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1.
Ji Li-ming 《植物学报(英文版)》1995,37(7)
Plenty of sporo-pollen fossils were found from the Upper Subformation of Hekou Formation at Chaijiatai, Lanzhou of Gansu, Minhe Basin. The sporo-pollen assemblage of the upper stratum of the Upper Suhformation was named as Schizaeoisporites-Cicatricosisporites. It could be further divided into two subassemblages. The upper one was Classopollis-Schiza- eoisporites, and the lower one was Piceapollenites-Cicatricosisporites. By analysing the periods of the important species and genera in the assemblage and comparing with the known assemblages in various districts, the author cosidered that the geologic age of the assemblage was the late phase of Early Cretaceous (Aptian-Alhian). The age of the second subassemblage was later which was Albian. So far, the stratum where the sporo-pollen fossils assemblage were found was the uppermost one of the Lower Cretaceous that have been found in Minhe Basin. 相似文献
2.
Wang Yong-dong 《植物学报(英文版)》1995,37(12)
About 98 species of fossil spores and pollen referred to 55 genera from the Upper Carboniferous Yanghugou Formation in Zhongwei, Ningxia have been studied. Two sporopollen assemblage zones are recognized in ascending order as follows: 1. Laevigatosporites medius-Cyclogranisporites aureus (MA) zone: This assemblage corresponds to the lower part of the Yanghugou Formation, and is characterized by the predominance of pteridophyfic spores and the relative abundance of gymnospermous pollen. Azonotriletes and monoletes are dominant, while zonates are of importance. The most common species are Leiotriletes spp., Cyclogranisporites aureus Potoni6 et Kremp, Granulatisporites granulatus Ibrahim, Microreticulatisporites concavus Butterworth et Williams, M. nobilis (Welcher) Knox, Triquitrites bransonii Wilson et Hoffmeister, Dictyotriletes bireticulatus (Ibrahim) Smith et Butterworth, Ahrensisporites guerickei (Horst) Potonie et Kremp, Lycospora spp., Crassispora kosankei (Potonie et Kremp) Bharadwaj, Cirratriradites saturni (Ibrahim) Schopf, Wilson et Bentall, Laevigatosporites spp., Columinisporites ovalis Peppers, Florinites junior Potnie et Kremp and Vesicaspora wilsonii (Schemel) Wilson et Venkatachata. This assemblage is comparable with those of the Yanghugou Formation in Baiyantaohai of Inner Mongolia (Yu, 1983), the 8th zone of North China by Gao (1979), the Triquitrites sinani-Cirratriradites saturni (SS) Zone and the Microreticulatisporites nobilis-Florinites junior (NJ) Zone of West Europe, which are considered corresponding to Westphatian A-B in age. 2. Torispora seuris-Punctatisporites hians (SH) zone: This assemblage is equivalent to the upper part of the Yanghugou Formation, and is also characterized by dominance of pteridophytic spores and subdominance of gymospermous pollen. In addition to the most commen species mentioned above, the important taxas in the present assemblage comprise Punctatisporites hians Wang, Gulisporites cochlearius Imgrund, Verrucosisporites kaipingiensis Imgrund, Endosporites globiformis (Ibrahim) Schopf, Wilson et Bentall, Densosporites anulatus (Loose) Smith et Butterworth, D. reticuloides Ouyang et Li, Simozonotriletes labellatus Wang, Torispora securis Balme, Thymospora thiessenii (Kosanke) Wilson et Venkatachala, Pit yos porites west phalensis Williams and Plat ysaccus, Illinites, C ycadopites, etc. This zone compares closely with those of the upper part of the Yanghugou Formation in Hengshanbu (Wang Hui, 1984) and Ordos Basin (Geng, 1985), the Benxi Formation in Shanxi (Liao, 1987; Ouyang and Li, 1980; Gao, 1979), as welll as Torispora securis-T, laevigata (SL) Zone and Thymospora obscura-T, thiessenii (OT) Zone of West Europe. Therefore, the present SH Zone should be referred to Westphalian C-D in age. The Westphalian palynofiora in Zhongwei is dominated by Filicopsida and pteridospermopsida; Sphenopsida and lycopsida occupy the subdominant position, while Cordaitopsida and Coniferopsida do not develop well. This palynofiora indicates a tropical-subtropical warm and humid paleoclimate. 相似文献
3.
报道了新疆吐鲁番拗陷北部勒1、米1 、山1和墩1井中侏罗世孢粉化石52属81种.建立了本区中侏罗世孢粉组合: Cyathidites-Psophosphaera-Cycadopite 组合、 Cyathidites-Quadraeculina-Classopollis 组合和 Cyathidites-Callialasporites-Classopollis 组合.它们分别产自西山窑组、三间房组和七克台组.根据孢粉组合特征及其对比, 认为3个组合的地质时代属阿林-巴通期.经研究表明, 中侏罗世早期的植被是以银杏、苏铁类和松柏类等乔木为主体, 并伴有桫椤科树蕨及紫萁科和卷柏科等草本植物.古气候应属温暖潮湿的亚热带气候.至中侏罗世中晚期, 掌鳞杉科植物在植被中占主导地位, 指示当时的气候趋于干旱. 相似文献
4.
报道了新疆吐鲁番拗陷北部勒1、米1、山1和墩1井中侏罗世孢粉化石52属81种。建立了本区中侏罗世孢粉组合:Cyathidites-Psophyosphaera-Cycadopite组合、Cyathidites-Quadraeculina-Classopollis组合和Cyathidites-Callialas-porites-Classopollis组合。它们分别产自西山窑组、三间房组和七克台组。根据孢粉组合特征及其对比,认为3个组合的地质时代属阿林-巴通期。经研究表明,中侏罗世早期的植被是以银杏、苏铁类和松柏类等乔木为主体,并伴有桫椤科树蕨及紫萁科和卷柏科等草本植物。古气候应属温暖潮湿的亚热带气候。至中侏罗世中晚期,掌鳞杉科植物在植被中占主导地位,指示当时的气候趋于干旱。 相似文献
5.
The Middle Jurassic palynoflora from the two wells of PUl and CN1 of Turpan-Shanshan area in Xinjiang consists of 97 species of fossil spores and pollen grains referred to 45 genera, of which 2 species are newly described. Three palynological assemblages including: 1) Cyathidites-Cycadopites-Quadraeculina (CCQ), 2) Cyathidites-Classopollis-Picites (CCP) and 3 ) Granu-latisporites-Classopollis-Podocarpidites (GCP) assemblages are established in the Xishanyao, Sanjianfang and Qiketai Formations, respectively. Comparisons have been made between these assemblages with those of the adjacent regions in Xinjiang and other domestic areas and at abroad. The geological age of the CCQ assemblage is suggested to be at early Middle Jurassic (corresponding to Aalenian to Bajocian age); while the CCP and GCP assemblages are considered to be at late Middle Jurassic (corresponding to early to late Bathonian age, respectively). 相似文献
6.
Twenty-eight species (or forms) of fossil pollen and spores referred to 20 genera extracted from the crude oil samples collected from the Kuche Seg of the Talimu Basin in Xinjiang are observed. The conception of the petroleum sporopouen assemblage is further expounded and the classification of the petroleum sporo-pollen assemblage is also tentatively proposed. According to the characteristics of the assemblages, the problem on oil source of the mentioned oil-bearing region is discussed in this paper. The petroleum sporo-pollen assemblage of Jurassic reservoir of Kucbe Seg is composed of Deltoidospora perpusilla, D. gradata, Cyathidites minor, Hymenophyllumsporites deltoidus, Cingulatisporites problematicus, Cibotiumspora paradoxa, Osmundacidites ap., Cycadopites typicus, C. nitidus, Podocarpidites multesimus, Alisporites grandis, Alisporites bilateralis, Parvisaccites sp., Abietineaepollenites microalatus, A. minimus, PinuspoRenites sp., Piceaepollenites sp., etc. These species of spores and pollen have been found from the Jurassic deposits in this region or in the adjacent regions. The petroleum sporo-pollen assemblage only contains the spores and pollen which coincide with those of the reservoir in age. There is not any spore or pollen older or younger than the reservoir. Consequently, it may be referred to a monotonous type of petroleum sporo-pollen assemblage. The petroleum sporo-pollen assemblage of Cretaceous reservoir of this region consists of Deltoidospora perpusilla, Cryathidites minor, Cibotiumspora paradoxa, Schizaeoisporites zizyphinus, Osmundacidites sp., Crcadopites typicus, C. nitidus, Parvisaccites sp., Cedripites cretaceus, Abietineaepollenites microalatus, A. minimus, Pinuspollenites sp., etc. All these species distribute either in the Jurassic deposits or in the Cretaceous deposits in this region or in the adjacent regions. The distribution of Schizaeoisporites zizyphinus and Cedripites cretaceus is usually limited to the Cretaceous deposits. Both the Cretaceous species and the Jurassic species are comprised in the assemblage, so it may be referred to a composite type of petroleum sporo-pollen assemblage. The petroleum sporo-pollen assemblage of Tertiary reservoir comprises Deltoidospora perpusilla, Cyathidites minor, Cibotiumspora paradoxa, Schizaeoisporites zizyphinus, Poly-podiaceaesporites sp., Cycadopites nitidus, Podocarpidites multesimus, Parvisaccites sp., Abietineaepollenites mininus, Pinuspollenites labdacus, Piceaepollenites alatus, Cedripites ovatus, Ephedripites fusiformis, Quercoidites microhenrici, Chenopodipollis multiporatus, C. microporatus, Artemisiaepollenites sdlularis, etc. Besides the Tertiary pollen and spores, the assemblage contains the Jurassic species and the Cretaceous species, and therefore it belongs to a composite type of petroleum sporo-pollen assemblage. The monotonous type of petroleum sporo-pollen assemblage reflects that the oil source rock is coincident with the reservoir rock in age, and the composite type of petroleum sporopollen assemblage shows that the oil source rock is generally older than the reservoir rock. Based on the investigation of the petroleum sporo-pollen assemblages, the oil source rock of the Kuche Seg is considered to be Jurassic Period in age, and the Lower Jurassic Yangxia Formation and the Middle Jurassic Kuzilenuer Formation are considered to be favorable source rock. The conclusion is supported by the result of the organic geochemical investigation. 相似文献
7.
内蒙古东胜中侏罗世延安组孢粉组合 总被引:2,自引:0,他引:2
研究了内蒙古东胜罕台川、碾盘梁沟和柳沟 3个剖面中侏罗世孢子花粉化石 34属 6 3种 ,包括 2个新种。基于 10个样品中发现的 386 3粒孢子花粉化石的鉴定和统计 ,建立东胜地区延安组孢粉组合。该组合中蕨类植物孢子有 19属 37种 ,含量占 46 %~ 49% ,最低为 39%。裸子植物花粉略占优势 ,有 15属 2 6种 ,含量为 5 1%~ 5 4% ,最高达 6 1%。与国内外相关资料对比结果表明该孢粉组合的地质时代应属中侏罗世巴柔期。孢粉植物群反映研究区在中侏罗世早期为暖温带或亚热带的暖湿气候 相似文献
8.
《Geobios》2020
Pelliales is a basal lineage of the simple thalloid liverworts. Here, we describe a simple thalloid liverwort from the Middle Jurassic Xishanyao Formation of the Turpan–Hami Basin, Xinjiang Uygur Autonomous Region in northwestern China. The thalloid fossil liverwort is described as a new species: Pellites hamiensis (Pelliaceae, Pelliales). Pellites hamiensis nov. sp. resembles the extant species of Pelliaceae in having ribbon-like segments, conspicuous costae that appear as ridges on the ventral surface, rectangular cells with thickened walls adjacent to the margin, and elongated cells in the middle part of the thallus. The occurrence of P. hamiensis nov. sp. extends the fossil records of Pellites back to the Aalenian-Bajocian or Bajocian (ca. 170 Ma) and suggests that the divergence time of the Pelliaceae is no later than the Middle Jurassic. 相似文献
9.
植物化石气孔参数分析是目前恢复古大气二氧化碳浓度较为精准的方法之一,银杏类和松柏类等是恢复古大气CO_2浓度常用的化石类群。本文利用新疆准噶尔盆地下侏罗统三工河组的松柏类掌鳞杉科Brachyphyllum(Hirmeriella?)sp.化石对早侏罗世大气CO_2浓度进行了重建,获得早侏罗世大气CO_2浓度为~1200ppm,丰富了早侏罗世大气CO_2浓度信息,进一步说明掌鳞杉科植物通过气孔比率法在重建侏罗纪大气CO_2浓度方面的可靠性。掌鳞杉科植物的旱生构造和较高的大气CO_2浓度表明早侏罗世Toarcian期大洋缺氧事件在陆地生态系统内可能产生了一定的响应。 相似文献
10.
陕西子洲县中侏罗统延安组砂岩中,同一地点共厚约1.7 m的5个层面发现4种食肉类恐龙足迹,自上而下分别为:1)第5层面大型三趾型足迹,实雷龙足迹科王氏子洲足迹(新遗迹属、新遗迹种)Zizhoupus wangi ichnogen.et ichnosp,nov.;2)第4和第3层面中型三趾型足迹,实雷龙足迹科龙尾峁张北足迹(新遗迹种)Changpeipus longweimaoensis inchnosp.nov.;3)第2层面小型三趾或四趾型足迹,虚骨龙类小理河陕西足迹(新遗迹种)Shensipus xiaoliheensis inchnosp.nov.;4)第1层面小型三趾型足迹,虚骨龙类的铜川陕西足迹Shensipus tungchuanensis. 相似文献
11.
快步麻蜥复合体(Eremias velox complex)分布于亚洲中部干旱区,不同地理居群形态和遗传变异较大。学界长期认为,快步麻蜥在我国有两个亚种:指名亚种(E.veloxvelox)和E.v.roborowskii亚种。前者分布于新疆准噶尔盆地和伊犁河谷;后者分布于新疆吐鲁番盆地,近年分类地位由亚种提升为种——吐鲁番麻蜥(E. roborowskii)。我们在吐鲁番市高昌区一万泉附近捕获到3只麻蜥,经过COI基因序列比对和系统发育关系重建以及外部形态比较,鉴定为快步麻蜥指名亚种。这是首次发现新疆天山以南存在快步麻蜥指名亚种分布,同时也确定为吐鲁番盆地的蜥蜴类分布新记录种,此发现可为研究快步麻蜥的谱系地理格局和演化历史提供基础资料。 相似文献
12.
This paper deals with some Middle Jurassic fossil plants from southern margin of the Eerduosi Basin. There are 36 species in 13 genus in this flora, i.e. Equisetum multi- dentatus Oishi, E. sp., Coniopteris hymenophylloides (Brongn.) Seward, C. bella Harris, C, burejensis (Zalessky) Seward, C. szeiana Choweet Yeh, C. tatungensis Sze, C. spp., Todites williamsoni (Brongn.) Seward, T. cf. williamsoni (Brongn.) Seward, Cladophle- bis asiatica Chow et Yeh, C. argutula (Heer) Fontaine, C. hsiehiana Sze, C. ( Gleichenites) takeyamae Oishi et Takahasi, C. cf. gracils Sze C. triangularis Oishi, C. grabauiana P’an C. cf punctata (Thoms) Chow et Yeh, C. spp., Baiera cf. concinna (Heer) Kawasaki, B. furcata (L. et H.) Braun, B. sp., Sphenobaiera longifolia (Pomel) Florin, Ginkgo obrutchewi Seward, G. sp., Phoenicopsis angustifolia Heer P. manchurica (Yo- koyama) Yabe, p. sp., Czekanowskia rigida Heer, C. sp., Pterphyllum sp., Elatocladus cf manchurica (Yokoyama) Yabe, E. sp., Podozamites lanceolatus (L. et. H.) Braun P. sp., Carpolithus sp. etc. The dominant groups of this flora are Filicopsida and Ginkgopsida. So it could be compared with the flora of Yanan Formation from inner Earduosi Basin and other floras from Northeast, Northwest and China, such as the floras of Dutung, Mentougon and Dongsheng etc. This flora is different from the Late Triassic flora and the Early Jurassic flora of North China. It belongs to the Coniopteris-Phoenicopsis flo- ra, which was assigned to Early-Middle Jurassic flora by Prof. Sze. But after studying, the authers believe that this flora should belong to Middle Jurassic rather than Early Jurassic. The climate was warm and damp in that time in North China. 相似文献
13.
Twenty-six species (or forms) of fossil pollen and spores referred to 24 genera extracted from the crude oil samples collected from the Yumen oil-bearing region in West Gansu are observed and the definition of the petroleum sporo-pollen assemblage is given by the authors. On the basis of palynological investigation, the oil source rock of this oil-bearing region is tentatively discussed in this paper. The fossil pollen and spores found from the Tertiary petroleum in this region may be divided into two groups, because they are extremely different in fossilized state. The group of spores and pollen with higher fossilized state is mainly consisted of Schizaeoisporites zizyphinus, Gibotiumspora paradoxa, Monosulcites minimus and Bennettiteaepollenites sp. The other group comprises Pinus, Picea, Ephedra, Potamogeton, Lilium, Ulmus, Chenopodium, Nymphaea, Eutrema, Lens, Nitraria, Tamarix, Achillea, Artemisia, Solidago, Bidens, Graminidites, Cypheraceaepollis, etc. The above mentioned petroleum sporo-pollen assemblage of the tertiary oil reservoir rock is a gathering of fossil pollen and spores brought from the Lower Cretaceous deposits and the tertiary deposits respectively. The appearance of the Early Cretaceous pollen and spores bearing in the black shales of the Lower Xinminbu Formation in the tertiary petroleum may be considered to be a result of petroleum migration. And it reflects that the oil source rock might belong to Early Cretaceous Series. The fossil pollen and spores extracted from the Early Cretaceous petroleum in this region contain merely Schizaeoisporites zizyphinus, Monosulcites minimus, Bennettiteaepollenites sp., Psophosphaera, etc. The tertiary pollen and spores are completely absent there. So it indicates that both the oil source rock and the oil reservoir rock should belong to the fossil-bearing Lower Xinminbu Formation. In addition, there are some pollen of Monosulcites and Psophosphaera in the petroleum reserved in the fissures of the Silurian metamorphic rock. They are also probably brought from the Lower Xinminbu Formation by oil and gas in the process of their migration. In any case, judging from the pollen and spores found from the crude oil, the oil source rock of this oil-bearing region is deduced to be the black shales of the Lower Xinminbu Formation referred to as Early Cretaceous Epoch. 相似文献
14.
Forty-seven species of fossil pollens and spores referred to 33 genera extracted from the crude oil samples collected from the Yecheng Seg of the Talimu Basin in Xinjiang were observed. Based on the investigation of the characteristics of the petroleum sporo-pollen assemblage, the problem on petroleum source of this oil-bearing region is discussed. The principle and method to judge source rock from petroleum sporo-pollen assemblage are specially explained in this paper. The petroleum sporo-pollen assemblage of the Neogene reservoir of the Yecheng Seg consists of Deltoidospora perpusila, Deltoidospora gradata, Cyathidites australis, Cyathidites minor, Biretisporites potoniaei, Dictyophyllidites harrisii, Dictyophyllum rugosum, Cibotiumspora paradoxa, Gleicheniidites senonicus, Gleicheniidites rousei, Undula- tisporites concave, Lycopodiumsporites sp., Osmundacidites wellmanii, Leptolepidites major, Apiculatisporis ovalis, Bennettiteaepollenites lucifer, Cycadopites typicus, Cyeadopites nitidus, Cycadopites minimus, Cycadopites carpentieri, Cycadopites follicularis, Chasmatosporites elegans, Classopollis classoides, Classopollis annulatus, Podocarpidites multesimus, Podocarpidites major, Parvisaccites enigmatus, Quadraeeulina limbata, Caytonipollenites pallidus, PteruchipoUenites thomasii, Alisporites grandis, Alisporites bilateralis, AbietineaepoUenites microalatus, Abietineaepollenites minimus, Pinuspollenites sp., Piceaepollenites sp., Cedripites st)., Ephedripites sp., Eucommiidites troedssonii, Magnolipollis neogenicus, Quercoidites microhenrici, Chenopodipollis multiplex, Artemisiae-pollenites sellularis, etc . This is a typical composite type of petroleum sporo-pollen assemblage, which eomprises the Jurassic species, the Cretaceous species, the Eogene species and the Neogene species of spores an, d pollen. In accordance with the characteristics of the above mentioned petroleum sporopollen assemblage, the source rock of the Yecheng Seg is considered to be Jurassic Period in age, and the black shales and mudstones of the Middle Jurassic Yangye-Taerga Formation are judged to be the most favorable source rocks in the region. 相似文献
15.
Hong-En Jiang David K. Ferguson Cheng-Sen Li Ye-Ming Cheng 《Review of Palaeobotany and Palynology》2008,150(1-4):37-47
Silicified coniferous wood was collected from the Lanqi Formation (late Middle Jurassic in age) at Shebudaigou Village, Liaoning Province, China. Three taxa are identified, namely Pinoxylon dacotense Knowlton, Xenoxylon phyllocladoides Gothan, and Araucariopitys sp. Based on these new data, and those of other fossil plants reported previously from the same formation, we consider the climate during the deposition of the Lanqi Formation was subtropical, humid and seasonal. In this respect the Lanqi flora differs from the coeval Shimengou and Longmen floras from North China. The Longmen flora was deposited during more humid, subtropical conditions, while the Shimengou Formation indicates that the climate was warm temperate and dry. Our data would suggest that the Late Jurassic climatic pattern was initiated as early as the late Middle Jurassic. 相似文献
16.
《Palaeoworld》2022,31(3):383-388
Gorgonopsians were widely distributed during the Permian, and went extinct by the end of Permian. However, their fossil localities in the North Hemisphere are concentrated in the eastern European portion of Russia, except for one possible canine from the North China. A specimen from the Wutonggou Formation of Turpan Basin, Xinjiang, China, dated ~253.3 Ma, is identified as a gorgonopsian based on dental features. This discovery shows that the gorgonopsians survived in northern warm temperate zone about ~253.3 Ma, contemporaneous with the latest records of Russia and South Africa. This specimen may represent one of the latest records of gorgonopsians. 相似文献
17.
2005年4月15日~2005年6月3日对中国科学院吐鲁番沙漠植物园及其周围地区的鼠类群落进行了调查,采用样线铗捕法,共捕获鼠类373只,隶属于3科3属4种。用种类(S)、多样性指数(H′)、均匀性指数(E)、优势度(D)等4个指标对灌木林、园林、沙地、废弃耕地、农田等5种不同生境类型的鼠类群落进行统计分析和对比。结果发现,不同生境类型的鼠类群落在群落组成、多样性、均匀性和优势度等方面存在着明显的差异;废弃耕地多样性和均匀性最高而优势度最低;园林多样性最低,农田均匀性最低,灌木林优势度最高。红尾沙鼠(Meriones libycus)和子午沙鼠(M.meridianus)分别占以上5种类型鼠类群落总生物量的59.5%和37.5%,可以确定为吐鲁番沙漠植物园及其周围地区鼠类群落的优势种。 相似文献
18.
19.
OLIVER W. M. RAUHUT† 《Palaeontology》2005,48(1):87-110
Abstract: A new taxon of theropod dinosaur is described as Condorraptor currumili gen. et sp. nov., from the Middle Jurassic (Callovian) Cañadón Asfalto Formation of Chubut Province, Argentinean Patagonia. The taxon is represented by a single fragmentary postcranial skeleton. Although incompletely known, Condorraptor is the second most complete theropod from the Middle Jurassic of Gondwana. The new taxon is characterized by the absence of a posterior incision between the fibular condyle and the medial side of the proximal articular end of the tibia, the pleurocoels in the anterior cervicals being situated posteroventral to the parapophyses, and the presence of a pronounced 'step' between the distal articular facet and shaft of Mt IV. Pneumatic features of the vertebral column show strong variation between the left and right side. Condorraptor gen. nov. can be referred to the Tetanurae and is a representative of a global radiation of basal tetanurans in the Early to Mid Jurassic. 相似文献
20.
The rate of taxic turnover of nearly 400 radiolarian species/subspecies is analyzed in order to document long term biotic change of plankton during the Middle Jurassic to Early Cretaceous (Aalenian to Aptian). The pattern and dynamic of diversity change is described using four indices: rate of species first and last occurrence, rate of diversification and rate of turnover. Plots of cumulative sampling effort suggest that the analyzed data represent an adequate sample of total standing diversity for most examined stages. Rates of species first occurrence exceed rates of last occurrence for most of the Middle Jurassic, except for the middle Bajocian. In contrast, the Late Jurassic was a time of decreasing radiolarian diversity and the Kimmeridgian records the lowest rate of diversification. It is followed by a dramatic increase in first occurrences near the Jurassic–Cretaceous boundary with as a result the highest rate of diversification recorded in the late Tithonian. Regional radiolarian diversity was stable throughout most of the Early Cretaceous. A stratigraphic permutation test was performed to assess the influence of uneven sampling on the observed pattern of taxic turnover and identified the intervals for which randomly obtained patterns are significantly different from the observed pattern. The Kimmeridgian and late Tithonian events coincide with substantial climate-derived perturbations in water cycling, nutrient supply and oceanic productivity. They point to a negative relationship between radiolarian macroevolution and changes in the state of nutrient availability, although further work is needed to refine the temporal resolution of this relationship and to explore ecological aspects of its causal link with respect to radiolarian evolution. 相似文献