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本文研究了广西荔浦上泥盆统榴江组上部扁豆状灰岩中所含的法门期竹节石2属3种,其产出层位分别为牙形刺化石带的 Palmatolepis crepida带和 Pa.marginifera带。 相似文献
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The gastropod fauna of the Upper Devonian Baggy and Pilton formations in south‐west England is revised and includes some 30 taxa. The topmost part of the Upper Famennian succession in Devon is represented by clastic near‐shore and shallow shelf sediments, indicating a short‐term transgressive phase (‘Strunian Transgression’). The sequence yields a highly diverse fauna dominated by brachiopods and ostracodes, locally supplemented by crinoids, bryozoans, trilobites and molluscs. The taxa ‘Patellostium’britannicum sp. nov., Angyomphalus (Angyomphalus) junius sp. nov. and Dictyotomaria eurocapillaria sp. nov. are erected; a junior homonym is replaced by Macrochilina? piltonensis nom. nov. The gastropod fauna displays an independent character, where latest Devonian faunal elements overlap with Late Palaeozoic taxa expressing a transition similar to that of the bivalves, brachiopods, echinoderms and corals, without a sharp faunal break at the Devonian/Carboniferous boundary. Apart from the Caenogastropoda, all subclasses of gastropods are represented. Members of the bellerophontoids, pleurotomarioids and loxonematoids are most abundant, followed by murchisonioids, naticimorphs, euomphalomorphs and platyceratoids. The various gastropod groups represent different ecological demands and trophic categories, and together with the accompanying fauna indicate that nearly all habitats and niches were occupied in the shallow South Laurussian Shelf. 相似文献
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Fossil juvenile coelacanths from the Devonian of South Africa shed light on the order of character acquisition in actinistians 下载免费PDF全文
A new coelacanth genus from the Famennian (Upper Devonian) of South Africa is described, principally from presumed juveniles. S erenichthys kowiensis gen. et sp. nov. uniquely shares with Diplocercides a ventral expansion of the elbow‐like lachrymojugal, as well as a symmetrical diphycercal tail supported by expanded neural and haemal spines and radials. Serenichthys is distinguished from Diplocercides by a number of derived characters, including possession of longer anterior parietals, a more crescent‐shaped postorbital with a more anteriorly positioned infraorbital canal, and a far smaller squamosal, which is well separated from the skull roof. By contrast, Serenichthys appears to lacks a second dorsal fin lobe, a derived feature present in Diplocercides. Most specimens of Serenichthys are between 3 and 6 cm in length. They have large eyes, and dermal bones of the skull ornamented with long wavy ridges, similar to the dermal ornament of other Devonian coelacanths such as Gavinia. Larger isolated operculae also collected from the Waterloo Farm locality and attributed to Serenichthys indicate that with growth the ridges on the dermal bones transformed into elongate tubercles, reminiscent of those of Diplocercides and Carboniferous taxa. Phylogenetic analysis resolves Serenichthys as the sister group of Holopterygius and all known post‐Devonian coelacanths. The clade including the unusual leaf‐shaped coelacanths, the Devonian Holopterygius and Carboniferous Allenypterus, branches from the coelacanth lineage immediately crownward of Serenichthys. The presence of abundant juveniles within an estuarine setting strongly parallels the discovery of similarly sized juveniles of Rhabdoderma exiguus together with eggs and yolk‐sack larvae in the Upper Carboniferous Mazon Creek biota. It is therefore argued that Serenichthys, like Rhabdoderma, was using the sheltered estuarine environment as a nursery. © 2015 The Linnean Society of London 相似文献
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新疆晚奥陶世晚期管状体及其古植物学物意义 总被引:1,自引:1,他引:0
本文系统描述了产自我国新疆塔里木盆地晚奥陶世晚期的管状体,包括2属8种,其中一个新种。通过对比研究,本管状体组合与Burgess和Edwards(1991)的下组合相当。根据本组合的研究,对Burgess和Edwards的组合进行了补充,其组合由不同类型的光壁管、低分异度的内壁加厚管组成、未见外壁加厚管和丝状体,组合的时代从中奥陶世到早志留世(晚Llandovery)。根据植物学的对比研究,管状体主要产自Nematophytales Lang. 相似文献
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Re-interpretation of Wexfordia hookense from the Upper Devonian of Ireland as an arborescent lycophyte 总被引:4,自引:0,他引:4
SHARON D. KLAVINS 《Botanical journal of the Linnean Society. Linnean Society of London》2004,144(3):275-287
New collections of pyritized axes of the lycophyte Wexfordia hookense have been made from the Upper Devonian (uppermost Famennian) type locality at Sandeel Bay, County Wexford, in south-eastern Ireland. The specimens reveal additional histological features that permit reinterpretation of the morphology of this taxon and reevaluation of its taxonomic affinities. Wexfordia is shown to possess both secondary xylem, with narrow, uni- to biseriate rays, and periderm. The range of variation in relative amounts of primary and secondary xylem can be correlated with position in the mature plant. This evidence indicates that Wexfordia was a small tree rather than an herbaceous form. Fine structure of tracheids and additional anatomical features strongly support affinities with Carboniferous arborescent Isoetales, rather than Devonian Protolepidodendrales, and further support the hypothesis that radiation in this lineage was well underway prior to the Carboniferous. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 275–287. 相似文献
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Jean-Georges Casier 《Geobios》1985,18(6):833-855
More than fifty ostracod species, twenty-two of which are Entomozoacea, have been identified in the upper part of the Teferguenite Formation and in the Marhouma Formation. The zonal sequence established on the Entomozoacea is applicable to the Frasnian and the Famennian of the Algerian Sahara; seven zones are recognized. One new species, Tubulibairdia marhoumaensis nov. sp., is described. 相似文献
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Extinction of nanicellid foraminifera during the Frasnian–Famennian biotic crisis: some far‐reaching evolutionary consequences 下载免费PDF全文
Zofia Dubicka 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2018,51(1):112-119
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
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The cuticle of concavicarids (Arthropoda: Thylacocephala) from the early Famennian (Upper Devonian) of the Holy Cross Mountains, Poland was studied with respect to its microstructural details. Investigated laminated cuticle with phosphatic/organic composition, possesses two different kinds of microstructure with assumed sensory functions. The first kind consists of circular depressions, each located in the central area of characteristic polygons forming the carapace exterior ornamentation. These depressions are interpreted as sealed during phosphatisation processes setal lumens. The second kind occurs exclusively in carapace margins. These intracuticular microstructures occur as elongated tubular structures, circular to oval in cross section, penetrating the cuticle interior but not reaching its surface. They form a thin belt with a kind of ‘sensory fields’ on the dorsum and a wider belt in the ventrocaudal part of the carapace. These belts are connected in the rostral and caudal area, forming a continuous sensory zone encompassing each valve. These structures are very similar to crustacean organule canals, and the dorsally situated ‘sensory fields’, suggest some similarity to crustacean sensory dorsal organs. This possible sensory system is the oldest of this kind found in Thylacocephala. Its morphology and presumed canal walls mineralogical composition suggests crustacean affinity of Thylacocephala. 相似文献
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F/F牙形刺灭绝事件以后,牙形刺很快进入复苏期(王成源、Ziegler,2004)。有关法门期牙形刺的辐射,在国内外的文献中还没有详细的论述或论证。本文基于以前对广西桂林垌村和龙门剖面的牙形刺集群灭绝与复苏的研究,2003年又在垌村剖面加密采样,重点是研究F/F事件后,牙形刺由复苏到辐射阶段的特征,探索牙形刺何时和如何由复苏期进化到辐射期。本文的材料主要是依据华南的资料,特别是本文作者研究多年的垌村剖面的资料。牙形刺的灭绝与复苏是以法门期最主要的属Palmatolepis为主线,在种一级的水平上确定的。法门期牙形刺的辐射同样是以Palmatolepis属内种一级的水平上讨论的。同时也涉及到其它属。本文首次明确提出:牙形刺在晚triangularis带就进入辐射期,因为正是从晚triangularis带,Palmatolepis的minuta,werneri,sandbergi,perlobata,cf.regularis,subperlobata,tenupunctata7个重要种群开始出现,并在法门期中期达到辐射期的高峰。 相似文献