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 31 毫秒
1.
Oxyporinae is a distinct staphylinid subfamily characterized by a large body, remarkably long and projecting mandibles, and large, crescent-shaped terminal labial palpomeres. Previously, only three compression fossils from the Lower Cretaceous Yixian Formation in China were known for the subfamily from the Mesozoic Era. This study describes a remarkable new species, Oxyporus cretaceous sp. nov., based on a single specimen in Upper Cretaceous Burmese amber. This finding is the earliest record of Oxyporinae preserved as amber inclusion. The well preserved mouthparts suggest that mycophagous feeding habits had already been acquired by the mid-Cretaceous.  相似文献   

2.
When most people hear the word 'fossil' they tend to conjure up images of giant dinosaurs such as Tyrannosaurus rex or shelled marine invertebrates. Prior to the Hollywood blockbuster movie Jurassic Park , which was based on recreating dinosaurs through extracting their DNA from fossil mosquitoes preserved in amber, few non-palaeontologists would entertain the notion that small, soft-bodied organisms such as insects occur in the fossil record. However, insects and spiders are common as fossils in amber, where they are often preserved with life-like fidelity, and they also occur to a lesser degree in carbonate rocks.  相似文献   

3.
The present paper refers to research conducted in the tectonic-karst depression of Campo Felice in the central Apennines (Italy), in which glacial, alluvial and lacustrine sediments have been preserved. Stratigraphic interpretations of sediments underlying the Campo Felice Plain are based on evidence obtained from nine continuous-core boreholes. The boreholes reach a depth of 120 m and provide evidence of five sedimentation cycles separated by erosion surfaces. Each cycle is interpreted as an initial response to a mainly warm stage, characterized by low-energy alluvial and colluvial deposition, pedogenesis, and limited episodes of marsh formation. In turn, a mainly cold stage follows during which a lake formed, and glaciers developed and expanded, leading to deposition of glacial and fluvioglacial deposits. The chronological framework is established by eleven accelerator mass spectrometer 14C ages and three 39Ar-40Ar ages on leucites from interbedded tephra layers. These age determinations indicate five glacial advances that respectively occurred during marine oxygen isotope stages 2, 3-4, 6, 10 and 14.  相似文献   

4.
随着琥珀市场需求的增加及琥珀优化处理技术的改进与创新,压制琥珀呈现外观逼真、结构复杂、方法多样的新态势。利用宝石显微镜、偏光显微镜、红外光谱仪对压制金珀、压制血珀、＂爆花＂压制琥珀、烤色压制琥珀、压固蓝珀、压固胶结蓝珀、压制蜜蜡等样品的宝石学参数、显微结构、红外吸收光谱进行了研究与分析,结果显示,碎粒-碎粉结构、红色斑点结构、不含＂血丝＂状构造的粒状＂镶嵌＂结构、碎块胶结结构等是压制琥珀的结构鉴定特征;颗粒间分布的＂太阳光芒＂、紊乱流纹、叶脉状流纹、丝瓜瓤状流纹等是压制琥珀的内含物鉴定特征;若蓝珀中的红外光谱I=2 932cm-1/I=1 723cm-1处的吸收强度比值接近1∶1,暗示着该蓝珀可能经过了优化处理。  相似文献   

5.
Millipedes (Diplopoda) are an important fossil group of land arthropods in the Palaeozoic. However, there is a gap in the Mesozoic, with only slightly more than a dozen fossils being known, until the much more recent fossil records mainly from Cenozoic Dominican and Baltic ambers become available. Burmese amber, precisely dated to the Late Cretaceous, is known for an apparently rich but still undescribed millipede fauna, and might represent the ideal bridge to close this gap in the millipede fossil record. In addition, modern micro-computed tomography (μCT) technology allows complex 3D reconstructions of objects fossilized in amber. Here we utilize μCT technology to describe the first millipedes from Burmese amber, which are also the first two fossil representatives of the order Siphoniulida. Siphoniulida, with two known species and just nine recorded specimens, are the rarest and least known of the 16 extant orders of the Diplopoda. Records are known from Sumatra, Guatemala and Mexico. The two new fossils described here represent two distinct species, Siphoniulus muelleri sp. nov. and S. preciosus sp. nov., and indicate a wider distribution of this order in the Cretaceous. The holotype of S. muelleri sp. nov. was well-enough preserved so that characters of the head, such as the incisura lateralis, not investigated before in extant representatives of the order, could be studied. This study highlights the possibilities and challenges provided by μCT technology in investigating Diplopoda fossilized in amber.  相似文献   

6.
New fossil material of ripiphorid beetles (Tenebrionoidea: Ripiphoridae) is described and figured in lowermost Cenomanian amber from the Hukawng Valley of northern Myanmar. Flabellotoma heidiae gen. et sp. nov. is the Mesozoic representative of the putatively primitive subfamily Pelecotominae, represented by an almost completely preserved male. The new genus is compared with all extant members of the subfamily and is most notably distinguishable by an autapomorphic combination of a reduced tibial spur formula and unique ventral abdominal sclerite, and presumably in antennal structure as well. In addition, a syninclusion of eight males of Ripidiinae is discussed. The males are similar to Paleoripiphorus deploegi Perrichot, Nel, et Néraudeau in roughly coeval amber from western France. The syninclusion is interpreted as a result of aggregative behaviour during the flight activity of males, thereby representing the earliest documented evidence of such ethology. Brief remarks are made regarding the similarities among Cretaceous amber beetle faunas, and Mesozoic taxa previously attributed to Ripiphoridae are newly reconsidered.  相似文献   

7.
Fossil insects from the Lower Cretaceous (Aptian) Crato Formation of north-east Brazil are preserved as goethite replacements in laminated limestones of lacustro-lagoonal origin. They display remarkable degrees of morphological detail down to the macromolecular level in some examples. We document the fidelity of preservation and reveal an astonishing variety of morphological detail comparable in some instances with that found in amber inclusions.  相似文献   

8.
DNA depurination and amino acid racemization take place at similar rates in aqueous solution at neutral pH. This relationship suggests that amino acid racemization may be useful in accessing the extent of DNA chain breakage in ancient biological remains. To test this suggestion, we have investigated the amino acids in insects entombed in fossilized tree resins ranging in age from <100 years to 130 million years. The amino acids present in 40 to 130 million year old amber-entombed insects resemble those in a modern fly and are probably the most ancient, unaltered amino acids found so far on Earth. In comparison to other geochemical environments on the surface of the Earth, the amino acid racemization rate in amber insect inclusions is retarded by a factor of >10(4). These results suggest that in amber insect inclusions DNA depurination rates would also likely be retarded in comparison to aqueous solution measurements, and thus DNA fragments containing many hundreds of base pairs should be preserved. This conclusion is consistent with the reported successful retrieval of DNA sequences from amber-entombed organisms.  相似文献   

9.
The first fossil Carabidae from Burmese amber is described as new to science, Oodes kachinensis Liu n. sp., based on a single individual preserved in Cretaceous amber from Myanmar. This species is placed in the extant tribe Oodini as supported by several characters: one supraorbital seta at each side of vertex, interval 9 very narrow, stria 8 very deep, epipleuron plica presented, antennomeres 1–3 glabrous and 4–11 densely pubescent. This new species has surprising long legs, indicating most probably it was living on the bank of puddle.  相似文献   

10.
Ninety rock samples from the La Granja porphyry copper in northern Peru have been analyzed for 30 elements, 10 of which are discussed here. Although intense weathering has produced a leached capping up to 200 m thick, the distribution of Mg, Ca, Na, K, Rb and Sr can still be correlated with different phases of hydrothermal alteration.There has been complete supergene leaching of sulphides; Cu has been depleted 10 to 30 times and Mo up to twice with respect to hypogene ore, Fe has been enriched in some parts of the leached capping, whereas Au remained stable. The coincidence of low Fe, high Mo and high Au contents with a high Cu/Fe ratio in the capping indicates the approximate centre of the underlying orebody. Also, high K, Rb, Mg and low Sr indicate high-grade copper ore.  相似文献   

11.
A hierarchical series of tidal periodicities are preserved within laminated tidal flat deposits at the barrier/back-barrier interface of Romney Marsh and the Dungeness Foreland in southeast England. The sedimentary record of the tidal signature, extracted from variations in sand layer thickness, was found to be severely truncated with neap-spring periods typically represented by five or less sand layers and possibly only alternate neap-spring periods present. Despite the low number of sand layers deposited in these higher frequency tidal cycles, semi-annual periods are clearly preserved but tend to contain less than the expected 6 months of sedimentation. Annual accumulation rates of around 0.2–0.3 m/year are indicated. Local emplacement of storm beaches is considered to have created the protected conditions suitable for tidal rhythmite preservation. Ongoing foreland progradation and infilling eventually restricted tidal inundation to the point where distinct sand laminae were no longer deposited. Here, in contrast with other systems, accommodation space was not limiting and tidal flat elevation is reflected as a more subtle control on spatial changes in the resolution of the tidal signal.  相似文献   

12.
  相似文献   

13.
Amber has fascinated people since the Stone Age and as one of the best means of preservation of fossil organisms, it tickles our senses. The animals that are sometimes trapped in amber, like frozen moments of long‐lost ecosystems, can be so incredibly well preserved that they look modern—which, in some cases, has proven to be just the case. Because fossil‐bearing amber not only has a significant scientific value but is also a desired commodity on the open market, fake amber has unfortunately been around for centuries.  相似文献   

14.
The Bittacidae (hangingflies) were abundant and widespread during the Mesozoic, but much of their diversity falls within the Jurassic whereas in the Cretaceous they are less common. A new bittacid, Burmobittacus jarzembowskii gen. et. sp. nov., is described from mid-Cretaceous amber from northern Myanmar. This new find is the first bittacid from Burmese amber and also the first Mesozoic bittacid preserved in amber. The new genus is distinguished from all known bittacids in having a long and narrow wing with Rs arising from R and forking very early (in the basal one-fourth of the wing), resulting in the stem of Rs being very short (about 1/8th of the length of Rs1+2), and stems of the main branches of Rs (Rs1+2 and Rs3+4) being unusually long.  相似文献   

15.
A Cretaceous amber deposit has recently been discovered in a quarry of Charente-Maritime (southwestern France), at Cadeuil. This paper presents the sedimentary and palaeoenvironmental settings of the uppermost Albian-lowermost Cenomanian series including the amber deposit. A preliminary analysis of the amber samples reveals diverse fossil arthropods (a few mites and at least 20 insect families within 9 orders), as well as numerous micro-organisms, mainly algae and mycelia. A myceloid colony of bacteria, a flagellate algae and four especially well preserved insects are illustrated (Diptera Dolichopodidae, Diptera Chironomidae, Hymenoptera Parasitica, and Heteroptera Tingidae). The abundance of the limnic micro-organisms is discussed in terms of bloom events. Their relative scarcity in almost all the amber pieces containing fossil arthropods is attributed to differences in the origin of resin: production along trunk and branches for amber with arthropods; production by aquatic roots for amber rich in algae. The absence of pollen and spores in amber is attributed to differences in the respective periods of resin and palynomorph production, which may be related to a seasonal climate during the Albian-Cenomanian transition in Western Europe.  相似文献   

16.
Two new genera with two new species in Berothidae, Maculaberotha nervosa gen. et sp. nov. and Magniberotha recurrens gen. et sp. nov., are described from Upper Cretaceous Myanmar (Burmese) amber. Based on the new specimens of the same species, we propose some venational characters as intraspecific variations, e.g., the markings on the wings and crossveins in the radial sector. We also study and compare the female genital sclerites from three genera of Haploberotha, Dasyberotha, and Jersiberotha to highlight the importance of using these characters preserved in amber for taxonomic and phylogenetic studies. Furthermore, an updated key to the berothid genera of Myanmar amber is provided.  相似文献   

17.
Layers with high magnetic susceptibility contain heavy minerals that are the most likely to preserve signatures of impact in metamorphosed Precambrian rocks. The following impact indicators are resistant to alteration and metamorphism and are likely to be found in heavy mineral layers: impact diamond, SiC, shocked zircon, high-pressure TiO2 phases, reidite, and high-pressure chromite. Coesite and stishovite could also be present but are not likely to be preserved in rocks metamorphosed above the greenschist facies. Looking for layers with high magnetic susceptibility will also identify layers that might contain concentrations of zircon for dating.  相似文献   

18.
A new genus with a new species, Brachypelecinus euthyntus gen. et sp. nov., and two new species, Abropelecinus tytthus sp. nov. and Zoropelecinus periosus sp. nov., are described and figured from three exquisitely preserved pelecinid wasps in the Upper Cretaceous Myanmar (Burma) amber. These taxa, owing to their well-preserved characters in amber, provide a better understanding of morphological changes and relationships among the constituent groups, while further highlighting the diversity of Pelecinidae in the Mesozoic.  相似文献   

19.
In September 1998 tropical storm “Earl” swept southern Mexico, producing intense rainfall in the states of Oaxaca and Chiapas. Among the most devastated cities was Motozintla, located in the drainage basin of the Allende, La Mina and Xelajú Grande Rivers. The rainfall from the tropical storm totaled 175 mm on September 8 and 130 mm on September 9, duplicating in two days the average monthly precipitation in the region. Numerous landslides occurred in the vicinity of Motozintla, depositing large volumes of material into the Xelajú Grande stream. Much of this sediment was subsequently remobilized, yielding debris flows, hyperconcentrated flows, and sediment-laden flows that inundated most sections of Motozintla city. The flows covered an approximate area of 3.15 km2 with a minimum volume of 4.4 × 106 m3 of sediment. Communication of Motozintla with the rest of the Chiapas State was interrupted for about a month, as was the supply of potable water, food, electricity, and fuel. The geologic record around Motozintla indicates that the Xelajú Grande River has been a pathway for similar large floods during the last 6000 years. The oldest deposit yielded a radiocarbon age of 5320 ± 100 14C years. B.P. At least two historic floods have occurred during the last 100 years, a time period defined by a stratigraphically distinct tephra of 1902. Frequency analysis of the historical record of daily rainfall in the Motozintla area suggests that events like that of September, 1998, have a recurrence interval of about 25 years. After the catastrophic flows of 1998, the mitigation measures by Municipal Authorities were made without regard to geological and environmental factors, or to taking into consideration the flow magnitude and appropriate hazard-mitigation techniques, with the result that Motozintla remains at serious risk for future floods. Unfortunately, prior to the publication of this study, in early October 2005, Motozintla was seriously damaged again by intense rain provoked by Hurricane Stan.  相似文献   

20.
《Gondwana Research》2008,13(4):571-575
Layers with high magnetic susceptibility contain heavy minerals that are the most likely to preserve signatures of impact in metamorphosed Precambrian rocks. The following impact indicators are resistant to alteration and metamorphism and are likely to be found in heavy mineral layers: impact diamond, SiC, shocked zircon, high-pressure TiO2 phases, reidite, and high-pressure chromite. Coesite and stishovite could also be present but are not likely to be preserved in rocks metamorphosed above the greenschist facies. Looking for layers with high magnetic susceptibility will also identify layers that might contain concentrations of zircon for dating.  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