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1.
A biostratigraphic study was carried out in the Lower Cretaceous Araripe basin, northeastern Brazil, allowing the recognition of several chronostratigraphic units: the Dom João (Jurassic?-Lower Cretaceous?), the Rio da Serra (Neocomian) and the Alagoas (Aptian/Albian) local stages. For the first time a large hiatus between the Rio da Serra and Alagoas local stages is carefully documented. The palynomorphs and the ostracode associations throughout the Jurassic?-Aptian/Albian sequence allow the interpretation of the paleoenvironmental evolution of the Araripe basin which otherwise confirms that a polycyclical sedimentation occurred in the basin, being one of the controlling factors on the distribution of ostracodes and palynomorphes. 相似文献
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M. Heldt M. Bachmann J. Lehmann 《Palaeogeography, Palaeoclimatology, Palaeoecology》2008,261(3-4):246-260
Upper Barremian–lower Upper Aptian hemipelagic deposits of the Hamada Formation in the Djebel Serdj area, north-central Tunisia were studied in detail with regard to microfacies, biostratigraphy, δ13C stratigraphy, and geochemistry. Our data provide insights into the palaeoenvironmental evolution and sea-level fluctuations of the Tunisian shelf. The unusually expanded deposits consist of mud-, wacke-, and packstones which reflect mid- and outer-ramp depositional environments. Planktonic foraminifer and δ13C stratigraphy allowed us to establish a detailed time-frame and the recognition of the Lower Aptian Oceanic Anoxic Event 1a (OAE 1a) as well as time-equivalent deposits of shallow-marine carbonate-platform drowning. Based on our microfacies studies, we subdivide the studied sections into four genetic intervals: a pre-OAE 1a interval, an OAE 1a and platform-drowning-equivalent interval, and a post-platform-drowning interval. We present a 3rd-order sea-level curve for the Tunisian shelf, deriving from the results of our microfacies studies.
Deposits of the OAE 1a in the sections investigated are characterised by bioclastic wacke- and packstones with high abundances of poorly preserved radiolarians and moderately to well preserved planktonic foraminifers, suggesting a transgression and an eutrophication of the upper water column. Scarceness of benthic macrofossils, low abundances of small benthic foraminifers and ostracods possibly suggest dysoxic conditions at the seafloor. Mudstones of the platform-drowning time-equivalent deposits, directly overlying the OAE 1a, are partly showing a pronounced drop in carbonate content and are scarce of macrofossils. 相似文献
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DAVID M. ROHR A. J. BOUCOT 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1989,22(2):213-215
Lopha ramicola Beurlen, 1964, from the Upper Cretaceous of Brazil is illustrated as an example of xenomorphism and bioimmuration on an unknown, possibly botanical, substrate not preserved in the fossil record. The shells preserve a sharp negative replica of the biologic substrate on the attached valve and a protruding positive replica, including a geometric pattern of nodes, on the unattached valve. 相似文献
5.
A 2700-year high resolution pollen record from annually-varved Sugan Lake in the Qaidam Basin at 2793 m a.s.l was obtained to examine vegetation and climatic change on the NE Tibetan Plateau. Pollen data shows that Sugan Basin was constantly covered by open desert-steppe vegetation dominated by Chenopodiaceae, Artemisia, Poaceae and Ephedra. However, large variations in Artemisia/Chenopodiaceae (A/C) ratios suggest regional moisture fluctuations over the last 2700 years, including a dry and relatively stable climate prior to 300 AD, relatively wet climate from 300 to 1200 AD with variability during 1100-1200 AD, and unstable climate since 1200 AD with relatively moister climate during 1250-1400 AD and 1700-1800 AD. However, other proxies (varve thickness, Chironomid taxa, isotopes of oxygen in precipitated carbonate) show fresher water when regional moisture was lower inferred from A/C ratio. This inconsistency suggests the possible difference of in-lake lithology/environment and regional moisture change. Fresh water into the lake from ice melting on the surrounding mountains might have contributed to the in-lake lithology and environment variation. The effective moisture changes in the Basin are in opposite phases to snow accumulation records from Dunde ice core (5325 m a.s.l) and to the monsoon intensity inferred from Dongge Cave, suggesting that the regional topography might have played an important role in mediating moisture changes at regional scale. Pollen data from Sugan Lake shows the shift of moisture at 1200 AD, from stable to variable conditions. This event is well correlated with other paleoclimate proxies in China and other parts of the world; however, the mechanisms behind these patterns require further investigation. 相似文献
6.
Julio Antonio Lombardi 《Brittonia》2004,56(3):288-290
A new species of Vitaceae is described and illustrated:Cissus xerophila, a simple-leaved species similar toC. verticillata (L.) Nicolson & C. E. Jarvis and related species. A key to the group in South America is presented. 相似文献
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A third species of the rare augochlorine bee genus Chlerogelloides Engel et al. (Halictinae, Augochlorini) is described and figured. Chlerogelloides nexosasp. n. is most similar to the type species, Chlerogelloides femoralis Engel et al., in that both have modified midlegs in the males. The former, however, can be distinguished on the basis of its terminalia, which in some respects more closely resembles those of Chlerogelloides simplex Engel and Brooks. Brief comments on the secondary features of males and relationships of the genus are provided. A key to the species of the genus is provided and floral records of Cordia nodosa Lam. (Boraginaceae) and Gonzalagunia dicocca Cham. & Schltdl. (Rubiaceae) are noted. 相似文献
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Carolina Silva de Oliveira Neubern Susana Trivinho-Strixino 《Studies on Neotropical Fauna and Environment》2013,48(1):26-35
Two new species of Parapentaneura Stur, Fittkau et Serrano, 2006 (Diptera: Chironomidae: Tanypodinae) from southeastern Brazil are described and figured as male, pupa and larva: P. brunnescens and P. flavescens. Keys to the males, pupae and larvae of known species of Parapentaneura are provided.http://www.zoobank.org/urn:lsid:zoobank.org:pub:E6860EBE-B781-4DDA-9650-6E6EA3A0309E 相似文献
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José Fernando A. Baumgratz 《Brittonia》2000,52(1):24-33
Two new Brazilian species of the genusHuberia,H. carvalhoi andH. consimilis, are described, discussed, and illustrated.Huberia carvalhoi is endemic to Bahia;H. consimilis has a wider distribution, with disjunct populations in Pernambuco, Bahia, and Rio de Janeiro. A key is provided to the three Bahia taxa with some comments on the taxonomic affinities of the two new species. 相似文献
11.
Oxygen and carbon isotope compositions of middle Cretaceous vertebrates from North Africa and Brazil: Ecological and environmental significance 总被引:1,自引:0,他引:1
Romain Amiot Xu Wang Eric Buffetaut Lionel Cavin Frédéric Fluteau Haiyan Tong 《Palaeogeography, Palaeoclimatology, Palaeoecology》2010,297(2):439-451
In order to investigate mid-Cretaceous terrestrial climates of low paleolatitudes, Moroccan, Tunisian and Brazilian vertebrate apatites have been analyzed for their oxygen and carbon isotope compositions of phosphates (δ18Op) and carbonates (δ18Oc, δ13Cc). At each site, coexisting theropod dinosaurs, titanosaurid sauropods, pterosaurs, crocodilians, turtles and fish have distinct δ18Op and δ13Cc values reflecting their ecologies, diets and foraging environments. Oxygen isotope compositions of surface waters (δ18Ow) estimated from turtle and crocodile δ18Op values range from − 5.0 ± 1.0‰ to − 2.4 ± 1.0‰, which do not differ from mean annual rainwater values occurring today under inter-tropical sub-arid to arid climates. High water temperatures ranging from 21 ± 6 °C to 34 ± 2 °C deduced from fish δ18Op values are in agreement with those published for mid-Cretaceous low latitudes. Temporary or seasonal droughts are inferred from high δ18Op values of lungfish teeth, even though lower reptile δ18Op values suggest the use of distinct and most likely larger or regularly renewed bodies of water. Environmental conditions of the studied low latitude regions during the Aptian-Cenomanian interval were somewhat similar to those experienced today under semi-arid to arid tropical or equatorial climates, but with higher mean surface temperatures than present-day ones. 相似文献
12.
Cutting More from Cut Forests: Edge Effects on Foraging and Herbivory of Leaf-Cutting Ants in Brazil
Edge-mediated changes in species composition are known to result in modified species interactions. Because of the crucial trophic position of herbivores and their far-reaching impact on plant communities, it is important to understand how edge influences herbivory. In the present paper, we investigated whether and how leaf-cutting ant foraging is altered in the forest edge, as this habitat is characterized by an increased proportion of pioneer species. We assessed basic foraging data as well as the herbivory rate ( i.e. , the proportion of the leaf material harvested by a colony in relation to the available leaf area in the foraging area) of Atta cephalotes colonies at the edge versus interior sites of a large remnant of the Atlantic forest in Northeast Brazil. Our results indicated clear edge effects on leaf-cutting ants: equally sized A. cephalotes colonies located at the forest edge removed about twice as much leaf area from their foraging grounds than interior colonies (14.3 vs. 7.8%/col/yr). This greater colony-level impact within the forest edge zone was a consequence of markedly reduced foraging areas (0.9 vs. 2.3 ha/col/yr) and moderately lower leaf area index in this habitat, whereas harvest rates were the same. Our results suggest that forest edges induce increased leaf-cutting ant herbivory, probably via the release of resource limitation. Together with the increase of leaf-cutting ant populations along forest edges, this may amplify environmental changes induced by habitat fragmentation. 相似文献
13.
Anastomoneura gen. nov. and A. guahybae sp. nov. are described and illustrated based on adult male and female specimens from the Mantiqueira mountain range, Minas Gerais State. This is the third genus recorded of the family Odontoceridae from South America. The new genus is characterized by the forewing anastomosis of veins R4 and R5 and male genitalia with a unique, tubular, projection dorsad to the plates of tergite X. 相似文献
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Dr. Michael W. Rasser 《Facies》2000,42(1):59-92
Summary Late Eocene sediments of the Upper Austrian Alpine Foreland Basin discordantly overlie Mesozoic and crystalline rocks, which
are deeply eroded and form a distinct pre-Eocene relief. Late Eocene deposits contain red algal limestones with a remarkable
lateral extent and a high diversity of sedimentary facies. Towards the south the algal limestones change into more clastic
sediments, which are characterized by larger foraminifera and bryozoans. Main components are coralline algal branches and
detritus, coralline crusts, rhodoliths, peyssonneliacean aggregates and crusts, nummulitid and orthophragminid foraminifera,
corals, bryozoans, as well as terrigenous components.
Rank correlation and factor analysis were calculated in order to obtain informations about relations between components. Hierarchical
cluster analysis allowed the designation of 17 facies, most of them are dominated by coralline algae. Actualistic comparisons
and correlations obtained from statistical analyses allowed the reconstruction of the depositional environments.
Main features of the northern area are huge accumulations of unattached coralline algae (branches, rhodoliths, detritus),
which are comparable to the present-day “Maerl”-facies. They formed loose frameworks cut by sand channels. The frequency of
coralline detritus decreases upsection. Peyssonneliacean algae in higher parts of the profiles show growth-forms that are
comparable to peyssonneliaceans of the Mediterranean circalittoral soft bottoms. This succession can be interpreted by an
increasing relative sea level. Besides, crustose coralline algal frameworks were growing on morphological highs which are
partially comparable to the present-day “Coralligéne de Plateau” of the Mediterranean Sea.
In contrast to the northern area, sedimentation rate of the southern area is too low to keep up with rising sea level. The
typical succession from nummulitid- to orthophragminid-and bryozoan-dominated facies can be interpreted by an increasing water
depth from shallowest subtidal to the deeper photic zone and finally to the aphotic zone. 相似文献
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William R. Anderson 《Brittonia》1994,46(2):126-133
Four species of Hiraea are described and discussed:H. gracieana andH. morii from Saül, French Guiana,H. longipes from the Oyapock region of French Guiana and Amapá, Brazil, andH. propinqua from French Guiana and Suriname.Hiraea gracieana is illustrated. 相似文献
17.
《Palaeoworld》2016,25(3):431-443
A cervical vertebra preserved at the famous and productive Cleveland-Lloyd Dinosaur Quarry in the Upper Jurassic Morrison Formation of Utah is that of an Apatosaurus, a sauropod dinosaur genus not previously recognized at the site and the first new dinosaur taxon identified at the site in years. The presence of Apatosaurus at a mudstone site dominated by other taxa, both theropod and sauropod, suggests a pattern of preservation within the Morrison Formation in which sites in fine-grained sediments yield dramatically uneven relative abundances of dinosaurs, with variable dominant taxa by site, compared with more time-averaged and attritional coarse-grained channel sandstone deposits. In addition, the continued demonstration of the wide-spread occurrence and abundance of Apatosaurus within the Morrison Formation, and the absence of its clade among diplodocid faunas on other continents, suggest that this group may have been endemic to North America during the Late Jurassic and that it may have originated there, though this is far from clear. 相似文献
18.
The fragmented Atlantic rain forest of Brazil: size, shape and distribution of forest fragments 总被引:6,自引:0,他引:6
PERTTI RANTA TOM BLOM JARI NIEMELA¨ ELINA JOENSUU MIKKO SIITONEN 《Biodiversity and Conservation》1998,7(3):385-403
The geographical characteristics of a total of 1839 forest fragments surrounded by sugar cane fields were studied in the Brazilian Atlantic rain forest region of the northeastern state of Pernambuco. The size and shape of the fragments as well as inter-fragment distances and the effects of varying edge width were examined using a geographical information system. The analyses show that the fragments are relatively small and close to each other. Approximately 48% of the rain forest fragments are <10 hectares, while only about 7% are >100 hectares. Forest fragments are close to each other, as fragments located 50m or less apart formed groups that included ca. 50% of the total forest area. At 350m inter-fragment distance, 98% of the rain forest area was included in groups of fragments. Due to the small size and irregular shape of the fragments, the total area of edge zone exceeds that of the interior habitat when the edge width is ca. 60m. At an edge width of 300m ca. 94% of the total fragment area is edge zone. For conservation purposes, ways of establishing networks of forest fragments connected by corridors and stepping stone fragments are demonstrated using GIS. Simulations using these techniques show that reforestation of sugar cane fields between the forest fragments would considerably increase the area of interior forest habitat and connectivity between fragments. 相似文献
19.
Paola Marchesini Fabio Trindade Maranh?o Costa Claudio Romero Farias Marinho/ 《Memórias do Instituto Oswaldo Cruz》2014,109(5):706-708
In Brazil, malaria remains a disease of major epidemiological importance because ofthe high number of cases in the Amazonian Region. Plasmodium spp infections duringpregnancy are a significant public health problem with substantial risks for thepregnant woman, the foetus and the newborn child. In Brazil, the control of malariaduring pregnancy is primarily achieved by prompt and effective treatment of the acuteepisodes. Thus, to assure rapid diagnosis and treatment for pregnant women withmalaria, one of the recommended strategy for low transmission areas by World HealthOrganization and as part of a strategy by the Ministry of Health, the NationalMalaria Control Program has focused on integrative measures with woman andreproductive health. Here, we discuss the approach for the prevention and managementof malaria during pregnancy in Brazil over the last 10 years (2003-2012) usingmorbidity data from Malaria Health Information System. Improving the efficiency andquality of healthcare and education and the consolidation of prevention programmeswill be challenges in the control of malaria during pregnancy in the next decade. 相似文献
20.
We report a new pleurodiran turtle from the Barremian Morro do Chaves Formation, Sergipe-Alagoas Basin, Brazil. We tested the phylogenetic position of Atolchelys lepida gen. et sp. nov. by including it in a comprehensive cladistic analysis of pleurodires. The new species is a basal member of Bothremydidae and simultaneously the oldest unambiguous crown Pleurodira. The biogeographic and chronostratigraphic significance of the finding has implications for the calibration of molecular clocks studies by pushing back the minimum age of crown Pleurodira by more than 12 Ma (ca 125 Ma). The reanalysis of Pelomedusoides relationships provides evidence that the early evolution and relationships among the main lineages of side-necked turtles can be explained, at least partially, by a sequence of vicariance events. 相似文献