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1.
Sediments of Early Aptian age in Bulgaria can be assigned to four different facies: platform carbonates (Urgonian complex), shallow-water siliciclastics, hemipelagic and flyschoid siliciclastics. The taxonomic analysis of the ammonite faunas of 18 sections from these four different facies resulted in a revision of the existing ammonite zonation scheme so far applied in Bulgaria and adjoining areas. A new biostratigraphic scheme, which bridges the western and eastern Tethys, is thereby proposed for the Lower Aptian of Bulgaria.The Upper Barremian Martelites sarasini Zone is characterized in its upper part by the Pseudocrioceras waagenoides Subzone in the shallow-water sections and by a horizon with Turkmeniceras turkmenicum in the deep-water settings. The Upper Barremian/Lower Aptian boundary is fixed by the first appearance of Paradeshayesites oglanlensis. For the Lower Aptian the following ammonite zones were established (from bottom to top): The Paradeshayesites oglanlensis Zone, the Deshayesites forbesi Zone (= formerly Paradeshayesites weissi Zone) including the Roloboceras hambrovi Subzone in the upper part, the Deshayesites deshayesi Zone including the Paradeshayesites grandis Subzone in the upper part and the Dufrenoyia furcata Zone. The Lower–Middle Aptian boundary has been defined by the appearance of species belonging to the genera Epicheloniceras and Colombiceras.The Lower Aptian ammonite faunas of Bulgaria, allow an interregional correlation with other areas of the Tethyan Realm. The presence of Turkmeniceras in the Upper Barremian enables a correlation with the Transcaspian region, whereas Roloboceras, Koeneniceras and Volgoceratoides found in the middle part of the Lower Aptian are more typical representatives of the ammonite faunas in northern Europe (England, Germany, Volga region).The analysis of the ammonite successions in combination with sedimentological observations enable us to conclude that the marls and marly limestones of the Lower Aptian studied here also cover the interval of the Oceanic Anoxic Event 1a. An interval of thin-laminated clays, rich in organic matter, was identified in the upper part of the D. forbesi Zone (Roloboceras hambrovi Subzone). This interval is characterized by a total lack of benthic faunas. 相似文献
2.
The fossil clam shrimp genus Xibeiestheria Wang in Shen et al., 1982, a component of the well-known Early Cretaceous Yanjiestheria fauna, was originally described from the lower Aptian Jingchuan Formation of Yanchi County, Ningxia Hui Autonomous Region of northwestern China. The morphological re-examination under an SEM of the holotype of the type species Xibeiestheria pora Wang in Shen et al., 1982 has revealed new taxonomic features not previously recognized. These include: (1) growth lines with serrated lower margins, having a row of small pores; (2) widely spaced radial lirae intercalated cross bars on growth bands in the dorsal part of the carapace; (3) fine reticulum occurring within coarse reticulation on growth bands in the middle part of the carapace; (4) puncta radially aligned along the widely spaced radial lirae on growth bands in the lower part of the carapace. 相似文献
3.
Mathesia darderi, a slender cylindrical monopleurid genus, formerly documented from the late Aptian-Albian of Spain, France, Tunisia, Algeria, Egypt and Turkey, has been discovered in the upper Barremian and the lower Aptian of Bulgaria and Spain. Notwithstanding some morphological changes, Barremian-lower Aptian forms and those of the upper Aptian-Albian possess the same myocardinal organisation and the same microstructural attributes. The inner shell margin of the right valve displays scalloped, festooned, tubular and vermiform microstructures. The most prominent evolutionary trait of M. darderi is the increase in body size through time. A statistical analysis of size distributions show that populations of the late Barremian-early Aptian, and the late Aptian, and those of the early to middle Albian, are significantly different; a pattern which has a biostratigraphic potential. Ecological changes through time are expressed by a displacement of communities from the central/distal part, to the proximal part of carbonate platforms. M. darderi is present locally in the upper Barremian-lower Aptian, and has its major spreading over the European and Arabo-African margins of the Mediterranean Tethys during the Clansayesian-lower to middle Albian. The disappearance of the species at the Middle-Upper Albian boundary, correlates with a critical, spatial reduction of carbonate platforms. 相似文献
4.
Michael E. Burns Philip J. CurrieRobin L. Sissons Victoria M. Arbour 《Cretaceous Research》2011,32(2):174-186
Four juvenile specimens referable to Pinacosaurus grangeri (Ankylosauria: Dinosauria) are described from the Campanian (Upper Cretaceous) locality Bayan Mandahu in northern Inner Mongolia Autonomous Region (People’s Republic of China). All the specimens preserve the skulls as well as, in some cases, mandibles, postcrania, and osteoderm. They are not taphonomically deformed by expanding matrix distortion, unlike many Gobi specimens, including the holotype of P. grangeri. Bayan Mandahu is also the type locality for Pinacosaurus mephistocephalus. The proximity in space and time of these two closely related species warrants a generic and specific revision for Pinacosaurus. The distinction of the two species is based on characters of the squamosal dermal elaborations, cranial roof posterior to the orbits, premaxillary notch, and distal margin of the ilium. Although a relatively well-represented ankylosaur taxon, the phylogenetic position of Pinacosaurus has not been unequivocally resolved. A new analysis recovers Pinacosaurus as the most basal member of the Ankylosaurinae. 相似文献
5.
The fossil clam shrimp genus Cratostracus was first described from the Turonian–Coniacian (Upper Cretaceous) Qingshankou Formation in the Jilin and Heilongjiang provinces of China, and it has been found to range down into the Aptian Guantou Formation in Zhejiang Province of southeastern China. Recently, species tentatively attributable to it (Cratostracus? cheni) has been recorded in the well-known Jehol Biota bearing Barremian–lower Aptian (Lower Cretaceous) Yixian Formation in western Liaoning Province of northeastern China. The species described in this paper as Cratostracus? tunisiaensis sp. nov. was recovered from the Sidi Aïch Formation in the Chotts area of southern Tunisia. Although only tentatively attributed to Cratostracus, its occurrence is consistent with a Barremian (Early Cretaceous) age for the formation. This first direct dating of the Sidi Aïch Formation gives a valuable insight for the stratigraphy of the region and will make it possible to more precisely correlate the different outcrops of the Sidi Aïch Formation. Moreover, the new fossil discovery allows a reconstruction of the paralic ecosystem that characterized the study area during the Barremian. 相似文献
6.
Pachycephalosaurs, a group of ornithischian dinosaurs with distinctive cranial ornamentation and skull domes, underwent dramatic changes in cranial morphology during ontogeny. This has caused debate about whether some specimens belong to juveniles or adults, which impacts studies of pachycephalosaur phylogeny and evolution. One such debate concerns a small skull roof specimen from the Campanian (Upper Cretaceous) of New Mexico, NMMNH P-33898, which was originally described as an indeterminate juvenile but later regarded as a mature adult and erected as the holotype of a new small-bodied species, Stegoceras novomexicanum. We restudied NMMNH P-33898 using computed tomography scanning, morphometric and phylogenetic analyses, and comparisons to growth series of other pachycephalosaurs (Stegoceras validum, Pachycephalosaurus wyomingensis). We conclude that two purported paratype specimens of Stegoceras novomexicanum cannot be referred to the same taxon as the holotype, that the holotype and controversial paratypes all belong to immature specimens and not aberrant small-bodied adults, but that current evidence cannot clearly determine whether NMMNH P-33898 is a juvenile belonging to its own diagnostic species (S. novomexicanum) or is a juvenile of Stegoceras validum, Sphaerotholus goodwini, or another known taxon. We review the pachycephalosaur record of New Mexico and demonstrate that pachycephalosaurs were important components of dinosaur faunas in the southern part of Western North America during the ∼15 million years before the end-Cretaceous extinction, just as they were in roughly contemporaneous northern localities. 相似文献
7.
The Shah Kuh Formation of the Khur area (Central Iran) consists of predominantly micritic, thick-bedded shallow-water carbonates, which are rich in orbitolinid foraminifera and rudists. It represents a late(est) Barremian – Early Aptian carbonate platform and overlies Upper Jurassic – Barremian continental and marginal marine sediments (Chah Palang and Noqreh formations); it is overlain by basinal deposits of the Upper Aptian – Upper Albian Bazyab Formation. The lithofacies changes at both, the base and top of the Shah Kuh Formation are gradational, showing that the formation is part of an overall transgressive sedimentary megacycle, and that the formational boundaries are potentially diachronous on larger distances. Analyses of facies and stratal geometries suggest that the Shah Kuh carbonate system started as a narrow, high-energy shelf that developed into a large-scale, flat-topped rudist platform without marginal rim or steep slope. The Shah Kuh Platform is part of a large depositional system of epeiric shallow-water carbonates that characterized large parts of present-day Iran during Late Barremian – Aptian times (“Orbitolina limestones” of NW and Central Iran, the Alborz and the Koppeh Dagh). Their biofacies is very similar to contemporaneous deposits from the western Tethys and eastern Arabia, and they form an important, hitherto poorly known component of the Tethyan warm-water carbonate platform belt. 相似文献
8.
9.
A revised ammonoid biostratigraphy is presented for the Aptian of NW Africa, Essaouira-Agadir Basin (EAB), Morocco, based on detailed analysis of 5 key sections. A number of bio-events are documented and 26 genus and 43 species fully documented, forming the largest published Aptian ammonite collection made from NW Africa. The section at Tiskatine is documented as the type section, and 8 zones and subzones are defined, of which 5 are new. This work allows correlation of the Aptian of the EAB to the Standard Mediterranean Ammonite Scale (SMAS).Two main hiatuses are identified at the scale of the basin scale: a major one that includes most of the lower Aptian and the base of the upper Aptian and a second one encompass the top of the upper Aptian and the base of the lower Albian. The ammonite fauna displays a clear Tethyan palaeobiogeographic character affected by a fairly high degree of endemism at the genus and species level. The new genus and species Elsaisabellia tiskatinensis is introduced. 相似文献
10.
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
11.
Roque Aguado Jos Manuel Castro Miguel Company Gins Alfonso De Gea 《Cretaceous Research》1999,20(6):663
The Upper Barremian to Aptian Almadich Formation (Inner Prebetic Domain of the Betic Cordillera) is composed of hemipelagic sediments deposited on a distal carbonate ramp in the southern Iberian Palaeomargin. Within this facies we have found a thick interval of blue to black shales and marls that is interpreted as deposited under oxygen-depleted conditions. We think that this interval, dated as early Aptian, represents the local record of Ocean Anoxic Event 1a. The integrated biostratigraphic analysis of a section in the Almadich Formation, by means of planktonic foraminifera, calcareous nannofossils and ammonites, enables us to recognize most of the biostratigraphic units based on these three fossil groups and to correlate between them. The Sartousiana, Sarasini, Weissi, Deshayesi and Furcata (ammonite) Zones were identified for the Upper Barremian–Lower Aptian interval. By means of calcareous nannofossil biostratigraphy the Micrantholithus hoschulzii, Hayesites irregularis and Rhagodiscus angustus Zones, plus several additional biohorizons, were identified. A quantitative study performed on a set of 27 Lower Aptian samples has enabled the precise identification of the ‘nannoconid crisis’, the lower limit of which clearly precedes the main anoxic event, and its correlation with other bioevents. Planktonic foraminifera occur consistently throughout the Lower to Upper Aptian of the Cau section and are moderately well preserved. This fact allows us to use the most recent taxonomic framework, based on wall texture, to identify the Blowiella blowi, Schackoina cabri, Globigerinelloides ferreolensis, Globigerinelloides algerianus, Hedbergella trocoidea andTicinella bejaouaensis Zones. Coincident with the anoxic episode, the planktonic foraminiferal assemblages are composed of a significant number of forms with elongated chambers and/or tubulospines assigned to the genera Claviblowiella,Lilliputianella , Leupoldina and Schackoina. Most of the planktonic foraminiferal and nannofossil taxa are illustrated. 相似文献
12.
The orthopteran Parahagla sibirica Sharov, 1968 is reported based on a male forewing for the first time from the Lower Cretaceous Chijinbao Formation of the Jiuquan Basin, Gansu Province, Northwest China. The diagnosis of the species is revised based on the new specimen. Its palaeogeographic and stratigraphic distributions are discussed, based on which two possible migration paths of the species are indicated as follows: (1) This species initially appeared in northern Hebei and western Liaoning, China at latest in the earliest Aptian, and further migrated northwestwards to Transbaikalia and westwards to Gansu Province soon later (early-middle Aptian). (2) Or alternatively, it originally occurred in Transbaikalia earlier than the Aptian and further migrated southwards to northern China during the Aptian. 相似文献
13.
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
14.
The genus Horiopleura Douvillé is restricted to the Mediterranean and southwestern Asian regions, and is represented by eight species developed during the late Barremian–Albian. This revision of species contributed to delineate generic and specific characters. The definition of species is based on a set of external and internal qualitative and quantitative characters, the key characters being size, radial bands, ornamentation and the presence of a left posterior canal. Morphometry documents the dimorphism of some species, corroborated by regression analysis. Horiopleura dumortieri is an upper Barremian–lowermost Bedoulian species from SE France, Horiopleura brevis n. sp. is a Bedoulian, Mediterranean species, extending to the lower Gargasian, Horiopleura gigantea (pro Monopleura) is a Bedoulian species, restricted the Ukrainian Carpathes. Horiopleura lamberti and H. almerae are Upper Aptian to lower Albian species, and are known from Southern Europe and North Africa. Horiopleura haydeni is essentially late Aptian and typifies the southwestern Asia “Yasin fauna”. Horiopleura distefanoi and H. gemmellaroi (both formerly placed in Polyconites) are restricted to the Albian of the peri-Adriatic regions and North Africa, the former being present in the Middle East. Multiple correspondence analysis using six categorical variables and their categorical states, applied to the comparison of species, tends to corroborate our overall taxonomic frame-work, and reveals three groups of species with distinctive ages. 相似文献
15.
Lucy A. Muir Jason Dunlop Andrew Moore 《Proceedings of the Geologists' Association. Geologists' Association》2012,123(1):165-169
Rochdale Museum Service holds a large collection of fossils from the important Carboniferous site of Sparth Bottoms (Lancashire, UK; Middle Coal Measures). Several of these are type specimens donated by Harold Howard in 1939. These objects were stored in the museum basement for several decades, and were thought to have been lost. The types are the holotype of the scorpion Eobuthus holti Pocock, 1911 and the holotype of the crustacean Anthrapalaemon grossarti var. holti Woodward, 1911a. These species were not named after Howard, because the describers thought that Fred Holt was the rightful collector. The holotype of the myriapod Euphoberia woodwardi Baldwin, 1911 (put into synonymy with Palaeosoma robustum Baldwin, 1911) is known to have originally been in the collection, but was not located in a recent survey. 相似文献
16.
Jorge Dinis Jacques Rey Pierre-Charles de Graciansky 《Comptes Rendus Geoscience》2002,334(10):757-764
. Three transgressive–regressive 2nd-order cycles were identified in the Upper Aptian–Albian fluvial and marine deposits of the Lusitanian Basin. Its widespread nature, probably including eustatic origin, allows correlation between the southern package, with precise stratigraphic positioning, and the northern series with a poorly constrained age. The main unconformities can be related to the onset of an oceanic crust, in the western margin of Galicia during the Late Aptian, in the bay of Biscay during the Early Albian, and, to the northwest of the Galicia triple point, during the Middle to Late Albian transition, and, at the Albian–Cenomanian boundary, to a probable compressive event with Africa due to the rotation of Iberia. To cite this article: J. Dinis et al., C. R. Geoscience 334 (2002) 757–764. 相似文献
17.
The Lower and Upper Cretaceous deposits from the Brazilian marginal basins present a rich and diversified fauna of ostracodes in continental, marine and mixohaline paleoenvironments. While the Cretaceous ostracodes from the northeastern region have already been the subject of many taxonomic and biostratigraphical studies, data from the southeastern basins are still scarce and restricted to the record of a few species. The present study represents a comprehensive contribution to the systematic knowledge of the Aptian–Santonian ostracodes from the Brazilian southeastern marginal basins. A total of 1045 cutting samples were analyzed from 10 wells drilled offshore in Santos, Campos and Espírito Santo basins. Thirty-eight ostracode taxa were recorded from different depositional environments, including the following six new species: Amphicytherura fragilis sp. nov., Brachycythere multidifferentis sp. nov., Fossocytheridea ballentae sp. nov., Fossocytheridea elegans sp. nov., Nigeroloxoconcha itanhaensis sp. nov. and Paracypris eniotmetos sp. nov. 相似文献
18.
平凉安国镇六盘山群介形类 总被引：4，自引：0，他引：4
平凉安国镇六盘山群的介形类化石采自和尚堡组、李洼峡组与马东山组，计１０属２２种（含６新种、１新亚种、３未定种）。自下而上可分为：Ｃｙｐｒｉｄｅａ（Ｕｌｗｅｌｌｉａ）－Ｄａｍｏｎｅｌｌａ组合，时代属中上凡兰吟期；Ｃｙｐｒｉｄｅａ（Ｃｙｐｒｉｄｅａ）－Ｚｉｚｉｐｈｏｃｙｐｒｉｓ组合，时代属豪特里维一巴列姆期及Ｃｙｐｒｉｄｅａ－Ｌｉｕｐａｎｓｈａｎｉａ组合，时代属阿普第期。 相似文献
19.
《Journal of Asian Earth Sciences》2008,31(5-6):629-651
The Bathonian ammonite assemblages have been previously poorly recorded in Kutch. The present study has unearthed a rich array of ammonite taxa ranging from the Middle to Upper Bathonian. While Oxycerites Rollier (1909) is a new record from Kutch, the oldest occurrence of Choffatia Siemiradzki (1898) has been found from the Middle Bathonian horizon. Oxycerites cf. orbis (Giebel) is a zonal index of the Late Bathonian in other areas and thus facilitates interprovincial correlation. Besides, palaeobiogeographic and stratigraphic distribution of many species have been modified based on new information. For example, macrocephalitin species, i.e., Kamptokephalites cf. etheridgei Spath (1928), Macrocephalites bifurcatus transient intermedius Spath (1928), M. cf. mantataranus Boehm (1912) were previously known from West Pacific, Indonesia have been now found in Kutch. Gracilisphinctes Buckman (1920) has been previously known to occur during the Middle Bathonian time, the present work extends its stratigraphic distribution up to the definite Upper Bathonian horizon. Procerites hians (Waagen) an endemic species in Kutch previously known from the Upper Bathonian beds, its stratigraphic range has been extended down to the Middle Bathonian.Detail taxonomy of the newly obtained taxa has been done and in many cases sexual dimorphism has been recognized. 相似文献
20.
A comparative morphological analysis is performed for 13 valid dinocyst species of genus Vesperopsis. Their distribution over Eurasia and North America in the Hauterivian–Cenomanian is traced and the characteristics of these deposits are given. Three species of the most stratigraphically significant dinocysts are distinguished: V. fragilis for the Upper Hauterivian of Western Siberia and V. mayi and V. longicornis for the Aptian of East Greenland. Analysis of facies confinement of the dinocysts Vesperopsis made it possible to group species of the considered genus over conditionally preferable paleosettings. Continental facies (freshwater, brackish-water) are characterized by species V. yanjiensis, V. glabra, V. sanjiensis, and V. jixianensis, while V. zhaodongensiis, V. didaoensis, and V. dolabella are typical of the coastal–marine facies, and V. digitatа, V. nebulosa, and V. mayi are typical of marine facies. 相似文献