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1.
Teeth of a new species of hybodont shark Vectiselachos (Chondrichthyes: Lonchidiidae) are described from the late Aptian (Early Cretaceous) of southern England. Vectiselachos gosslingi sp. nov. has very distinctive coarse striations that form raised ridges over the occlusal surfaces of the crown. 相似文献
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《Proceedings of the Geologists' Association. Geologists' Association》2017,128(4):599-612
Early Cretaceous sediments of Aptian–Albian age outcrop at Munday’s Hill Quarry, Bedfordshire, England. Previous papers describing the section have resulted in different terminologies being applied. The Lower Cretaceous in Bedfordshire is represented by sediments belonging to the Lower Greensand Group and the Gault Clay Formation. Within the Lower Greensand Group in the study area the Woburn Sands Formation, are of Aptian–Albian age. Selected samples have been analysed for palynology. The analysis reveals diverse palynomorph assemblages, including well-preserved dinoflagellate cysts and sporomorphs. Comparison of the assemblages with published records indicates that the lower samples are of Late Aptian age. Forms recorded include common Kiokansium unituberculatum, Cerbia tabulata, Aptea polymorpha and Cyclonephelium inconspicuum. An Early Albian age is indicated for the uppermost sample. 相似文献
4.
Jean-Paul Billon-Bruyat Jean-Michel Mazin Joane Pouech 《Swiss Journal of Geoscience》2010,103(2):143-153
The spotty nature of the terrestrial fossil record for the Mesozoic hinders a more complete understanding of dinosaur diversity. For stegosaurs (Ornithischia), the plated dinosaurs, only a few and fragmentary remains are reported from the Early Cretaceous of Europe. A recent revision concluded that only a partial vertebra of the nomen dubium Craterosaurus (?Aptian, England) could be considered as stegosaurian. Here we report on a stegosaur tooth from the Early Cretaceous (Berriasian) Purbeckian deposits of Cherves-de-Cognac (Charente), southwestern France. This tiny tooth was examined in detail using microtomography. Comparisons being limited by the rarity of stegosaur tooth rows material (e.g., from the skull of the holotype of Stegosaurus stenops) and dental material, notably from Europe, we observed new material of cf. Stegosaurus armatus and Hesperosaurus mjosi from the Upper Jurassic Morrison Formation of Wyoming (USA). The tooth shows the most similarities to the Late Jurassic genera Stegosaurus and Hesperosaurus, but differs in having a distinctive downwardly arched (V-shaped) cingulum on the ?lingual face (maxillary tooth hypothesis). It is referred to as Stegosauria indeterminate, a medium-sized quadrupedal herbivore that inhabited an emerged land between the Armorican Massif and the Massif Central. This finding is the first evidence of a stegosaur from the Early Cretaceous of France and a welcome addition to the meagre European record of that time. In addition, it is the second stegosaurian tooth crown reported from Europe. The assemblage of ornithischians of Cherves-de-Cognac shares some similarities with that of the Early Cretaceous (Berriasian) of the Purbeck Limestone Group, southern England. The relative rarity of ornithischian osteological remains in both Purbeckian environments suggests that most of these dinosaurs were mainly inhabitants of inland terrestrial palaeoenvironments. 相似文献
5.
The Early Cretaceous was a time with super-greenhouse conditions and episodic global oceanic anoxic events. However, relative timing of atmospheric CO2 emissions and oceanic anoxic events, and their causal relationships remain matters of debate. Using the stomatal index approach, well-preserved fossil cuticles of Ginkgo from the Lower Cretaceous Changcai Formation, eastern Jilin, and from the Lower Cretaceous Yingcheng Formation, central Jilin, Northeast China, were investigated to reconstruct atmospheric CO2 concentrations during the Aptian and earliest Albian (Early Cretaceous). The results indicate that the CO2 concentrations reached 1098–1142 ppmv (Carboniferous standardization) or 970–1305 ppmv (regression function) during the Aptian and earliest Albian. Our estimates of palaeoatmospheric CO2 concentrations during the earliest Albian (OAE 1b) are slightly higher than the data between the early Aptian Selli (OAE 1a) and the middle Aptian Fallot OAEs; this may indicate the absence of any great emissions of CO2 during the latest Aptian and earliest Albian. 相似文献
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《Journal of Asian Earth Sciences》2002,20(3):277-287
Radiolarian biostratigraphic research has been carried out along two continuous sections through the Xialu Chert, one of the accreted sheets included in the Yarlung-Zangbo Suture Zone. Six radiolarian zones have been identified as follows: Laxtorum(?) jurassicum Zone (Aalenian), Tricolocapsa plicarum Zone (Bajocian–lower Bathonian), Stylocapsa(?) spiralis Zone (upper Callovian–Oxfordian), Hsuum maxwelli Zone (Kimmeridgian), Pseudodictyomitra carpatica Zone (upper Tithonian–lower Valanginian), and Turbocapsula costata Zone (Aptian).A reconstructed stratigraphy of the Xialu Chert, based on lithological succession and radiolarian dating, indicates that the chert exhibits a long depositional history, at least from early Middle Jurassic (Aalenian) to late Early Cretaceous (Aptian). The separation of the Lhasa Block from the northern Gondwana margin must, therefore, be dated before the Aalenian. The absence of calcareous sediments in the Xialu Chert indicates that the oceanic basin was deeper than the CCD throughout the depositional history. The transition from chert to siliceous mudstone is recorded sometime in Early Cretaceous, most probably around the Barremian/Aptian boundary. This means that the oceanic plate had already started being consumed at a trench by that time. The accretion of the Xialu Chert occurred after the Aptian time. 相似文献
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Tatiana A. Kovaleva Valentina S. Markevich Ge Sun 《Russian Journal of Pacific Geology》2017,11(3):178-190
The taxonomic composition of the palynological assemblage of the Dongning Formation is supplemented. The palynological assemblage corresponds to those from the Lipovtsy Formation (Aptian) in the Razdolnaya Basin of Primorye (Russia) and the Muling Formation (Aptian) in the Jixi Basin of eastern Heilongjiang (China). It is found that the age of the Dongning Formation is Aptian. The palynological assemblage is characterized by dominance of spores of Gleicheniaceae; they are accompanied by spores of Cyatheaceae. The most important feature of the palynological assemblage of the Dongning Formation is the presence of angiosperm pollen (Tricolpites sp., T. micromunus, T. vulgaris, Retitricolpites georgiensis, R. vulgaris, Clavatipollenites hughesii, Quercites sparsus, Fraxiniopollenites variabilis). 相似文献
8.
Jayasri Banerji 《Cretaceous Research》2000,21(6):781
An angiosperm fruit of uncertain affinity and a questionable flower are reported from the Rajmahal Formation (Early Cretaceous) at the locality of Sonajori, Rajmahal Basin. The remains of ferns, Pentoxylales and conifers have been described previously from this locality. The significant addition of angiosperm megafossil remains confirms that flowering plants were evolving during the Early Cretaceous Epoch in India. The Sonajori assemblage seems to be the youngest fossil assemblage recovered so far from the Rajmahal Basin. It is tentatively dated as Barremian–Aptian. 相似文献
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The chronostratigraphic framework of the non-marine deposits of the Central Tunisian Lower Cretaceous (Kebar Formation) is reviewed from a biostratigraphic viewpoint. The outcrops located in the Jebel Kebar, Jebel Ksaïra and Jebel Koumine localities provided charophyte assemblages belonging to two biochronozones: Ascidiella cruciata-Pseudoglobator paucibracteatus (upper Barremian–lower Aptian) and Clavator grovesii lusitanicus (upper Aptian–lower Albian). Clavatoraceans from the upper Barremian–lower Aptian in the Tunisian Atlas are reported here for the first time. The assemblage consists of Atopochara trivolvis var. triquetra, Ascidiella iberica var. inflata, Globator maillardii var. trochiliscoides, Globator maillardii var. biutricularis, Echinochara peckii var. lazarii, Clavator harrisii var. harrisii and Clavator harrisii var. reyi. In addition, a new characean species, Mesochara magna nov. sp. Trabelsi and Martín-Closas, is described herein. The results show that the Kebar Formation is diachronous in Central Tunisia, with a more complete record to the north (Jebel Koumine) than in the type locality (Jebel Kebar). Barremian–Aptian diapiric activity is proposed as the factor that controls the diachronous nature of this formation.The late Barremian–early Aptian charophyte assemblages from the Kebar Formation display strong affinities with the contemporaneous floras of the European basins, thus suggesting that intense supraregional floristic exchanges occurred between the Tethyan islands scattered throughout what is now Western Europe and North Africa. The biogeographic distribution of these charophytes leads to the hypothesis that the peri-Tethyan Archipelago acted as an effective bridge for the intercontinental exchanges of these plants between Laurasia and Gondwana. 相似文献
10.
The angiosperm pollen record from the Anfiteatro de Ticó and Punta del Barco formations (Baqueró Group) is reported. The relevance of these floras is that they are accurately dated as late Aptian, and one of the oldest floras southern South America with fossil angiosperms. Twelve samples were studied, showing Clavatipollenites and Retimonocolpites as dominant types. A new species, Jushingipollis ticoensis sp. nov., is proposed. A doubtful angiosperm pollen grain, Lethomasites sp., is also identified and described. A multivariate analysis of similarities between different Early Cretaceous angiosperm pollen assemblages suggests that the Baqueró Group assemblages have great similarities with other coeval units from Argentina, Australia and United States, which were located in a similar paleolatitude. 相似文献
11.
Jean Marcoux Jacques Girardeau Eric Fourcade Jean-Paul Bassoullet Jean Philip Michel Jaffrezo 《Geodinamica Acta》2013,26(4-5):313-325
Abstract— The Lhasa Block (s.l.) is bounded to the South by the Tertiary Yarlung Zangbo suture zone and to the North by the terminal Jurassic/earliest Cretaceous Bangong Nu Jiang suture zone. Several tectonostratigraphic units have been recognized in the central-northern part of the Lhasa Block. These are from bottom to top : 1) a thick turbiditic series with a few lenses of allodapic limestones which have yielded an Aalenian — Bajocian foraminiferal assemblage. This series is tectonieally overlain by the Donqiao ophiolite; 2) the continental to shallow marine late Malm to lowermost Cretaceous Zigetang Formation which disconformably overlies the Donqiao ophiolite and 3) continental red detrital rocks or marine Early/Late Aptian boundary to Early Albian foraminifera-rich bedded limestones in which some volcanic rocks are locally interbedded.We discuss the palaeogeographical distribution and biostratigraphical meaning of some foraminifera (Gutnicella cayeuxi (LUCAS), Palorbitolina fen<ícu/o?(Bl .LMKNBACIl), Praeorbitolina cormyi SCHROEDER and Palor-bilolmoides hedini CHREREHI and ScilKOKDK.lt) and their bearing on the radiometric age of the Aptian-Albian boundary. 相似文献
12.
Early Cretaceous elasmobranchs still are very insufficiently known despite all progress that has been accomplished in recent years. Here, a small elasmobranch assemblage is presented from the Valanginian of Austria that contributes significantly to a better understanding of early Cretaceous elasmobranch diversity. The new assemblage comprises two new carcharhiniform sharks, Altusmirus triquetrus gen. et sp. nov. and Fornicatus austriacus gen. et sp. nov., a new orectolobiform shark, Similiteroscyllium iniquus gen. et sp. nov., and a galeomorph shark tooth of uncertain affinities. The recent identification of Similiteroscyllium gen. nov. has shown that it has strong similarities with Ornatoscyllium rugasimulatum from the Lower Cretaceous of France. Significant differences of the tooth morphology of O. rugasimulatum and the type specimen O. freemani justify full reconsideration of the systematic position of O. rugasimulatum and require it to be reassigned to Similiteroscyllium gen. nov. described in this paper. The new assemblage described here, and those from the Valanginian of France and Poland comprising 30 additional taxa, indicates that Early Cretaceous elasmobranch diversity was significantly higher than previously assumed. Consequently, the supposed diversity decline of elasmobranchs across the Jurassic-Cretaceous boundary represents a collecting bias rather than a real pattern. 相似文献
13.
《Proceedings of the Geologists' Association. Geologists' Association》2023,134(3):276-282
Rare, isolated teeth of Corysodon multicristatus sp. nov. are described from two levels in the Atherfield Clay Formation (Early Aptian, Early Cretaceous) of Atherfield Point on the Isle of Wight, UK. Ten teeth of the new species were recovered from 1095 kg of washed and graded sediment residues. The teeth themselves are very small (around 0.5 mm high) and possess a distinctive crown bearing a tiered series of transverse crests adapted for rasping. Details of the dental architecture of the Atherfield Clay Formation specimens clearly indicate that the Cretaceous material differs significantly from the teeth of the type species for the genus, Corysodon cirinensis, recorded from the Kimmeridgian of northern France and Switzerland. C. multicristatus is the first substantiated record of the genus from the Early Cretaceous, thereby extending the stratigraphic range of the genus from the latest Jurassic, and the geographical range from continental Europe to the UK. 相似文献
14.
The Penninic Ocean was a side tract of the Central Atlantic Oceanic System intercalated between the European and the Austroalpine plates. Its closure started in the Early Cretaceous, as subduction of the oceanic crust beyond the Austroalpine plate. The sedimentary change on the Austroalpine shelf from pelagic carbonates into deep-water siliciclastics correlated with the denudation of the accretionary wedge resulting from that subduction. Within the Bajuvaric Unit of the Upper Austroalpine, this transition is reflected by the lithostratigraphic boundary between the older Schrambach and the younger Tannheim Formation. This boundary is well exposed in a newly discovered site at Sittendorf, southwest of Vienna. This new outcrop yields an extraordinarily rich planktonic foraminifera assemblage characterized by typical Aptian species belonging to Blowiella, Globigerinelloides, Hedbergella, Leupoldina, and Praehedbergella. A detailed biostratigraphic analysis based on thin-section investigations precisely dated the lithostratigraphic boundary within the lower part of the early Aptian Leupoldina cabri Acme Zone, having an approximate age of 123 Ma. Along with the biostratigraphic analyses, the gamma-log outcrop measurement was a powerful tool in interpreting the stratigraphy and the tectonic setting in the outcrop, which intersects one smaller-scale isoclinal fold. 相似文献
15.
A new genus and species of cyathealean fern, Yavanna chimaerica gen. et sp. nov., is erected for several permineralized stems recovered from the Early Cretaceous (Aptian) Cerro Negro Formation, which crops out at the South Shetland Islands, Antarctica. The new species is characterized by solenostelic erect stems with medullary bundles traversing the pith, and surrounded by persistent petiole bases and adventitious roots. Proximal petiole bases present a one-parted modified omega-shaped trace, which becomes three-parted distally. The anatomy of the new fern show similarities with both Thyrsopteris elegans Kunze and with the Cyatheaceae s.s., suggesting that it is a representative of an extinct lineage among the Cyatheales. 相似文献
16.
This work is a study of the ammonite record of a new stratigraphic section of Aptian age, at the Mina Texali (Puebla State, Central Mexico). A detailed biostratigraphic analysis was carried out on 309 specimens systematically sampled on a bed-by-bed basis. An Aptian ammonite zonation is proposed for the Mina Texali (= MT) section with two interval zones, Dufrenoyia justinae and Caseyella sp., and one informal biostratigraphic unit represented by the Huastecoceras trispinosoides beds. We also analyze the taxonomic composition, paleoecology and some systematic issues of the ammonite record of the MT section. The first record in Mexico of the genera Pseudosaynella, Xerticeras and the nautiloid Heminautilus is identified in this section. The ammonite assemblage is assigned to the proximal part of the outer neritic region of the continental shelf. The ammonite record of the studied section is diagnostic in establishing the lower-upper Aptian transition, and the local zonation of the MT provides important data for the development of an Aptian standard ammonite zonation for the Central Atlantic province. 相似文献
17.
Masoumeh Molaei Seyed Hamid Vaziri Morteza Taherpour-Khalil-Abad Jafar Taheri 《Arabian Journal of Geosciences》2017,10(14):317
Neotrocholina Reichel, 1956 is one of the most important benthic foraminifera in Early Cretaceous. Some of the species of this genus are indexes in biostratigraphy especially for this interval (e.g., Neotrocholina friburgensis: Late Barremian–Early Aptian; Neotrocholina aptiensis: Early Aptian). In order to conduct accurate paleontological investigations, sampling from the carbonate units of the Tirgan Formation in Kopet Dagh sedimentary basin is done. According to the occurrence level in the studied stratigraphic sections as well as biometric interpretations, two species of this genus (N. friburgensis and Neotrocholina valdensis) are pointed out. 相似文献
18.
中国甘肃省酒泉地区公婆泉盆地早白垩世恐龙化石 总被引：2，自引：0，他引：2
中国甘肃省酒泉地区公婆泉盆地下白垩统新民堡群的恐龙化石主要由1992年中日丝绸之路恐龙考察计划和1997~2000年中美马鬃山恐龙考察计划发掘和研究。先后发现的恐龙包括兽脚类、蜥脚类、禽龙类和新角龙类等。这一新的公婆泉恐龙组合的主要特征是同时包含了在晚白垩世占主导地位的几类恐龙的基干分子,如戈壁巨龙(Gobititan)是巨龙型类的基干分子,马鬃龙(Equijubus)是鸭嘴龙型类的基干分子,而古角龙(Archaeoceratops)和黎明角龙(Auroraceratops)是新角龙类的基干分子。公婆泉恐龙组合的另一特征是其某些成员的体型较大,如似鸟龙类和镰刀龙类恐龙是同期同类中最大的。比较研究发现,公婆泉盆地新民堡群的恐龙和辽西热河群的恐龙关系密切,但前者的整体来说要比后者进步。考虑到公婆泉盆地新民堡群的时代(Albian)较辽西热河群(Hauterivian晚期-Aptian早期)晚,公婆泉恐龙组合似应代表中国北方早白垩纪鹦鹉嘴龙恐龙动物群进化过程中较进步的一个阶段。 相似文献
19.
Angiosperms began to colonise riparian habitats very soon in their evolutionary history, probably already in the Aptian, but it is still poorly known when flowering plants finally dominated entirely these kind of communities as they do in the present. A new fossil plant locality (Molí del Baró-1) from the upper Maastrichtian of the Southern Pyrenees is described in which meandering river facies represent one of the first riparian communities formed only by angiosperms. The fossil assemblage consists of abundant leaves, seeds, logs and sporomorphs. Angiosperms remains dominate in all these cases and the leaf sample is mostly composed of a new eudicot willow-like species, Saliciphyllum gaetei sp. nov., the palm Sabalites longirhachis and an helophytic monocot. Pollen remains suggest that the later belonged to Typhaceae. Most of these plant remains were parautochthonous and deposited in a pond formed in the accretional part of a meander loop. The locality of Molí del Baró-1 represents an unique plant fossil assemblage in the uppermost Cretaceous of southern Europe. It clearly differs from those reported in other Maastrichtian localities of the Pyrenees (Fumanya and South Isona) and from the Campanian-Maastrichtian of Austria and Romania. In addition, it reflects a surprisingly modern physiognomy for a Late Cretaceous riverine plant assemblage that was built up with willow-like plants, palms and reeds. 相似文献
20.
A taxon of the Stenophlebiidae, Yixianstenophlebia magnifica gen. et sp. nov., is described from the Lower Cretaceous Yixian Formation at Liutiaogou, Ningcheng County, Inner Mongolia of China. Its closest relative is the Late Jurassic European genus Stenophlebia. This new discovery is helpful to understand the Jehol Biota assemblage at Liutiaogou Locality. It also confirms that the Stenophlebiidae was a very diverse and widespread family during the Early Cretaceous. The causes of its extinction in the Late Cretaceous remain enigmatic. 相似文献