分类： 生物学 >> 生物进化论 提交时间： 2024-05-31
摘要： Within the dicynodont genus Turfanodon, there are two recognized species, T.bogdaensis and T. jiufengensis. Both species are known by relatively complete cranial materials, but the mandibles and most postcranial bones have been described only for T. jiufengensis. This paper reports new dicynodont specimens from Turpan, Xinjiang, referring them to T. bogdaensis. They can clearly be differentiated from T. jiufengensis by the flatter lateral surface of the snoutregion, a prominent swelling on the lateral dentary shelf, and the rounded femoral head. Thediagnosis of Turfanodon is revised. The combination of a flat circumorbital rim, posterior portionof anterior pterygoid rami with converging ventral ridges, and a possible autapomorphy, a deepnotch on scapula forming procoracoid foramen, are confirmed. It also differentiated from alldicynodonts other than Myosaurus, Kembawacela and Lystrosaurus by having accessory ridgeslateral to the median palatal ridge.
分类： 生物学 >> 生物进化论 提交时间： 2024-03-15
摘要： The previously alleged ‘eugnathid amiiform’ Sinoeugnathus kueichowensis is asmall-sized halecomorph from the Middle Triassic (Ladinian) marine deposits of Guizhou andYunnan, China. A morphological redescription and taxonomic revision of this taxon are providedbased on a detailed examination of 15 new specimens. Among them, IVPP V24315 (standardlength = 64 mm) is appointed as the neotype, given that the holotype is missing. Studies of thesespecimens revealed some morphological details previously undescribed or misidentified forthis taxon, including a hatchet-shaped antorbital, two broad suborbitals, a sensory canal in themaxilla, and three pairs of extrascapulars. For the first time, Sinoeugnathus was incorporatedinto an analysis of halecomorph phylogeny, and the results recover it as the sister taxon of theAnisian Subortichthys from Luoping, Yunnan, and both are grouped with two Ladinian generaAllolepidotus and Eoeugnathus from the Monte San Giorgio area into a monophyletic group(namely Subortichthyidae fam. nov. herein) at the base of Ionoscopiformes. This taxonomicreassessment of Subortichthys provides new insights into the phylogeny and paleogeographicevolution of Ionoscopiformes.
分类： 生物学 >> 动物学 提交时间： 2023-07-12 合作期刊: 《古脊椎动物学报》
摘要： The previously alleged eugnathid amiiform Sinoeugnathus kueichowensis is a small-sized halecomorph from the Middle Triassic (Ladinian) marine deposits of Guizhou and Yunnan, China. A morphological redescription and taxonomic revision of this taxon are provided based on a detailed examination of 15 new specimens. Among them, IVPP V24315 (standard length = 64 mm) is appointed as the neotype, given that the holotype is missing. Studies of these specimens revealed some morphological details previously undescribed or misidentified for this taxon, including a hatchet-shaped antorbital, two broad suborbitals, a sensory canal in the maxilla, and three pairs of extrascapulars. For the first time, Sinoeugnathus was incorporated into an analysis of halecomorph phylogeny, and the results recover it as the sister taxon of the Anisian Subortichthys from Luoping, Yunnan, and both are grouped with two Ladinian genera Allolepidotus and Eoeugnathus from the Monte San Giorgio area into a monophyletic group (namely Subortichthyidae fam. nov. herein) at the base of Ionoscopiformes. This taxonomic reassessment of Subortichthys provides new insights into the phylogeny and paleogeographic evolution of Ionoscopiformes.
分类： 生物学 >> 动物学 提交时间： 2020-08-02 合作期刊: 《古脊椎动物学报》
摘要： 新鳍鱼类是辐鳍鱼亚纲中最大的现生类群，中三叠世卢加诺鱼科则是新鳍鱼类干群中的一支，具有特化的头骨和特别高的侧腹鳞片。自1939年命名以来，卢加诺鱼科仅以瑞士东部和南部、意大利北部和西班牙东南部中三叠世海相地层安尼期/拉丁期界线附近发现的瓷鳞卢加诺鱼(Luganoia lepidosteoides)为唯一代表。根据贵州兴义中三叠世晚期(拉丁期)海相地层发现的一块较完整的精美鱼化石，命名了卢加诺鱼属一新种，祥瑞卢加诺鱼(Luganoia fortuna sp. nov.)。新种代表了卢加诺鱼科在亚洲的首次出现，表明此科的生物地理分布比之前认识的要大很多。基于新种与模式种的比较研究，修订了卢加诺鱼属的鉴定特征，揭示了该属过去一些未注意到的解剖学特征，例如存在一对眶前骨，缺少板片状的方颧骨，背鳍基部具有一狭长的裸露身体区域；臀鳍很小，与尾鳍的距离比与腹鳍更近；后匙骨缺失。此外，详细列举了中国新种与欧洲模式种的形态差异，研究结果为了解卢加诺鱼属的形态多样性提供了重要信息。
分类： 生物学 >> 动物学 提交时间： 2019-01-16 合作期刊: 《古脊椎动物学报》
摘要： Beipiaosaurus inexpectus, a key taxon for understanding the early evolution of therizinosaurians, has not been fully described since it was briefly reported on by Xu, Tang and Wang in 1999. Here we present a detailed description of the cranial anatomy of the holotype of this theropod dinosaur. B. inexpectus is unique in some of its cranial features such as the postorbital process of the frontal is large and its abrupt transition from the orbital rim, a long and sharp anterior process of the parietal, the elongate ventral ramus of the squamosal process of parietal, and external mandibular fenestra deep dorsoventrally and extremely posteriorly located. A number of plesiomorphic cranial features (such as relatively large dentary and less downturned degree of dentary symphysis) suggest that B. inexpectus is an early-branching Therizinosaurian, as proposed by previous studies. New information derived from our study is not only important for our understanding of the cranial anatomy of B. inexpectus but also significant to the study of the evolution of Therizinosauria.
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： Ionoscopiformes, sister to Amiiformes, are an extinct group of halecomorph fishes previously known mainly from the late Middle Triassic (Ladinian) and Late Jurassic of Europe and the Early Cretaceous of the New World. They have not been known in China until recently two ionoscopiforms (Robustichthys and Panxianichthys) were found from the early Middle Triassic (Anisian) of Yunnan and Guizhou, respectively. Here, a new ionoscopiform, Subortichthys triassicus gen. et sp. nov., is described on the basis of six well-preserved specimens from the early Middle Triassic (Pelsonian, Anisian, ~244 Ma) marine deposits exposed in Luoping, eastern Yunnan, China. The discovery documents the second ionoscopiform from the Luoping fossil beds and one of the oldest ionoscopiforms in the world, providing important information for understanding the origin and early diversification of this group. Subortichthys is an unambiguous halecomorph as it possesses two synapomorphies of this clade: a symplectic articulating with the lower jaw and a notched posterior margin of the maxilla. Within the phylogenetic framework of the Halecomorphi, results of the phylogenetic analysis place Subortichthys at the base of the Ionoscopiformes because it bears a sensory canal in the maxilla (an ionoscopiform synapomorphy), but lacks derived features of other ionoscopiforms. Notably, Subortichthys is distinguished from other members of this order with a unique combination of features, such as presence of three or four pairs of extrascapulars and a much expanded third infraorbital posteriorly contacting the preopercle. The new material reveals that the earliest diversification of ionoscopiforms was well undertaken in South China (a part of east Paleotethys Ocean then) by the early Middle Triassic (Anisian).
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