中国贵州中生代四足类足迹化石的回顾与新发现

贵州省拥有丰富的中生代脊椎动物化石记录,多为三叠纪海生爬行类化石,侏罗纪和白垩纪的脊椎动物化石较少。目前,贵州省已发现中生代爬行类足迹点9处,分别为贞丰牛场、贞丰龙场、安顺幺铺、赫章辅处、毕节响水(2处)、仁怀茅台、赤水宝源和习水同民足迹点。文中除描述了贞丰龙场新增的一批足迹化石外,整理并总结了所有足迹点的发现史、研究现状、足迹类型与特征以及所反映的古生态信息。已发现的遗迹记录由69条行迹和420个孤立足迹组成,足迹总数达991个。所有的遗迹化石指示了至少477个造迹者,包括海生爬行类、手兽足迹类、非鸟兽脚类、鸟类、蜥脚类和鸟臀类等,其中三叠纪以海生爬行类主导,侏罗纪和白垩纪以蜥臀类主导。这个数据集为贵州中生代古生物类群的多样性提供了重要的信息,是晚中生代稀缺骨骼化石记录的良好补充,为研究贵州省中生代脊椎动物群的古生态与古环境提供了更多的证据。     

中三叠世安尼期罗平生物群海生爬行类研究新进展

2007年,中国地质调查局成都地质调查中心云南1∶5万区域地质调查项目组在距罗平县城东南15 km的罗雄镇大洼子村附近中三叠统关岭组二段地层中发现了罗平生物群。罗平生物群目前已经发现有海生爬行类、鱼类、节肢动物、棘皮动物、菊石、双壳、腹足类、腕足类、植物等十多个大类的化石,完好地体现了当时海洋生物的多样性,是目前已知化石分异度最高的三叠纪海生化石库之一。根据含化石地层中发现的微体化石牙形石Nicoraella Kockeli带,确认罗平生物群时代为中三叠世安尼期Pelsonian亚期。罗平生物群目前发现的海生爬行类种类丰富,基本涵盖了三叠纪时期主要的海生爬行类别,包括鱼龙类、鳍龙类、原龙类以及初龙类。中生代是对海生爬行类至关重要的时期。由于一直没有发现它们留下的遗迹化石,它们的运动模式还一直存在争议。云南罗平生物群海生爬行类研究中发现数百枚保存完好的幻龙类足迹——罗平双桨迹Dikoposichnus luopingensis,为研究其运动模式提供了直接的证据。另外罗平生物群中巨型捕食者张氏幻龙Nothosaurus zhangi的发现也支持了罗平双桨迹造迹者的存在。张氏幻龙拥有三叠纪世界上最大的头骨,这些处于食物链顶层的海生爬行类的繁盛说明当时生态系统已经很完善,代表了二叠纪末生物大灭绝之后海洋生态系统的全面复苏。     

罗平生物群的发现与研究进展——据云南1:5万罗平县等四幅区调和专题调查成果

成都地质调查中心云南区调项目组2007年在罗平县中三叠统关岭组二段中发现了罗平生物群。罗平生物群是三叠纪的化石宝库,化石包含了脊椎动物和无脊椎动物。脊椎动物以海生爬行类和鱼类为主。无脊椎动物以节肢动物为主,伴生有双壳类、腹足类、菊石、棘皮动物、腕足类、牙形石、有孔虫和植物类化石。牙形石研究显示罗平生物群处于Nicoraella kockeli牙形石带,时代上属于中三叠世安尼期Pelsonian亚期。罗平生物群保存在一个局限的台盆环境中。其化石的特异保存很可能与底层水缺氧和微生物席的密封作用有关。罗平生物群目前是研究三叠纪海洋生态系统复苏的最好的一扇窗口,也是三叠纪海生鱼类和节肢动物化石保存最好的产地之一,为研究二叠纪末大绝灭后海洋生态系统复苏以及中生代海洋生态系统的演化历史提供了新材料。     

海生四足类的集群绝灭

中生代海生爬行类分类已超过6个目中的30个科,例如包括鱼龙类、蛇颈龙类、海生湾鳄类(众所周知从三叠纪到白垩纪)、沧龙类(晚白垩世)及海龟鳖类(晚白垩世)。就海生爬行类而论,集群绝灭是在晚三叠世,并且很清楚地确认,在晚白垩世至少还有一个科,而在那里晚侏罗世的一个科没有得到公认。植龙类、盾齿龙类、幻龙类及其它一些种     

中国的三叠纪恐龙足迹化石

中国是世界上恐龙足迹化石最丰富的国家之一,中国发现的恐龙足迹化石绝大多数属于侏罗纪和白垩纪的,三叠纪恐龙足迹非常少见。目前在四川彭县、天全和富顺发现的晚三叠世恐龙足迹化石是中国发现的时代最早的恐龙足迹化石。由于中国还未发现三叠纪恐龙骨骼化石,因此这些恐龙足迹化石填补了中国恐龙研究的一段空白。目前发现的三叠纪恐龙足迹化石数量较少、特征不很明显、分类位置也不是很明确,因此今后还需要进一步加强四川盆地晚三叠世恐龙足迹化石的调查和深入研究。     

中国的三叠纪恐龙足迹化石

中国是世界上恐龙足迹化石最丰富的国家之一,中国发现的恐龙足迹化石绝大多数属于侏罗纪和白垩纪的,三叠纪恐龙足迹非常少见。目前在四川彭县、天全和富顺发现的晚三叠世恐龙足迹化石是中国发现的时代最早的恐龙足迹化石。由于中国还未发现三叠纪恐龙骨骼化石,因此这些恐龙足迹化石填补了中国恐龙研究的一段空白。目前发现的三叠纪恐龙足迹化石数量较少、特征不很明显、分类位置也不是很明确,因此今后还需要进一步加强四川盆地晚三叠世恐龙足迹化石的调查和深入研究。     

遗迹化石对显生宙5大生物-环境事件的响应

通过系统梳理与奥陶纪-志留纪、晚泥盆世弗拉期-法门期、二叠纪-三叠纪、三叠纪-侏罗纪、白垩纪-古近纪之交 的5次生物大灭绝期遗迹化石记录相关的生物和环境事件,发现遗迹化石对5次大灭绝事件为负响应,即在大灭绝事件之后 的残存期和复苏期期间,遗迹化石的多样性、丰度、潜穴直径、生物扰动强度、遗迹组构阶层都大为减小.遗迹化石反映的造迹 生物行为习性和觅食策略在5次生物大灭绝事件后也各有不同,食沉积物性觅食策略在晚奥陶世和晚白垩世大灭绝事件之 后占据主导,滤食性觅食策略在晚三叠世大灭绝事件之后占据主导,机会主义遗迹(如Planolites)、食沉积物性和滤食性等多 种觅食策略和行为习性在晚泥盆世F-F和晚二叠世两次大灭绝事件之后占据主导.晚泥盆世F-F和晚二叠世两次大灭绝事件 之后,遗迹化石记录了底栖生物系统由简单向复杂、由二维向三维生态空间拓展的变化趋势.      

贵州盘县生物群时代的牙形石地层证据

最近在贵州省盘县—普安地区中三叠统关岭组顶部地层中发现了大量保存完整、精美、属种丰富的海生爬行类化石,包括鱼龙类、幻龙类、原龙类等主要海生爬行类群。这些珍稀海生爬行类化石的发现对探讨海生爬行类早期起源、演化、古生物地理迁徙研究具有重要意义。为确定其产出层位的精确地质年代,本文选择贵州盘县新民羊圈—楚皮凹剖面关岭组顶部地层进行了系统的牙形石样品采集、分析。结果表明,自下而上可识别出4个牙形石生物带,即Nicoraellagermanica带,Nicoraella kockeli带,Paragondolella bif urcata带和Neogondolella constricta带,可…     

贵州贞丰中三叠统关岭组中Chirotherium--原始爬行类足迹研究

在贵州省贞丰县龙场镇和牛场镇两地中三叠统关岭组下段的泥质白云岩中保存有古老的爬行类--"手兽"的足迹化石--Chirotherium.该足迹为四足动物留下的行走轨迹,后足保存较完整,前足可见零星和不完整的趾痕.单个足迹由五个脚趾和后掌组成,由于其中的四个脚趾伸向前方而第五趾由后掌外侧横向伸出且向后弯曲,整个足迹看上去犹如人的手掌印痕.由前足脚印保存不完全可以判断,该造迹动物既可以四足行走又可以仅靠后足奔跑.龙场足迹点保存完整的后足脚印最大为长16cm,宽14cm,平均单步长70.2em,复步长为140cm;而牛场足迹点所见最大后足脚印长达25cm,宽17cm,平均单步长为52cm,复步长为98.5cm.笔者等参照国际上流行的计算方法,根据脚印长度和步长大小计算了两地造迹动物的臀高和行走速度:臀高大约0.64～1.0 m,估计身长可达2～3m,行走速度4～10km/h.考虑到造迹动物当时仅仅处于漫步和小跑状态,推测其奔跑速度可以达到20km/h以上.于欧洲、美洲等地发现的Chirotherium多数保存于三叠纪的红色砂泥岩层表面,其中多数岩层发育泥裂构造;还有些则保存于薄层碳酸盐岩层的表面,也多数发育泥裂构造.贞丰的两处足迹都保存于中三叠统关岭组下段发育泥裂构造的泥质白云岩表面,同样反映了当时炎热干旱的气候特点.在欧洲、南美洲、北美洲和亚洲的中国都发现了仅存于三叠纪的Chirotherium,说明这些地点在当时曾经属于同一个大陆,而且都处于干旱、炎热的低纬地区.由于该足迹点当时处于扬子古大陆南缘的台地上,而其东南侧则是著名的三叠纪南盘江复理石盆地,对该足迹的进一步研究有利于探讨台地和盆地的相变关系和生态差异,进而揭示盆地演化过程中与扬子板块的相互作用.     

中国中生代木化石研究新进展:多样性变化及古气候波动

作为植物化石的重要组成部分,木化石不仅在探究地质历史时期植物群的组成特征和植物界演化方面发挥着重要作用,而且也是反映陆地生态系统古气候变化和古生态环境重建的重要证据之一。中国中生代木化石不仅数量丰富,而且类型多样,研究成果丰硕。近年来,在四川、重庆、云南、辽西和新疆等三叠纪—白垩纪化石产地和层位陆续发现了一批木化石新材料,进一步丰富了我们对中国中生代木化石的多样性的认识,并在利用木化石揭示三叠纪至白垩纪陆相古气候特征和变化方面取得积极进展。文中重点介绍在四川盆地晚三叠世、辽西侏罗纪燕辽生物群及早白垩世热河生物群中的木化石新发现并分析其古气候指示意义,揭示上述化石所反映的气候降温事件、古气候波动及其与带毛恐龙出现的关系等。通过对中生代木化石多样性演化、时空分布模式以及木材生长轮解剖特征的研究和分析揭示侏罗纪和白垩纪的古气候整体特征,并对中国中生代木化石研究领域存在的问题和未来的研究方向提出展望。     

Biostratigraphy of Triassic Marine Reptiles in Southwest Guizhou and Its Adjacent Area

This paper briefly reviews the Triassic marine reptile fossils in Guizhou Province, especially the fossils that have been recently found in the Guanling area. Based on three sections at Guanling and Xingyi, Guizhou Province and Luoping, Yunnan Province, four horizons with vertebrate fossils are recognized in the Middle and Upper Triassic of this area; They are from bottom to top: Member I and Member II of the Guanling Formation, and the Zhuganpo Member and the Wayao Member of the Falang Formation.     

A Review of the Tetrapod Track Record in China,with Special Reference to Type Ichnospecies:Implications for Ichnotaxonomy and Paleobiology

<正>"Splitting" and "lumping" are perpetual problems in vertebrate,especially dinosaur, ichnotaxonomy.Chinese dinosaur ichnotaxonomy,which began in 1940,provides a series of interesting case studies,highlighting the dual problems of historical and dubious ichnotaxonomy. Chinese Mesozoic tetrapod track types have been placed into 63 ichnospecies(one Triassic,28 Jurassic,and 34 Cretaceous),exclusive of other,non-type ichnospecies or ichnotaxa identified from China.Fifty-two(～83%) of these 63 tetrapod ichnospecies were placed in monospecific ichnogenera. At the ichnogenus level,we prune—either by recognizing nomina dubia or by synonymy—17 from the list of 53 dinosaurian ichnogenera(a 32%reduction),leaving 36 ichnotaxa that we consider valid. Most of the cuts affect Jurassic theropod ichnotaxa,which are reduced from 23 to only nine because most ichnogenera are subjective junior synonyms of Grallator and Eubrontes.Fewer Chinese Cretaceous ichnotaxa(only six of 21 ichnogenera) are obvious nomina dubia or subjective synonyms, suggesting greater east Asian endemism during this time.Because ichnospecies differences are subtle, we provisionally retain ichnospecies as valid pending detailed comparative analyses of congeneric ichnospecies.This synthesis is long overdue and is necessary to address problems of historical and provincial ichnotaxonomy,which severely hamper comparisons of tetrapod ichnofaunas in space and time.     

150 Million year history of North China Craton disruption preserved in Mesozoic sediments of the Ordos basin

ABSTRACT

The Ordos Basin, situated in the western part of the North China Craton, preserves the 150-million-year history of North China Craton disruption. Those sedimentary sources from Late Triassic to early Middle Jurassic are controlled by the southern Qinling orogenic belt and northern Yinshan orogenic belt. The Middle and Late Jurassic deposits are received from south, north, east, and west of the Ordos Basin. The Cretaceous deposits are composed of aeolian deposits, probably derived from the plateau to the east. The Ordos Basin records four stages of volcanism in the Mesozoic–Late Triassic (230–220 Ma), Early Jurassic (176 Ma), Middle Jurassic (161 Ma), and Early Cretaceous (132 Ma). Late Triassic and Early Jurassic tuff develop in the southern part of the Ordos Basin, Middle Jurassic in the northeastern part, while Early Cretaceous volcanic rocks have a banding distribution along the eastern part. Mesozoic tectonic evolution can be divided into five stages according to sedimentary and volcanic records: Late Triassic extension in a N–S direction (230–220 Ma), Late Triassic compression in a N–S direction (220–210 Ma), Late Triassic–Early Jurassic–Middle Jurassic extension in a N–S direction (210–168 Ma), Late Jurassic–Early Cretaceous compression in both N–S and E–W directions (168–136 Ma), and Early Cretaceous extension in a NE–SW direction (136–132 Ma).     

Guanling Biota: A Marker of Triassic Biotic Recovery from the end-Permian Extinction in the Ancient Guizhou Sea

After a slow recovery from the end-Permian extinction during the Early Triassic and rapid radiation in the Middle Triassic, evolution of organisms reached a new peak phase in the Late Triassic. The Guanling Biota from the Wayao Member （conodont Paragondolella polygnathiformis Zone）, Falang Formation, Xinpu, Guanling County, Guizhou Province, southwestern China corresponds to this peak that marks the full recovery from the end-Permian extinction of marine ecosystems. The biota is of high diversity, containing well preserved and completely articulated skeletons of vertebrates comprising marine reptiles, fishes, and invertebrates including crinoids, ammonites, bivalves, and other fossils, and is one of the best examples of marine ecosystem records in life history. The fossil marine reptiles and crinoids are most significant in this biota, especially the marine reptiles, which provide an important link between the Triassic Pacific and Tethys, and between Triassic basal forms and the Jurassic-Cretaceous marine top predators. The most remarkable fossils are the large completely articulated ichthyosaur skeletons up to and more than 10 m, and the first recorded thalattosaurs and placodonts in China. Following our review, of the 17 named reptilian taxa the eight listed here are considered to be valid： three ichthyosaurs （Qianichthyosaurus zhoui Li, 1999; Guizhouichthyosaurus tangae Cao and Luo in Yin et al., 2000, Guanlingsaurus liangae Yin in Yin et al., 2000）, three thalattosaurs （Anshunsaurus huangguoshuensis Liu, 1999, Xinpusaurus suni Yin in Yin et al., 2000, Xinpusaurus kohi Jiang et al., 2004）, and two placodonts （Sinocyamodus xinpuensis Li, 2000, Psephochelys polyosteoderma Li and Rieppel, 2002）. Mixosaurus guanlingensis Cao in Yin et al., 2000 might be a junior synonym of Qianichthyosaurus zhoui Li, 1999, and Cymbospondylus asiaticus Li and You, 2002 and Panjiangsaurus epicharis Chen and Cheng, 2003 might be junior synonyms of Guizhouichthyosaurus tangae Cao and Luo in Yin et al., 2000. It needs to re-describe the holotypes after a complete preparation for clarifying the taxonomic status of Typicusichthyosaurus tsaihuae Yu in Yin et al., 2000, Xinpusaurus bamaolinensis Cheng, 2003, Neosinosaurus hoangi （Zhou in Yin et al., 2000）, Wayaosaurus geei Zhou in Yin et al., 2000, Wayaosaurus bellus Zhou in Yin et al., 2000 and Placochelys ？ minutus Yin and Luo in Yin et al., 2000.     

Mesozoic marine reptiles from Spitsbergen and their ecosystems

In the Mesozoic seas, the apex predators were reptiles. From the Arctic archipelago of Svalbard, the Spitsbergen Mesozoic Research Group has excavated numerous well preserved marine reptile skeletons in order to understand the biology of these animals and the environment they lived in. The work of eleven field seasons has made this one of the largest and most productive palaeontological research projects in the high Arctic world‐wide. The initial eight seasons focused on one of the richest occurrences of Late Jurassic—earliest Cretaceous (c. 150–139 Ma) marine reptiles in the world, and nearly sixty specimens have been collected, together with a diverse assemblage of invertebrates, some of which are associated with methane seeps. The last three seasons were spent investigating events further back in time, as Spitsbergen preserves the remains from some of the first marine reptile radiations in the wake of the most devastating extinction in the history of the Earth, at the Permian–Triassic boundary (c. 252 Ma).     

New marine reptile fossils from the Late Jurassic of Poland with implications for vertebrate faunas palaeobiogeography

A new marine vertebrate assemblage from the Late Jurassic (late Kimmeridgian) at Krzy?anowice near I??a in the NE margin of the Holy Cross Mountains in Poland is described. This new locality is rich in fossils of coastal and pelagic reptiles. The most frequent fossils are plesiochelyid turtle shell fragments and pliosaurid skull bones and teeth. The Krzy?anowice vertebrate assemblage is similar to the Late Jurassic Boreal/Sub-Boreal localities of the Kimmeridge Clay in Great Britain and Svalbard Archipelago in the Arctic, in the presence of pliosaurids and long-necked plesiosaurids. However, plesiochelyid turtles and crocodylomorphs are similar to those from the Mediterranean/Sub-Mediterranean sites of the northern border of the Tethys Ocean, as, for example, in the Swiss Jura Mountains and Southern Germany. This unique composition of the Krzy?anowice vertebrate fauna demonstrates that, during the Late Jurassic this new locality was located in the transitional palaeobiogeographic line referred to in this paper as the “Matyja-Wierzbowski Line”. The new palaeobiogeographical reconstructions of Late Jurassic of Europe are based on the composition of the Krzy?anowice locality and other sites with similar turtle-pliosaurid faunas which formed a long-term, stable ecological sympatry in marine ecosystems of the European Archipelago.     

Mesozoic exhumation history of the Grenvillian Oaxacan Complex,southern Mexico

We present the first fission‐track results from the Grenvillian Oaxacan Complex, southern Mexico. Time–temperature modelling of the data indicates that two significant Mesozoic cooling episodes are recorded in the Oaxacan Complex and these are interpreted as resulting from exhumation. The older cooling event took place from the Late Triassic to Middle Jurassic and is possible linked to the break‐up of Pangea (including the initial opening of the Gulf of Mexico during the Jurassic). The younger exhumation period in the Early Cretaceous is contemporaneous with the final stages of rifting of the Gulf of Mexico. Key stratigraphic records also provide independent evidence for these exhumation episodes. In our view, both Mesozoic rapid exhumation events were controlled by the activity of the Caltepec Fault Zone and the Oaxaca Fault. Our data suggest that both these large fault systems have remained active since, at least, the Late Triassic.     

Theropod assemblages and a new ichnotaxon Gigandipus chiappei ichnosp. nov. from the Jiaguan Formation,Lower Cretaceous of Guizhou Province,China

A newly discovered Jiaguan Formation(Lower Cretaceous) tracksite from the Linjiang region of Guizhou Province, China, reveals the first example of a Cretaceous track morphotype attributable to the non-avian theropod ichnogenus Gigandipus, here named Gigandipus chiappei ichnosp nov. The theropod dominated locality also reveals the second report of the avian theropod ichnogenus Wupus, one of the largest avian traces currently known from the Lower Cretaceous. The Linjiang site provides evidence to support previous interpretations of a distinctive Lower Cretaceous theropod-dominated ichnofauna that was widespread in China and East Asia and highlights the similarity between Lower Cretaceous theropod ichnotaxa in East Asia and those found in the Lower Jurassic both in East Asia and elsewhere. These similarities in turn create various ichnotaxonomic challenges familiar to researchers working on theropod tracks, and we recommend caution in the naming of new theropod ichnotaxa at the ichnogenus level.     

山东诸城地区蜥脚类恐龙足迹研究

蜥脚类恐龙是中生代时期陆地上最大的动物,作为广泛分布于侏罗纪和白垩纪的一种进化十分成功的恐龙,蜥脚类足迹也是分布较广,从早侏罗世到晚白垩世的地层中都有发现。诸城地区南部皇龙沟莱阳群、北部张祝河湾及棠棣戈庄大盛群中发现了三处早白垩世时期数量不等的恐龙足迹化石,这三处化石点都发现了蜥脚类的恐龙足迹化石。诸城地区三处的蜥脚类恐龙足迹之间有什么异同呢?这些足迹的造迹者都属于同一种蜥脚类恐龙吗?本文在大量的数据统计基础上,根据前后足的面积比对蜥脚类足迹进行了初步分类,推测早白垩世早期的皇龙沟及早白垩世晚期的棠棣戈庄都至少生活有两种不同的蜥脚类恐龙,证实了蜥脚类群居生活的特性。对三处不同时期蜥脚类恐龙体型的对比总结出蜥脚类体型趋小化的演化趋势,并分析认为环境的变化是演化的动力机制。对白垩纪恐龙物种的更替,古环境变化等多方面问题进行了探讨。