、贵州龙和大洼子龙一起构成了一个仅由中国的属种组成的单系类群。与欧洲肿肋龙类群(Dactylosaurus, Anarosaurus, Serpianosaurus和Neusticosaurus)相比，这一单系类群与幻龙类有更近的亲缘关系。
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