Non-marine selachians from the basal Cretaceous of Charente,SW France     

《Cretaceous Research》2013

A gypsum quarry at Cherves-de-Cognac in south-western France exposes a large section of Berriasian (basal Cretaceous) sediments deposited in a lagoonal environment. The sediments have yielded rich vertebrate faunas, but only two species of selachians are present; the lonchidiid hybodont Parvodus celsucuspus sp. nov. and the batoid Belemnobatis variabilis. The composition of the fauna, including only a single, seemingly endemic, hybodont species from a time when hybodont faunas are relatively well investigated in Europe, indicate that small hybodonts were not able to migrate longer distances. The recorded batoid species also occurs in southern England, demonstrating that these batoids were primarily marine fishes that regularly explored areas with reduced salinity.  相似文献   

Osteology and ontogeny of Early Cretaceous Philydrosaurus (Diapsida: Choristodera) based on new specimens from Liaoning Province,China     

《Cretaceous Research》2013

Choristoderes are a group of extinct diapsid reptiles that once occupied the freshwater systems in the Northern Hemisphere from the Middle Jurassic through the Miocene. The Early Cretaceous monjurosuchid Philydrosaurus from western Liaoning, China, represents a transitional morphotype between a broad-snouted (crocodile-like) and a narrow-snouted (gavial-like) skull during the evolution of Choristodera. New specimens of the taxon from the Early Cretaceous Jiufotang Formation include an incomplete braincase and a nearly complete juvenile skeleton; the study of these specimens provides new information on the braincase and ontogenetic change of the skeleton of this transitional monjurosuchid. In the braincase floor, the foramen internus canalis caroticus externus opens in a groove lateral to the constricted lateral aspect of the parasphenoid, and ventral exposure of this foramen differs from Champsosaurus, in which parasphenoid/pterygoid fusion completely encloses the canal. On the occiput, the vagus nerve foramen penetrates the basioccipital, while the two foramina for the hypoglossal nerve open at the exoccipital/basioccipital suture. Comparative study of the new juvenile specimen with adult Philydrosaurus reveals previously unknown developmental changes of the cranial and postcranial skeleton of this monjurosuchid. Ontogenetically, Philydrosaurus underwent a dramatic change of skull proportions, including elongation of the antorbital and postorbital regions, and elongation of the jaws, with a great increase of the number of marginal teeth. The lower temporal fenestra is entirely closed in early ontogeny, as in large, fully-grown adults.  相似文献   

Exceptionally favourable life conditions for macrobenthos during the Late Cenomanian OAE-2 event: Ichnological record from the Bonarelli Level in the Grajcarek Unit,Polish Carpathians     

《Cretaceous Research》2013

Pelagic and hemipelagic sediments of the Bonarelli Level (uppermost Cenomanian) in the Sztolnia section (Grajcarek Unit, Polish Carpathians) contain trace fossils of the Zoophycos ichnofacies, including (in descending order of abundance): Chondrites (smaller and larger forms), Planolites, Thalassinoides, Palaeophycus, Taenidium, Teichichnus, and Zoophycos. They occur in thick bioturbated layers, which are interbedded with rare, thin layers of unbioturbated black shales. The black shale layers mark the Bonarelli Level and are interpreted as a record of anoxia or dysoxia. Coeval sections in the Western Tethys contain similar trace fossils but they are less abundant and these sections are characterized by thicker unbioturbated black shale layers and thinner bioturbated layers. This confirms the exceptionally favourable life conditions in sediments of the Sztolnia section, which do not record strong global anoxia during the OAE-2 event. Such favourable conditions were probably caused by effective oxygenation of pore waters and deep burial of organic matter, which are a consequence of high rates of accumulation and the palaeogeographical location of the section on a flank of a submarine high, under strong circulation.  相似文献   

The taxonomic identity of a nearly complete ankylosaurid dinosaur skeleton from the Gobi Desert of Mongolia     

《Cretaceous Research》2013

Mongolian Paleontological Center (MPC) 100/1305 is one of the most complete ankylosaurid skeletons ever collected, and includes much of the postcranial skeleton and numerous in situ osteoderms. This specimen has been referred to Saichania chulsanensis, based on the similarity of the skull compared to the holotype of Saichania, MPC 100/151. However, MPC 100/1305 does not include a skull, and so referral of MPC 100/1305 to Saichania must be based on postcranial characters. Comparison of the postcrania of MPC 100/1305 and MPC 100/151 reveals several differences in the scapula, humerus, and metacarpals, indicating that MPC 100/1305 should not be referred to Saichania. Additionally, although it was previously reported that MPC 100/1305 was collected from the Baruungoyot Formation at Khulsan in Mongolia, collection records indicate that this specimen was instead collected from the Djadokhta Formation at Zamyn Khond. Two ankylosaurid species are known from the Djadokhta Formation of Mongolia and China, Pinacosaurus grangeri and P. mephistocephalus. There are no diagnostic characters in MPC 100/1305 that can be used to refer this specimen to P. grangeri or P. mephistocephalus, and there are a few differences between MPC 100/1305 and Pinacosaurus, such as the number of caudal vertebrae, and morphology of the coracoid, which have uncertain taxonomic implications. At present, MPC 100/1305 is best referred to Ankylosauridae indet., or cf. Pinacosaurus, based on its generally congruent morphology with Pinacosaurus and its provenance from the Djadokhta Formation, in which Pinacosaurus is the only recognized ankylosaurid taxon.  相似文献   

A revision of the putative Late Cretaceous triconodonts from South America     

《Cretaceous Research》2013

Austrotriconodon mckennai and Austrotriconodon sepulvedai, from the Campanian Los Alamitos Formation, Patagonia, Argentina were originally described as triconodont mammals and the sole members of the family Austrotriconodontidae. These mammals were represented by isolated cheek teeth originally regarded as molariforms, but their peculiar morphology later raised doubts about their purported triconodont affinities. Nevertheless, the morphological bases supporting the alternative taxonomic views have not been fully documented. We present here detailed comparisons of Austrotriconodon with other Late Cretaceous taxa and conclude that Austrotriconodon specimens should be assigned to Meridiolestida and Mesungulatoidea. These isolated teeth are likely premolars and might represent unknown dental positions of already described species or correspond to taxa that are yet to be formally recognized. According to our interpretation, there is still no record of Cretaceous triconodonts in South America, but we support the triconodont affinities for Jurassic taxa from the Cañadón Asfalto Formation in central Patagonia.  相似文献   

A new polyglyphanodontine lizard (Squamata: Borioteiioidea) from the Late Cretaceous Iharkút locality (Santonian,Hungary)     

《Cretaceous Research》2013

In recent years the Late Cretaceous (Santonian) terrestrial vertebrate locality at Iharkút (western Hungary) has yielded well-preserved remains of lizard taxa besides the remains of fishes, amphibians, turtles, crocodiles, pterosaurs and dinosaurs. Previously the polyglyphanodontine lizard Bicuspidon aff. hatzegiensis has been reported from Iharkút. However, recent excavations at this site produced more lacertilian remains including new polyglyphanodontine material, namely a maxilla and two dentaries which suggest the presence of a new genus in the Iharkút fauna. This previously unknown lizard (described here as Distortodon rhomboideus n. g. n. sp.) is distinct from other polyglyphanodontines such as Bicuspidon, Paraglyphanodon, Polyglyphanodon, Dicothodon and Peneteius. It differs from these genera mainly in having the lingual cusp situated more distally compared to the labial one on its bicuspid teeth located in the distal part of the tooth row, thus the crowns having a unique rhomboidal shape in occlusal view. Distortodon rhomboideus further strengthens the dominance of borioteiioid lizards in the Iharkút fauna. The growing presence of borioteiioids in European localities supports previous theories which suggest some paleobiogeographic connections between the western Tethyan archipelago and North America in the Late Cretaceous.  相似文献   

甘肃张掖地区白垩系风成砂岩沉积序列! 祁连山白垩纪隆升的沉积学响应   总被引：2，自引：1，他引：1       下载免费PDF全文

梅冥相  苏德辰 《古地理学报》2014,16(2):143-156

白垩纪祁连山隆升过程及其沉积学响应的研究,对认识青藏高原的形成及其环境效应具有重要意义。受控于祁连山隆升过程的甘肃张掖地区下白垩统,包括赤金堡组、下沟组和中沟组,其基本特征是：（1）分布局限而且厚度上千米的赤金堡组,主要由旋回性发育的“冲积扇（或洪积扇—辫状河—滨湖相风成沙丘”序列所组成,形成一种反映了“雨影效应”的粗碎屑岩序列;（2）下沟组总体为一套红层沉积,在盆地边缘发育更多的风成沙丘,可能代表了与祁连山更加快速隆升相对应的更加强烈的“雨影效应”时期的产物;（3）中沟组,从冲积体系演变为一个分布广泛的湖泊沉积体系,总体上属于潮湿气候背景下未受到“雨影效应”影响的产物,与祁连山均衡抬升存在成因联系;（4）研究区上白垩统总体缺失,可能与祁连山的卸载过程产生的山前地壳均衡反弹存在关联。因此,从赤金堡组到下沟组的风成砂岩序列、特殊的沉积相构成及其演化序列,不但成为窥视早白垩世祁连山隆升过程的物质记录,而且为早白垩世东亚大气环流格局的重建提供了另外一个重要的物质记录。  相似文献   

辽宁桓仁地区八里甸子一带早白垩世侵入岩与矿产的关系     

雷广新  程培起  王烜  鲁全  王海鹏  石林  吴子杰  陈佩佩  刘富 《地质与资源》2014,23(Z1)

八里甸子地区锆石SHRIMP U-Pb年龄为(123.6±2.1)Ma和(126.0±2.8)Ma的早白垩世侵入岩发育.研究表明,岩石为高硅,富钾、钠,低钙、铝、镁的碱钙性—钙碱性系列岩石.微量元素相对高Rb、Sr、Th、Ta、Nb、Pb、Zn、Cu、Ag等碱性元素.以轻稀土富集重稀土亏损为特征.岩石经历了较强的分异作用,是地壳发展演化成熟阶段产物.通过早白垩世侵入岩的岩石学、岩石地球化学与成矿的相关性分析认为:八里甸子地区早白垩世各岩体均为矿化岩体,易形成金矿化,其中钾长花岗岩易形成铅锌矿化、磷钇矿化,是该区寻找金、铅锌和稀土等矿产的重要地区.  相似文献   

辽宁建昌发现早白垩世Eosestheria新种     

高福亮  ;董洪年  ;张国仁  ;潘玉启文  ;王炬  ;吴子杰  ;穆亚男 《地质与资源》2014,23(6):539-542

在辽宁省建昌县古生物化石调查过程中,在建昌县大三家子西北下白垩统九佛堂组下部采集了个体长4.3 cm,高1.6 cm的特大类型Eosestheria新种——建昌东方叶肢介(Eosestheria jianchangensis).该新种在建昌县首次发现,世界少有.  相似文献   

Features and buried environment analysis of fossils specimens in Shuangmiao region of Kazuo County in Liaoning Province     

YAO Yonglong 《中国地质调查》2014,7(3):61-66

In order to ascertain the species, quantity and occurrence layers of the fossils specimens in Shuangmiao region of Kazuo County, the authors harvested lots of Mesozoic fossils such as reptiles,birds,fishes and plant species, through geological surveys, section measurements and excavations. According to the comparison between the measured section and typical section, it is concluded that the fossil-bearing stratum is the No.1 Member of Jiufotang Formation, which belongs to the lacustrine facies. This research enriches the Mesozoic fossils data of Western Liaoning Province.  相似文献