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1.
VERTEBRATES FROM THE WOOD BAY GROUP AND THE POSITION OF THE EMSIAN-EIFELIAN BOUNDARY IN THE DEVONIAN OF VESTSPITSBERGEN 总被引:1,自引:0,他引:1
This paper deals with various vertebrates from the Verdalen Member of the Stjørdalen Formation of the Wood Bay Group, Vestspitsbergen, or layers presumably belonging to this member, including the thelodont scales Amaltheolepis winsnesi n.g., n.sp. (earlier known from a locality in Sørkapp Land), the heterostiid brachythoracid Herasmius granulatus n.g., n.sp. and the porolepiform crossopterygian Heimenia ensis n.g., n.sp., the latter with scales intermediate in some ways between those of Porolepis on the one hand, and the Holoptychiidae on the other. Amaltheolepis and Herasmius are not yet known to occur outside Vestspitsbergen; Heimenia is represented in a Devonian material from Anderson River, Northwestern Canada and perhaps also in the Placo-derm Sandstone of Poland. A critical appraisal of the arthrodire faunas of the Wood Bay Group shows that most of the earlier recorded occurrences of Homostius and Heterostius in these layers pertain to euleptas-pid brachythoracids, that the Heterostiidae and Homostiidae are also represented, but only in the Stjordalen Formation, and that the youngest member of the Euleptaspididae, occurring in the Stjordalen Formation, may be closely related to another euleptaspid in the Upper Emsian Heisdorf Beds of the Rhinish sequence (which occurs in association with Ohiolepis scales). The palaeontological evidence may indicate that the Wood Bay Group does not belong to the Lower Devonian in its entirety but includes Middle Devonian strata in its uppermost part. 相似文献
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中国蝠蛾属昆虫的种类和地理分布研究 总被引:22,自引:0,他引:22
中国分布的蝠蛾属Hepialus(鳞翅目:蝙蝠蛾科),是一类重要的资源昆虫,其幼虫被中华虫草菌Cordyceps sinensis(Berk.)Sacc.寄生感病后形成的虫菌结合体,是我国特产的名贵药材-冬虫夏草。在我国,已知蝠蛾36种,所有的种类均为古北种;其中33种是青藏高原地区分布种,是中国的特有类群,占已知种的91.7%;中亚地区种2个,占5.6%;欧亚地区分布种1个,占2.7%。我国的蝠蛾属主要分布于青藏高原内的西藏、青海、云南、四川、甘肃等省(区)的高寒草甸之中;零星分布于新疆、黑龙江、 内蒙古等省(区)的草原中;全部种类都营土壤内生活。在我国,95%的蝠蛾种类分布区域十分狭窄,常常是不同山脉就形成不同的种类,甚至是同一山脉不同坡向、不同海拔就会形成完全不同的种类。该属昆虫在中国的分布中心是青藏高原东部的横断山系内,位于北纬27°-33°,东经95°~103°之间的区域中,占已知种的80%。蝠蛾垂直分布明显,分布下限在纬度偏南地区海拔约3000m,而偏北地区则约2500m; 分布上限为海拔5100m; 最适分布海拔在4000-4800m之间;最适分布土壤是高山草甸土。蝠蛾的生态地理分布主要受食物、植被、土壤结构、温湿度等生态因子的影响。 相似文献
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Abstract: The hitherto poorly known, monotypic trilobite genus Fenestraspis from the Lower Devonian of Bolivia is revised and its original assignment to the Synphoriinae supported. The thoracic morphology of the genus remains very poorly known. Fenestraspis is morphologically unusual because of the development of extensive fenestrae in the pleural region of the pygidium and apparently of the thorax; the presence of upwardly directed spines on the cephalon, thorax and pygidium; and the exceptionally large and highly elevated eyes with the palpebral rim projecting outwards above the visual surface. The function of the fenestrae remains uncertain. If they formed openings in the body of the trilobite in life they may have allowed circulation of oxygenated water to the limb exites so that respiration could have been maintained while the trilobite was enrolled. If they were covered with a flexible membrane, they may have been secondary respiratory structures or had a sensory function. The Synphoriinae is regarded as a subfamily of the Dalmanitidae rather than as an independent family of the Dalmanitoidea as proposed by some authors. The type species of the poorly known monotypic genus Dalmanitoides from the Lower Devonian of Argentina is illustrated photographically for the first time and compared with Fenestraspis . 相似文献
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THE NARWHAL, MONODON MONOCEROS, IN THE NORWEGIAN HIGH ARCTIC 总被引:1,自引:0,他引:1
Narwhals ( Monodon monoceros ) are known to frequent the waters of the Norwegian arctic archipelago of Svalbard. An attempt is made to summarize narwhal observations from the Svalbard area, and from this to deduce their distribution. Observations have been gathered from the literature, sealing vessel log books and official statistics. Interviews have also been conducted with residents of Svalbard. I con&de that narwhals are most frequently observed in the area off the north-west corner of Spitsbergen. 相似文献
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Age distribution theory has been employed in a model to analyse a variety of histograms of the DNA content of single cells in samples from experimental tumours growing in tissue culture. The method has produced satisfactory correspondence with the experimental data in which there was a wide variation in the proportions of cells in the intermitotic phases, and generally good agreement between the 3H-thymidine labelling index and the computed proportion in S phase. The model has the capacity to analyse data from populations which contain a proportion of non-cycling cells. However, it is concluded that reliable results for the growth fraction and also for the relative durations of the intermitotic phase times cannot be obtained for the data reported here from the DNA histograms alone. To obtain reliable estimates of the growth fraction the relative durations of the phase times must be known, and conversely, reliable estimates of the relative phase durations can only be obtained if the growth fraction is known. 相似文献
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by IVAN J. SANSOM C. GILES MILLER† ALAN HEWARD‡¶ NEIL S. DAVIES GRAHAM A. BOOTH‡ RICHARD A. FORTEY† FLORENTIN PARIS§ 《Palaeontology》2009,52(2):337-342
Abstract: Over the past three decades Ordovician pteraspidomorphs (armoured jawless fish) have been recorded from the fringes of the Gondwana palaeocontinent, in particular Australia and South America. These occurrences are dominated by arandaspid agnathans, the oldest known group of vertebrates with extensive biomineralisation of the dermoskeleton. Here we describe specimens of arandaspid agnathans, referable to the genus Sacabambaspis Gagnier, Blieck and Rodrigo, from the Ordovician of Oman, which represent the earliest record of pteraspidomorphs from the Arabian margin of Gondwana. These are among the oldest arandaspids known, and greatly extend the palaeogeographical distribution of the clade around the periGondwanan margin. Their occurrence within a very narrow, nearshore ecological niche suggests that similar Middle Ordovician palaeoenvironmental settings should be targeted for further sampling. 相似文献
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Abstract: British Llandovery crinoids remain poorly known. Three species are documented herein that were originally described, but not published, by W. H. C. Ramsbottom. Clematocrinus ramsbottomi Fearnhead sp. nov. (Tortworth Inlier, Gloucestershire; Telychian) has a heteromorphic column, N434243414342434, radices directed away from the crown, and ten long, uniserial arms with a pustular aboral sculpture and long, slender pinnules. Clematocrinus spp. are widely distributed in the Silurian of England. Ptychocrinus mullochillensis Fearnhead and Donovan sp. nov. (Girvan district, Strathclyde; Rhuddanian) is the second report of this Upper Ordovician–Lower Silurian genus from outside North America. Although incompletely known, this species is distinguished by its hidden infrabasals, 20 arms and sunken interbrachial plates with a strongly stellate sculpture. Petalocrinus bifidus (Bather MS) Donovan and Fearnhead sp. nov. (Woolhope Inlier, Herefordshire; Telychian) is locally common enough to give its name to a mappable lithostratigraphic unit, the Petalocrinus Limestone. Unlike other Petalocrinus species known from the Silurian of China, northern Europe and North America, the fused arms of P. bifidus are divided in two by a proximal adoral ridge and an associated distal notch. Unlike extant crinoids, Petalocrinus probably lived as a rheophobe; the fused arms may have acted to deter predators. 相似文献
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A CONTRIBUTION TO THE ORNITHOLOGY OF THE TRISTAN DA CUNHA GROUP. 总被引:1,自引:0,他引:1
《Ibis》1957,99(4):545-586
Based on work during residence from January 1950 to October 1952, a revised check-list is presented for the Tristan Group, together with field and taxonomic notes on the individual species. Only two subspecies of birds, other forms of which survive elsewhere in the group, are known to have become extinct during the century and a half of human settlement. 相似文献
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Elizabeth N. Marks 《Australian Journal of Entomology》1968,7(1):43-56
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Culiseta arenivaga sp.n., described from females from Fraser Island, Queensland, provides the northernmost record of Culiseta in Australia. C. arenivaga has postspiracular setae and it is compared in text and figures with the other species known from Queensland, C. antipodea Dobrotworsky, and with the other species possessing postspiracular setae, C. littleri (Taylor), C. inconspicua (Lee), and C. atra (Lee), of which the first two are the only species known from New South Wales. Postspiracular setae are reported in C. inconspicua for the first time. C. littleri is recorded from northern New South Wales and geographical variation in this species is discussed. The unusual palmate empodium of C. antipodea females is described and figured. Relationships within the genus are considered and an austral origin for the genus is suggested. 相似文献
Culiseta arenivaga sp.n., described from females from Fraser Island, Queensland, provides the northernmost record of Culiseta in Australia. C. arenivaga has postspiracular setae and it is compared in text and figures with the other species known from Queensland, C. antipodea Dobrotworsky, and with the other species possessing postspiracular setae, C. littleri (Taylor), C. inconspicua (Lee), and C. atra (Lee), of which the first two are the only species known from New South Wales. Postspiracular setae are reported in C. inconspicua for the first time. C. littleri is recorded from northern New South Wales and geographical variation in this species is discussed. The unusual palmate empodium of C. antipodea females is described and figured. Relationships within the genus are considered and an austral origin for the genus is suggested. 相似文献
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J. D. Macdonald 《Ostrich》2013,84(4):195-196
This study investigates the possibility of hybridisation between introduced domestic Helmeted Guineafowl Numida meleagris, derived from the West African subspecies N. m. galeata, and South African guineafowl, N. m. coronata. There is putative morphological evidence of such hybridisation in wild populations and it is known that domestic guineafowl do not survive well in the wild. Molecular analysis of the control region of mtDNA confirmed the occurrence of the domestic guineafowl haplotype in individuals present in wild populations from KwaZulu-Natal, but not in birds from populations from the Free State. Thus, despite the absence of the availability of bi-parentally inherited nuclear DNA marker, the presence of the domestic haplotype in individuals of both wild and intermediate phenotype (between wild and domestic birds) suggests that there is hybridisation in the wild between domestic and wild guineafowl. To avoid potential negative affects associated with outbreeding depression, we argue for careful control of releases of domestic guineafowl into the wild. This study investigates the possibility of hybridisation between introduced domestic Helmeted Guineafowl Numida meleagris, derived from the West African subspecies N. m. galeata, and South African guineafowl, N. m. coronata. There is putative morphological evidence of such hybridisation in wild populations and it is known that domestic guineafowl do not survive well in the wild. Molecular analysis of the control region of mtDNA confirmed the occurrence of the domestic guineafowl haplotype in individuals present in wild populations from KwaZulu-Natal, but not in birds from populations from the Free State. Thus, despite the absence of the availability of bi-parentally inherited nuclear DNA marker, the presence of the domestic haplotype in individuals of both wild and intermediate phenotype (between wild and domestic birds) suggests that there is hybridisation in the wild between domestic and wild guineafowl. To avoid potential negative affects associated with outbreeding depression, we argue for careful control of releases of domestic guineafowl into the wild. 相似文献
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广西瓜馥木的新黄酮成分 总被引:3,自引:0,他引:3
从广西瓜馥木茎皮的乙醇提取物中分到6个黄酮成分,其中瓜馥木甲素为一新黄酮,经各种波谱解析及化学转换方法,其结构鉴定为8-羟基-5,6,7-三甲氧基双氢黄酮(1)。 相似文献
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台湾原为大陆的一部分,以后由于断陷而形成台湾海峡。台湾海峡两岸植物区系关系密切,植物区系相互迁移分布,闽台陆桥是台湾海峡最浅的部分,在更新世冰期,由于海退,陆桥曾4次较长时间露出水面,成为台湾海峡两岸植物区系迁移分布的通道,使得两岸植物的迁移分布得以进行。 相似文献
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MARTIN J. M. BLESS HANSPETER JORDAN 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1971,4(2):185-190
A palaeocope ostracode with prominent cruminal dimorphism occurs in Lower Carboniferous strata of Nova Scotia and Ireland. It is believed to be the youngest representative of the Beyrichiidae Matthew 1886, a family hitherto only known from the Silurian and Devonian. Because of differences in lobation and adventral structures this ostracode is here assigned to the new genus Copelandelia. The occurrence of the type species Copelandelia novascotica in strata of comparable age (Viséan) in Nova Scotia and Ireland appears to add some support to the hypothesis that North America and Europe formed one supercontinent in the Paleozoic, since this species is assumed to have lived in a near-shore, or even a brackish or non-marine environment. 相似文献
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EVOLUTIONARY TRENDS IN THE GENUS GINKGO 总被引:5,自引:0,他引:5
Three main independent phylogenetic groups within Ginkgoales , consisting of different families, are suggested. It is considered impossible to deduce the genus Ginkgo from any other genus by means of fossil evidence known at present.
The oldest finds of Ginkgo date from the Lower Jurassic. During the Cretaceous, increasing polymorphy in foliar remains indicates the rise of new species. During the Lower Cretaceous there also appears a type of leaf known both as G. adiantoides and as G. paradiantoides. This leaf is from the gross morphological and the anatomical point of view almost identical with the Tertiary and Recent Ginkgo populations, thus making a direct ancestry between the present-day Ginkgo and those of the Lower Cretaceous likely. By Lower Tertiary times a considerable reduction has taken place leaving only one gross morphological type of leaf, that of G. adiantoides. This is suggested to be identical with G. biloba. Although there is no positive evidence, it can be assumed that the final reduction of the genus, to its present-day East Asiatic home, has taken place during the Pleistocene period. 相似文献
The oldest finds of Ginkgo date from the Lower Jurassic. During the Cretaceous, increasing polymorphy in foliar remains indicates the rise of new species. During the Lower Cretaceous there also appears a type of leaf known both as G. adiantoides and as G. paradiantoides. This leaf is from the gross morphological and the anatomical point of view almost identical with the Tertiary and Recent Ginkgo populations, thus making a direct ancestry between the present-day Ginkgo and those of the Lower Cretaceous likely. By Lower Tertiary times a considerable reduction has taken place leaving only one gross morphological type of leaf, that of G. adiantoides. This is suggested to be identical with G. biloba. Although there is no positive evidence, it can be assumed that the final reduction of the genus, to its present-day East Asiatic home, has taken place during the Pleistocene period. 相似文献
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黄皮树果实中的酰胺类化合物 总被引:2,自引:0,他引:2
黄皮树(PhellodendronchinenseSchneid.)属芸香科黄檗属植物,树皮为中药黄柏。我们曾从其树皮中提取到数种三萜类的昆虫拒食物质[1],继而从其干果中分离到数种拒食物质[2]。本文报道从干果中分离到的酰胺类化合物,它们是:反,反-2,4-N-异丁基十四碳二烯酰胺(1),反,反,顺-2,4,8-N-异丁基十四碳三烯酰胺(2),反,反-2,4-N-异丁基十五碳二烯酰胺(3)和N-methylflindersine(4)。其中,反,反,顺-2,4,8-N-异丁基十四碳三烯酰胺是一… 相似文献
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NinaM. Young G. Marion Hope WilliamW. Dawson RobertL. Jenkins 《Marine Mammal Science》1988,4(4):281-290
The pygmy sperm whale ( Kogia breviceps ) and the bottlenose dolphin ( Tursiops truncatus ) are equipped with a tapetum fibrosum and, with other Cetacea, are the only carnivores known to possess this typically ungulate tapetal type. Tapeta from two regions of a retina, each with a different spectral reflectance (blue and green), were found to have significantly different fibrillar diameters and inter-fibrillar spacing. When the measured values are applied to a dielectric reflector model, the predicted wavelengths agree with the observed reflectance of the flat-mounted tapeta. The spatial properties of the fibrils change progressively from the tapetal origin in the fibroblast layer to the pigment epithelium, suggesting that different wavelengths may be reflected systematically with tapetal depth. The very large number of reflecting layers characterizing these tapeta, relative to those of other carnivores, may provide for increased spectral purity and efficiency. 相似文献
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SVEND ERIK BENDIX-ALMGREEN 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1971,4(1):21-49
The two best preserved specimens of the Upper Permian fish Menaspis armata have been reinvestigated, resulting in new interpretations of a variety of anatomical features. The conclusion is reached that the menaspids cannot possibly be closely related to the chimaeriforms (myriacanthids, squalorajids, and chimaerids), nor to any of those better known bradyodonts (chondrenchelyids, helodontids or edestids) with which they were previously classified. Among the bradyodonts, their closest relatives are probably to be found within the cochliodontids. As far as other elasmobranchiomorphs are concerned, the menaspids may be somehow related to, though surely not direct descendants of, the rhenanids, and it is conceivable that both these groups are derived from the same ancestral forms among the early arthrodires or the arthrodire predecessors. 相似文献