首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This study evaluates the severity of the poorly known and mostly underestimated foraminiferal extinction during the Frasnian–Famennian biotic crisis and its evolutionary aftermath. During this global event, worldwide, truly plurilocular planispiral (Nanicellidae) and uniseriate, palmate (Semitextulariidae) foraminifera associated with metazoan reefs died out entirely. Highly advanced test morphology such as that of nanicellids did not reappear in the earth's history until the Late Triassic. Moreover, morphotype comparable to that of the Devonian bilaterally flattened and palmate semitextularids appeared again until the Middle Jurassic (Frondicularia, Lagenida). In terms of the degree of test septation and chamber arrangement as well as general test shape, these foraminifera were ‘very far ahead of their time’. In consequence, foraminifera suffered a significant collapse during the F‐F biodiversity crisis, leading to an amazingly long evolutionary time lag in the case of plurilocular foraminifera lasting at least 150 million years.  相似文献   

2.
An up to 3,000-m-thick pile of Carboniferous rocks covers the northern fringe of the Precambrian Hoggar Massif (Touareg Shield) in southern Algeria, thus terminating the depositional history of the Palaeozoic in this sector of the North African Craton. The previous Devonian (Eifelian to Frasnian) palaeogeographic configuration of the area, characterized by ridges and shallow basins, is leveled by a widespread Famennian playa and lower Tournaisian delta sedimentation on a largely undifferentiated shelf. Tournaisian to Moscovian strata were deposited under open-marine, deltaic, shallow-subtidal, fluvial, and continental environments. The Carboniferous sequence can be subdivided into 12, largely interfingering, lithostratigraphic formations, which were dated by conodonts, ammonoids, foraminifers, and brachiopods, yielding a modified biostratigraphic framework of the area. The formations are stacked in four transgressive–regressive cycles, which include two major gaps, one during the middle Tournaisian, the other during the middle Visean to Serpukhovian. The oscillations of sea level can be traced into neighboring areas and seem coeval to early pulses of the Late Carboniferous/Early Permian glaciation of Gondwana. To a lesser degree they may reflect more local tectonic effects of the Variscan orogeny.  相似文献   

3.
Stratigraphic sections and microfossils samples from the upper part of the “Graptolitic Shales-Orthoceras Limestones” and from the Camprodon Formation lying in the area of Camprodon, eastern Pyrenees, Spain, have been studied. Some beds at the top of the “Graptolitic Shales-Orthoceras Limestones” correspond to the Torres Member of the Rueda Formation, and conodont faunas, indicating a Lochkovian age, are described. The Camprodon Fm. is interpreted to be turbidites deposited in deep sea fans, although slope deposits prevail in the eastern sections. One reworked carbonate clast from the Camprodon Fm. provided a valuable early Ludlow conodont fauna, from the Kockelella crassa Zone, reported for the first time in the Iberian Peninsula. Late Devonian conodonts and late Visean (Asbian-Brigantian) foraminifers and algae were also obtained from reworked limestone clasts, and latest Visean or Serpukhovian foraminifers from the sandstone matrix in the Camprodon Fm. The studied microfossils suggest a late Mississippian age for the Camprodon Fm. instead of the previously assigned late Silurian-Lochkovian age. This age must be considered when discussing the distribution of the Culm Facies in the Pyrenees and the significance of the contact between the Camprodon Fm. and the underlying “Graptolitic Shales”.  相似文献   

4.
Microfacies analyses performed on the latest Permian Wujiaping Formation at Laren (Guangxi Province, South China) show that the bioclastic-rich limestones of Late Permian age contain a rich and well-diversified foraminiferal fauna. This fauna is here revised in order to be compared with time-equivalent levels of southern Iran and southern Turkey. Some new and unexpected phylogenetic trends are highlighted among the biseriamminoids. The new or poorly known genera Retroseptellina, Septoglobivalvulina, Paraglobivalvulinoides, Dagmarita?, Bidagmarita nov. gen., Louisettita, Paradagmaritopsis nov. gen. and Paradagmarita? are concerned. Nevertheless, these newly appeared biseriamminoids are subordinate to abundant Tetrataxis and Climacammina, ultimate survivors of the families Palaeotextulariidae and Tetrataxidae, appeared as old as the Early Carboniferous (“Mississippian”). Algae, miliolids, and nodosarioids are poorly represented. Two genera and four species are here newly described: Globivalvulina curiosa nov. sp., Louisettita ultima nov. sp., Bidagmarita nov. gen., Bidagmarita sinica nov. gen. nov. sp., Paradagmaritopsis nov. gen., Paradagmaritopsis kobayashii nov. gen. nov. sp. The palaeogeographic distribution of these foraminifers is interpreted to be typically of Neo-Tethyan regions, ranging from southern Turkey (Hazro) to South China (Laren) and up to Japan for some species (i.e., Paradagmaritopsis). At Laren, Late Permian strata are generally characterized by Reichelina ex gr. simplex Sheng. Isolated samples of packstones, collected in Tsoteng region (Guangxi Province, South China), contain Sphaerulina sp. together with various smaller foraminifers and numerous representatives of the new species G. curiosa nov. sp. In this study we demonstrate that the regions of Zagros (Iran), Taurus (Turkey), South China and even Japan shared similar foraminiferal assemblages and represented intermittently connected palaeobiogeographic provinces during Late Permian times.  相似文献   

5.
The origin and early diversification of decapod crustaceans and their expansion from marine to continental environments are key events in arthropod evolution. Rare fossil decapods are known from the Palaeozoic, and the earliest eumalacostracans with undoubted decapod affinities are the Late Devonian Palaeopalaemon and Aciculopoda, found in offshore marine deposits. Here, we describe a new species of the shrimp Tealliocaris found in floodplain and temporary pond deposits from the Famennian (Late Devonian) of Belgium, together with a rare Palaeozoic assemblage of other crustaceans (conchostracans, notostracans and anostracans) and chelicerates (eurypterids). Tealliocaris walloniensis sp. nov. documents the earliest occurrence of continental decapod crustaceans and indicates that decapods have been part of continental ecosystems at least since the Late Devonian.  相似文献   

6.
《Comptes Rendus Palevol》2002,1(6):471-477
Frances L. Parker made important contributions to the knowledge of benthic and planktonic Foraminifera, both in respect to taxonomy and to biogeographic and stratigraphic distributions. Her work became part of the foundations of modern paleoceanography, which may be said to begin with the results of the Swedish Deep-Sea Expedition (R/V Alabatross, 1947–1948). Among her most significant works is a demonstration of warm-cold cycles in the Mediterranean, based on Albatross cores, a reorganization of the classification of recent planktonic foraminifers, and a study of lineages in planktonic foraminifers for the Late Cenozoic.  相似文献   

7.
Summary Carbonate-dominated successions of the Gipsdalen and Tempelfjorden Groups from Svalbard record a significant shift from Photozoan to Heterozoan particle associations in neritic settings during the late Palaeozoic. During the Bashkirian, benthic particle associations which included photoautotrophs such as phylloid algae (Chloroforam Association) characterised shallow subtidal environments. Most depositional settings which endured siliciclastic terrestrial input exhibited poorly diversified associations dominated by brachiopods, bryozoans and siliceous sponges (Bryonoderm Association). During the Moscovian to Asselian, highly diversified associations typified by various calcareous green algae,Palaeoaplysina, Tubiphytes, fusulinids, smaller and encrusting foraminifers (Chloroforam Association) prevailed in carbonate sediments from supratidal to shallow subtidal environments. During the Sakmarian and Early Artinskian, oolitic carbonate sands (Chloroforam Association) typified intertidal flats, whereas shallow subtidal environments were occupied by moderately diversified associations with fusulinids, smaller foraminifers, echinoderms and bryozoans (Bryonoderm-extended Association) and poorly diversified associations with echinoderms, brachiopods and bryozoans (Bryonoderm Association). During the Late Artinskian to Kazanian, poorly diversified associations characterised by brachiopods, echinoderms and bryozoans (Bryonoderm Association), and sponge-dominated associations (Hyalosponge Association) reigned within siliceous carbonates of intertidal and shallow subtidal environments. This trend is interpreted as a result of climatic cooling and fluctuations of prevailing levels of trophic resources within shallow-water settings during the studied time period. While raised nutrient levels were restricted to near-shore settings during the Bashkirian, steady mesotrophic conditions arose from the Sakmarian onward and increased to late Permian times.  相似文献   

8.
In South Tunisia, the Bir Mastoura (BMT-1) borehole provides Carboniferous, Permian, and early Triassic foraminifers and carbonate algae which permit to establish a local biozonation which can be correlated with (1) the Capitanian (Late Middle Permian) outcrops of Jbel Tebaga; (2) other Tunisian boreholes; and (3) several stratotypes and/or well-studied Tethyan outcrops. Microfacies, microfaunas and microfloras of BTM-1 reveal subtropical, carbonate, inner platform deposits. As everywhere in the world, the Early Triassic is faunistically very poor. The Upper Permian and Upper Middle Permian microfaunas and microfloras are traditional in Tunisia, but a little poorer than the Tebaga assemblages. The fusulinids of the middle and lower Middle Permian strata are also less numerous than in other Tunisian boreholes. The late Pennsylvanian fusulinids known in some of these boreholes, were not observed in BMT-1; however, these fusulinids are re-discussed here due to their biostratigraphic and palaeobiogeographic importance; they are assigned to two substages, early Gzhelian with Darvasoschwagerina spp. and late Kasimovian with Schwageriniformis petchoricus. Neither early-middle Kasimovian nor late Moscovian microfossils were found, and their absence is probably regional in the whole North Africa. In contrast, the early Moscovian beds yield all the fusulinid biozones of the Urals (Russia) and display diversified microfauna with Profusulinella aff. simplex, Ovatella ex gr. ovata; Depratina timanica, Aljutovella (Tikhonovichella) rhombiformis, Hemifusulina spp., Eofusulina aff. tashlensis, Paraeofusulina trianguliformis, Moellerites cf. praecolaniae and Parabeedeina cf. pseudoelegans. The middle-late Bashkirian seems to be only partially represented, whereas the early Bashkirian is similarly relatively complete, with Varvariella ex gr. varvariensis, Plectostaffella cf. karsaklensis, P.? nauvalia, Semistaffella? sp. and common oolitic microfacies. The Serpukhovian and late Visean appear more developed than in other boreholes. They yield Praedonezella, Eosigmoilina and Endostaffella. As across the North Africa, no older Mississippian foraminifers are not known prior to the late Visean. The palaeogeography is discussed thanks to the regional new data; especially the concept of a Saharan province, or its replacement by multiple aborted rifts during the late Visean-Serpukhovian. From the Bashkirian to Early Permian, affinities with Croatia are frequent. Comparisons with other North African basins, northern Spain, Donets Basin, the Urals basins, Moscow Basin, Taurus and Alborz are also presented.  相似文献   

9.
Liverworts are generally regarded as rare elements in Palaeozoic floral assemblages. However, a focus on dark gray to black shales and siltstones in the Middle–Late Devonian Catskill Delta of eastern New York shows that liverworts are locally quite common as well-preserved, apparently parautochthonous specimens in thin, lenticular, dark gray–black shale and siltstone lenses. These lenses are either dysoxic–anoxic lacustrine or estuarine facies deposited under oxygen-stratified water masses or rapidly deposited flood plain deposits that were not oxidized after deposition. Carbonized remains of the upper Middle Devonian (Givetian) liverwort Metzgeriothallus sharonae sp. nov. are locally common in these lenses. Well-preserved thalli (gametophytes) are only evident by projecting polarized light on the shale and siltstone surfaces. An associated sporophyte capsule is the first evidence of a reproductive structure in a Devonian liverwort. Metzgeriothallus sharonae sp. nov. is the oldest known liverwort. The age of the new species helps recalibrate chloroplast DNA studies that have led to proposals of the timing of liverwort diversification by showing that the evolutionary separations of the Jungermanniopsida and Marchantiopsida and of the Metzgeriidae and Jungermanniidae [previously thought to be Late Devonian and Late Carboniferous, respectively] were no younger than late Middle Devonian.  相似文献   

10.
In a revision of previously published materials, two new spiriferid species from the Late Tournaisian, Unispirifer subtornacensis sp. nov. and Mesochorispira ussuilensis sp. nov., and Atylephorus nalivkini sp. nov. from the Lytva Horizon of the Upper Devonian of Bashkiria are described. Based on the original collection, a new Serpukhovian subspecies, Podtsheremia duplicicosta triplicicosta, from the southern Ural Mountains and a new Late Carboniferous species, Purdonella kalashnikovi, from the polar Ural Mountains and adjacent islands are established.  相似文献   

11.
New finds of Late Palaeozoic arachnids, based on three well-preserved carapaces from the Carboniferous of Russia and Ukraine and one complete, albeit poorly preserved, specimen from the Permian of Kazakhstan, are described. The spider genus Arthrolycosa is reported from the Late Carboniferous (Late Pennsylvanian: Kasimovian–Gzhelian) of Chunya in the Tunguska Basin of Siberia; it is the first find of a spider outside the Carboniferous tropics. Another fossil assigned to the same genus comes from the Late Carboniferous (Early Pennsylvanian: Bashkirian) of Kamensk–Shakhtinsky in the Donets Basin of Russia; it is probably the oldest fossil spider known. A thelyphonid (whip scorpion) carapace is described from the Late Carboniferous (Late Pennsylvanian: Kasimovian) of the adjacent Lugansk Province of the Donets Basin of Ukraine.  相似文献   

12.
From the later part of the Devonian through the Permian, calcareous foraminifers became abundant and evolved rapidly. This rapid evolution of taxa forms the basis of a detailed zonation through the Carboniferous and Permian. Comparison of this evolutionary history of foraminifers, their biostratigraphic zonation, and the depositional sequences in which they occur suggests that sea-level events in late Paleozoic depositional history contributed significantly in subdividing a fairly continuous evolutionary record into a succession of about 75 identifiable foraminiferal zones during a 100–125 Myr time span. Although variable in terms of duration and vertical occurrences, the more completely recorded high-stand intervals give brief histories of the foraminiferal evolutionary record and are sandwiched between the poorly recorded or unrecorded low-stand intervals. Many of the individual foraminiferal zones are confined to a single depositional sequence.The late Paleozoic carbonate foraminiferal fossil record, as with the rest of the fossil record, is strongly affected by sediment deposition-nondeposition as a result of major changes in sea level. This incomplete fossil record is the result of repeated depositional breaks because of the way that depositional sequences form. It is not possible to ascribe macromutations, ‘punctuated’ evolution or ‘punctuated gradualism’ as the cause of this evolutionary pattern of the shelf-carbonate fossil record. This pattern is distinctive and we refer to it as ‘sequence evolution’ and ‘sequence extinction’. In the later part of the Middle Permian and in the Late Permian, the fossil record clearly illustrates that a series of faunal losses through ‘sequence extinctions’ progressively exceeded faunal replacements and new species through ‘sequence evolution’, but not a ‘mass extinction’ as is commonly ascribed to the end of the Permian Period. Most Permian faunas became extinct in the interval of 8 to 4 million years before the end of the Late Permian.  相似文献   

13.
《Palaeoworld》2020,29(2):270-302
This paper aims to evaluate potential biostratigraphic markers for the Viséan–Serpukhovian boundary in sections of Europe and Asia, to help identify the base of the global Serpukhovian Stage, which is a high priority task for Carboniferous biostratigraphy. Sections in the Serpukhovian stratotype area in the Moscow Basin contain a gap at the base of the Tarusian Regional Substage (basal in the classical Serpukhovian), so the traditional boundary defined in these sections cannot be precisely correlated with other successions worldwide. The IUGS Task Group to establish a GSSP close to the traditional Viséan–Serpukhovian boundary focused on the search for a new boundary marker, primarily on the first appearance datum (FAD) of the conodont Lochriea ziegleri in the lineage Lochriea nodosa to Lochriea ziegleri, considering it to be a suitable biostratigraphic event. The FOD (first occurrence datum) of L. ziegleri has been recognized in many successions worldwide, although only in a few sections the supposed evolutionary lineage of L. ziegleri was inferred. There are serious impediments to the FAD of L. ziegleri being universally accepted as the boundary marker. This paper presents a review of the FOD levels of L. ziegleri documented so far from multiple sections along with other correlatable markers (foraminifers and ammonoids) that can serve as additional points of reference in sections where a conodont record is poor or absent. The reviewed sections are Naqing Section (South China), Verkhnyaya Kardailovka and Kugarchi sections (South Urals, Russia), Mariinsky Log and Ladeinaya Mountain Sections (western slope of the Middle Urals, Russia), Novogurovsky Section (Moscow Basin, Russia), Vegas de Sotres Section (Cantabrian Mountains, Spain), Lugasnaghta Section (County Leitrim, Ireland), Wenne River Bank Section (Germany), and Milivojevića Kamenjar Section (Družetić, NW Serbia). We also included a compilation of data from sections of North England and southern Scotland. In this paper, we will mainly focus on newly described sections, while the discussion of most previously described sections was summarized by Nikolaeva et al. (2001, 2002, 2005, 2009b) and other publications, so they are only briefly mentioned in this review. It should be added that there is no such a thing as a perfect GSSP section, as each section has certain disadvantages, either lithological, paleontological, or both, so it is important to hear and discuss all the different opinions to develop the optimum strategy for future research. In addition, we analyze published records from several sites in North England and southern Scotland. We discuss the first appearances of the ammonoid genera Cravenoceras, Edmooroceras, Lyrogoniatites, Dombarites, and Platygoniatites, the foraminifers Neoarchaediscus postrugosus, Hemidiscopsis muradymica, H. hemisphaerica, species of Janischewskina and Monotaxinoides, Eostaffella pseudostruvei group, Eostaffellina decurta, and Endothyranopsis plana. We publish here for the first time the useful accounts of foraminifers and conodonts from the Mariinsky Log Section and Ladeinaya Mountain Section (Middle Urals, Russia), and re-figure several important type specimens from Europe and the Urals.  相似文献   

14.
《Comptes Rendus Palevol》2014,13(7):545-554
The position of Palaeozoic and Mesozoic roachoids and their relationships to crown-group Dictyoptera is an unresolved problem of insect systematics since Hennig's time. This contribution presents new data based on the wing venation of the Early Cretaceous group Cratovitismioidea (so-called “Umenocoleoidea”) supplemented with the discovery of the first Late Palaeozoic representative. As Umenocoleus, type genus of the Umenocoleidae, is considered as a Coleopterida, the roachoids currently included in the Umenocoleidae are transferred to the new family Ponopterixidae, in the new superfamily Cratovitismioidea. Permoponopterix lodevensis, a new ponopterixid genus and species, is described as the oldest representative of this superfamily, from the Middle Permian of the South of France. A new species Ponopterix burkhardi is described from the Lower Cretaceous of Crato Formation in Brazil. Convergent adaptations of tegmina in Coleopterida, Protelytroptera and Cratovitismioidea are discussed.  相似文献   

15.
Wetland forests, known as coal forests, extended over large areas of the palaeotropics during the Late Carboniferous and the Permian Periods. They were initiated during the Serpukhovian Age as a response to lowering sea levels having exposed large areas of continental shelf. They expanded dramatically during the late Bashkirian Age, but then contracted by over one‐half during the Kasimovian Age. The estimated loss of carbon sink probably resulted in an annual increase in atmospheric CO2 of about 2–5 ppm, and coincided with clear evidence of global warming in both the northern and southern high latitudes. A return to cooler conditions in very Early Permian times coincided with an expansion of the palaeotropical coal forests in the Far East, but this was short‐lived and most of the rest of the Permian was a time of global warming. The Palaeozoic evidence clearly confirms that there is a correlation between levels of atmospheric CO2 and global climates. However, care must be taken in extrapolating this evidence to the present‐day tropical forests, which do not act as a comparable unsaturated carbon sink.  相似文献   

16.
Post-lower Serpukhovian conglomerates with abundant limestone clasts are intercalated within the Carboniferous flysch succession of the Ghomarides (internal zone of the Rif, northern Morocco). They are restricted to two ghomaridic nappes (Beni Hozmar, Akaili; Fig. 1). No limestone-bearing conglomerates are known from the third nappe (Kuhdiat Tizian). 83.4% of the limestone clasts derived from shallow-shelf environments and adjoining proximal slope environments of late Viséan (V3b gamma) to early Serpukhovian (Namurian E1–E2) age. Microfacies types of the inner shelf lagoon and of restricted shelf environments dominate. They indicate a complicated mosaic facies pattern (Fig. 2). 16.6% of the limestone clasts derived from distal slope environments and deep, open marine environments. They are of unknown age except for one Upper Devonian pebble from around the transition do IIα/do IIβ. All are supposedly of late Middle Devonian and Late Devonian age. Their sedimentology as well as the age and the microfacies of the limestone clasts indicate that the conglomerates of the Ghomarides are homologous to the Marbella Formation of the Malaguides (Betic Cordillera, Southern Spain). The conglomerate of Binifaillet (Minorca, Balearic Islands) is also similar. The source area of the conglomerates was the not any more existent Betico-Rifean Block south of the Malaguide-Ghomaride flysch trough. Owing to their facies development in Devonian and Carboniferous times, the nappes of the Ghomarides and the Malaguides can be arranged in a successively more distal position towards the source: nappe of Beni Hozmar—nappe of Kuhdiat Tizian—nappe of Akaili + Malaguides (Fig. 4). Minorca, which received its flysch sediments from the north, seems to be influenced only episodically by conglomerate inputs from the south. The lithofacies development of the Carboniferous in other Paleozoic massifs of the western Mediterranean clearly demonstrates that the Paleotethys of this region was framed by shallow-water carbonate shelves between early Viséan and Moscovian times. These shelves are not preserved in situ, but gravitative carbonate sediments, conglomerates, slide blocks and gravitational nappes with in the flysch troughs confirm their existence. The flysch troughs were situated at active continental margins. They developed initially in the northern Paleotethys realm (southern border of the Southern European plate) starting with the late Viséan; in the southern Paleotethys realm (northern border of the Betico-Rif block) they started in the lowermost Viséan. The appearance of the flysch troughs records the beginning subduction of the Paleotethys towards the north beneath the Southern European plate as well as towards the south beneath the Betico-Rifean block (Fig. 6). Flysch sedimentation was predated by pelagic sedimentation since the earliest Carboniferous. During the Viséan a successive deepening of the western Mediterranean Paleotethys from north to south was recorded in the facies development of the pelagic deposits. The deepening is genetically connected with the earlier start of the subduction at the Betico-Rifean block.  相似文献   

17.
A complete Devonian sequence is well exposed in the eastern Taurides, forming more than 1000 m-thick succession of carbonate and siliciclastic sediments. The carbonate succession, stratigraphically ranging from Middle Devonian to early Late Devonian and mostly comprising limestones, dolomitic limestones and reefal limestones, contains abundant and diverse assemblages of foraminifers, corals, stromatoporoids, calcareous algae, bivalves, brachiopods, ostracods, and conodonts. The limestone samples collected from a more closely sampled stratigraphic section have been investigated for their foraminiferal content. The micropalaeontological analyses carried out on these samples have revealed the presence of an early Frasnian foraminiferal assemblage including predominantly unilocular parathuramminid species and multilocular forms of the genera Nanicella, Paratikhinella and Semitextularia? and further indicated the presence of a new genus and a new species Halevikia deveciae n. gen. n. sp. which appears as an important phylogenetic and stratigraphic transitional taxon between the families Baituganellidae n. fam. and Tournayellinidae, the phylogenetic potentiality of which during the Late Devonian is currently probably underestimated.  相似文献   

18.
The taxonomic revision of the carbonate microbiota of the limestone lenses intercalated into the Carboniferous siliciclastic series of Balia-Maden (Turkey) shows that most lenses are early or middle Brigantian in age (latest Visean), only a single lens being of younger age (late Serpukhovian). Calcareous microbiota are abundant in the Balia-Maden lenses carbonates. Microfacies analysis shows the dominance of shallow water environments. The Brigantian assemblage is accurately illustrated. The new foraminiferal taxon Cribrospira baliamadeni nov. sp. is morphologically similar to type-material of Cribrospira panderi von Möller, but has a porous wall with wider pores, almost keriothecal. C. baliamadeni nov. sp. corresponds to the misinterpreted Bradyina and Janischewskina of the previous literature on Balia-Maden lenses. These limestones show a great diversity of algosponges (carbonate microproblematica). Among them, (1) small, atypical Fasciella previously confused with Eosigmoilina; (2) an abundant form described for the first time, Frustulata reticulata nov. sp.; and (3) typical Falsocalcifolium punctatum (Maslov), important for the biostratigraphic implications, are also mentioned. The single Serpukhovian lens consists of a grainstone and contains the age-sensitive alga Archaeolithophyllum johnsoni Racz, and the foraminifers Monotaxinoides gracilis and Janischewskina sp.  相似文献   

19.
《Palaeoworld》2022,31(3):402-418
Sphenophyllum Brongniart constitutes a common and important element in the Carboniferous and Permian floras around the world, but its records in the Devonian Period are limited and remain to be investigated with respect to their morphology, anatomy, and distribution. Diversity of Sphenophyllum during Late Devonian in South China was significant with the presence of the well-known species including S. lungtanense Gothan and Sze, S. pseudotenerrimum Sze, and S. changxingense Huang et al. In this article, we describe a new species of the genus, S. fanwanense n. sp., from the Fanwan section of Changxing County, Zhejiang Province, characterized by having at least two orders of axes, with six spoon-shaped leaves attached at the node. A comprehensive review of previous records of Sphenophyllum from the Upper Devonian of South China shows that at least four species (S. fanwanense, S. lungtanense, S. pseudotenerrimum and S. changxingense), each with distinct leaf morphology, occur in South China in the Late Devonian, mostly from the Wutong Formation (Famennian). Given the lack of concrete evidence for anisophylly or heterophylly among the Devonian Sphenophyllum species (and more broadly, the Devonian sphenopsids), we suggest that the development of these features later in the Carboniferous and Permian periods was likely related to an increase in complexity of forest communities through time.  相似文献   

20.
The Middle-to-Upper Permian in the Kuh-e Gakhum anticline (southeastern Iran) has rarely been studied due to its structural complexity and the difficult access. Rich Permian fusulinid assemblages varying in age from Wordian to Changhsingian were found in a thick carbonate succession corresponding to the Dalan Formation. Three new species of foraminifers are described and a new biostratigraphic framework including five biozones is proposed. One of these, described and defined for the first time in the Dalan Formation, is based on the presence of Praedunbarula simplicissima n. gen. n. sp. When compared to the fossil content of existing bioprovinces, the floro-faunal biota of the Dalan Formation shows an affinity with Central and Western Tethys. A mass extinction of fusulinids and small foraminifers (70%) occurred concomitantly with the onset of a relative sea-level fall. This event led to a change in the carbonate factories from biologically induced carbonate production to ooid-rich chemically induced precipitation. The morphology of the platform at the Guadalupian/Lopingian transition evolves from a bioclastic ramp to a shelf. This transition is also characterized by a major sequence boundary and morphological anomalies in foraminifers. Therefore, as the regression and the changes in floro-faunal contents have been observed at the Guadalupian/Lopingian boundary, the extinction event is considered as end-Guadalupian. It is followed by a Lopingian transgression yielding renewed foraminiferal assemblages.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号