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1.
The study of mammalian faunas has contributed widely to the knowledge of palaeoenvironments during the Quaternary. The cenogram method, a graphical representation of the mammalian community structure, permits the reconstruction of the environments and the inference of the climatic conditions. This method has the advantage of taking into account all the mammals present in a fossil locality. Applied on several faunas of the South of France, this method shows different phases in the climatic and environmental changes during the Pleistocene. From the setting-up of glacial cycles in the Pleistocene, the conditions become colder and there is an alternation between a rather closed environment during the interglacial periods and a more open landscape during the coldest periods of the Pleistocene.  相似文献   

2.
Summary First true coral reefs in Australia appear in the Silurian of northern Queensland. The reef belt then advances to the south and reaches its maximum in the Middle Devonian. In the Upper Devonian and Lower Carboniferous reef-building activity is again restricted to the north. Reefs are unknown from the Upper Carboniferous until the middle Tertiary. The southern limit of the reef belt advances along the west coast, possibly since the Miocene and reaches its extreme southerly position (32° S. lat.) in the late Pleistocene, probably the last Interglacial. Since then it has moved northward to 29° N. lat. In the east the Great Barrier Reef reaches southward as far as 24° N. lat. and no more southerly reefs of Pleistocene or Recent age are known. The significance of these facts for the theory of continental drift is difficult to assess. The Pleospongia (Archaeocyathinae) of the Cambrian are not reef-builders and their distribution could be satisfactorily explained by assuming that they were restricted to the temperate belts in both hemispheres. Conditions in the Middle Devonian with their extraordinary expansion of reef-building organisms require special explanation, but before a shift of the Australian continent relative to the climatic belts is accepted, it is neccessary to study the very irregular course of the limits of the present reef belt. Comparing marine faunas of similar latitudes today one may encounter differences perhaps not less profound than those between Devonian faunas in comparable belts.  相似文献   

3.
Data from the mammal fauna of the North Urals during the Late Pleistocene and Holocene are synthesised. Analysis of differentiation the degree of small- and large-mammal faunas during this time has been undertaken. Only differences of mammal species composition were significant between the Late Pleistocene and Holocene complexes, and within these complexes, the distinction between faunas was insignificant. The transition from the Late Pleistocene to the Holocene complex small-mammal faunas occurred in the Middle Late Valdai due to expansion of the forest species. In large-mammal faunas, the process was recorded later (in Dryas 3-Early Holocene) because of the extinction of some species and others that changed their areas of occupation.  相似文献   

4.
Systematic studies of the Pleistocene mammal assemblages of Eastern Europe have been carried out for more than a century, and they elucidated evolutionary changes and ascertained chronological sequence of the faunas. The available evidence on fossil mammals from Eastern Europe allows differentiation of 7 complexes of large mammals. These complexes represent 15 assemblages and their phases distinguished for small mammals. The appearance of new taxa of different rank provides the basis for identification of the principal stages in mammal evolution. Multi-disciplinary studies of fossil mammal localities have made it possible to correlate theriological data with the main events of the Pleistocene (such as glacials and interglacials) by comparison between geological, geochronological and palaeontological data.Interglacial and periglacial mammal faunas of different age have been defined on the basis of their structural characteristics and geographical distribution. Two types of mammal assemblages are recognised: zonal interglacial and periglacial assemblages specific to glacial periods. In the first type, each zonal assemblage is dominated by a single ecological group of mammals. A distinctive feature of the second type is the co-existence of animals belonging to different ecological groups and inhabiting different natural environments.  相似文献   

5.
 Oligocene and Early Miocene coral assemblages from three sections of central Iran are investigated with respect to their palaeoecological and palaeobiogeographic implications. These corals are compared with faunas from the Mediterranean Tethys and the Indopacific. Associated larger foraminifers are used for biostratigraphy and to support the palaeoecological interpretation. The studied sections are situated in the foreland basins of the Iranian Plate which is structured into a fore-arc and a back-arc basin separated by a volcanic arc. The coral assemblages from Abadeh indicate a shallowing-upward trend. Infrequently distributed solitary corals at the base of the section indicate a turbid environment. Above, a distinct horizon characterised by a Leptoseris-Stylophora assemblage associated with lepidocyclinids and planktonic foraminifers is interpreted as maximum flooding surface. Small patch reefs with a Porites-Faviidae assemblage are a common feature of Late Oligocene to Early Miocene coral occurrences and indicate water depths of less than 20 m. The diversity of the coral faunas shows marked differences. Oligocene corals from the Esfahan-Sirjan fore-arc basin comprise more than 45 species of 32 genera and occur in a wide range of environments. Early Miocene corals from the Qom back-arc basin are less frequent, show a lower diversity (13 genera with 15 species) and occur in single horizons or small patch reefs. Received: 4 December 1998 / Accepted: 3 June 1999  相似文献   

6.
In Tasmania sedimentary rocks containing shelly fossils at many horizons, some graptolitic horizons and numerous conodont horizons were deposited, apparently continuously, from the Tremadoc Epoch into and after the Llandovery Epoch. Superposition can be demonstrated over this interval so that the position of preserved faunas or biotas relative to one another is clear in most cases. Twenty successive Ordovician faunas are recognized. During the interval represented by this succession the geographical affinities of the faunas were generally with eastern Asian, North American and South American faunas, but in the later part of the Ordovician and in the Silurian the affinities were wider. Because of the clarity of the succession, the duration of deposition and relationships of the faunas, the Tasmanian succession is likely to be a useful link in world correlation, especially for isolated areas such as parts of South America and southeastern Asia.  相似文献   

7.
The Pleistocene ungulate communities from the western coastal plains of South Africa's Cape Floristic Region (CFR) are diverse and dominated by grazers, in contrast to the region's Holocene and historical faunas, which are relatively species-poor and dominated by small-bodied browsers and mixed feeders. An expansion of grassy habitats is clearly implied by the Pleistocene faunas, but the presence of ruminant grazers that cannot survive the summer dry season typical of the region today suggests other important paleoecological changes. Here we use dental ecometrics to explore the paleoecological implications of the region's Pleistocene faunas. We show that the dental traits (hypsodonty and occlusal topography) of the ungulates that occurred historically in the CFR track annual and summer aridity, and we use these relationships to reconstruct past aridity. Our results indicate that the Pleistocene faunas signal paleoenvironments that were on average less arid than today, including during the summer, consistent with other lines of evidence that suggest a higher water table and expansion of well-watered habitats. Greater water availability can be explained by lower temperature and reduced evapotranspiration during cooler phases of the Pleistocene, probably coupled with enhanced groundwater recharge due to increased winter precipitation.  相似文献   

8.
周口店地区第四纪哺乳动物群的演化与环境变迁探讨   总被引:2,自引:0,他引:2  
程捷  田明中 《现代地质》1996,10(2):202-212
讨论了Alilepusannectens、HypolagusbrachypusLepussp.、Sciurotamiaspraecox、AllocricetusteilhardiCricetinusvarians、Hyperacriusyenshanensis、Allophaiomyscf.pliocaenicus、Proedromyscf.bedfordi、Chardinomysnihewanicus、Muscf.musculus和Apodemusdominans的地史分布。根据哺乳动物群的分析与对比,得出第18地点为早更新世早期,第12地点、东洞地点为早更新世中期,第9地点、西洞地点为早更新世晚期,第13地点为早更新世末期至中更新世初期,第1、2、5、6、11、10、21、23及上店洞地点为中更新世,新洞为中更新世晚期至晚更新世早期,东岭子洞为晚更新世,山顶洞为晚更新世晚期。还讨论了周口店地区一些主要第四纪哺乳动物群的生态类型特点,第四纪的气候波动及生态环境变迁。  相似文献   

9.
第四纪期间中国南北两大动物区系之间的过渡地带动物群   总被引:6,自引:0,他引:6  
计宏祥 《地层学杂志》1994,18(4):248-254
中国第四纪期间的哺乳动物,可划分为南、北两大动物群,在两大动物群之间,存在过渡地带动物群。过渡地带的动物群,晚更新世的有河南新蔡、安徽五河戚咀及江苏武进;中更新世地点有安徽和县、巢县银山、河南南召及江苏南京汤山;早更新世地点有安徽巢县银山下部堆积、陕西蓝田公王岭及汉中盆地的勉县。裴文中(1957)首先提出淮河过渡区的存在,周明镇等认为不存在。事实上过渡地带的南、北混生动物群是存在的,过渡地带的范围大小及地点是随着地史的变迁而不断的变化。四不象鹿是过渡地带生活的一种特殊动物,而众多的古人类化石在过渡地带发现,也是这一地区的一个特色。  相似文献   

10.
Calcareous aeolianites are an integral part of many carbonate platforms and ramps. Such limestones are particularly common in heterozoan, Late Cenozoic carbonate systems, and it has been postulated that they could contain a particularly sensitive record of their offshore source. This hypothesis is tested herein by documenting and interpreting part of the most extensive and temporally longest such system in the modern world. The deposits are a combination of extraclasts and biofragments. Extraclasts are detrital quartz, relict allochems, older Pleistocene particles and Oligocene–Miocene limestone clasts. Biofragments are penecontemporaneous coralline algae, echinoderms, small benthic foraminifera, molluscs and bryozoans. The aeolianites differ in composition from distant, open shelf sediments because they contain more mollusc fragments and many fewer bryozoans. This difference is interpreted to be due to (i) most sediment was derived from near‐shore seagrass meadows and macroalgal reefs; (ii) all sediments were modified by hydrodynamics in near‐shore and beach environments; and (iii) fragments of infaunal, beach‐dwelling bivalves were added to the sediment at the strandline. Extraclasts should be expected in older Pleistocene and Cenozoic heterozoan deposits, because the limestones are poorly lithified, largely due to the lack of meteoric cementation, and so easily eroded. Thus, cool‐water aeolianites ought to contain more extraclasts than their warm‐water, tropical cousins. Seagrasses in temperate environments are more productive than in the tropics and thus potentially might contribute many more particles to the beach and dunes than do tropical systems. Although particle breakage in the surf zone cannot be proven, herein the abundance of whole benthic foraminifera and delicate bryozoans implies that suspension and flotsam shoreward transport was an essential process. The similarity of Pleistocene aeolianites over such a long time period herein suggests that the combination of postulated sedimentological, biogenic and hydrodynamic processes could be universally important.  相似文献   

11.
Chukotka is a key region for understanding both Quaternary environmental history and transcontinental migrations of flora and fauna during the Pleistocene as it lies at the far eastern edge of Asia bordering the Bering Sea. The now submerged land bridge is the least understood region of Beringia yet the most critical to understanding migrations between the Old and New Worlds. The insect fauna of the Main River Ledovy Obryv (Ice Bluff) section, which is late Pleistocene in age (MIS 3-2), is markedly different from coeval faunas of areas further to the west, as it is characterized by very few thermophilous steppe elements. From the fauna we reconstruct a steppe-tundra environment and relatively cold conditions; the reconstructed environment was moister than that of typical steppe-tundra described from further west. The data from this locality, if typical of the Chukotka Peninsula as a whole, may indicate that a barrier associated with the environments of the land bridge restricted trans-Beringian migrations, particularly the more thermophilous and xeric-adapted elements of the Beringian biota, supporting the hypothesis of a cool but moist land-bridge filter inferred from evidence from several other studies.  相似文献   

12.
本文讨论了钙质海绵化石主要类别的基本特征,归纳了它们在中国南方二叠纪生物礁中的分布,对于不同地区的钙质海绵动物群进行了综合分析,并在此基础上开展了古生态讨论,初步揭示了钙质海绵在生物礁形成中的作用及其与礁体发育、消亡的相互关系。  相似文献   

13.
This paper reviews the state of our knowledge regarding the effects of the Pleistocene/Holocene transition on the kinds and range of human adaptations in what is now Peru. Following a discussion of geological, paleoclimatic, and archaeological data, the paper focuses upon four aspects of environmental change with specific regard to how these would have affected human adaptations: environmental changes on the Pacific littoral, the extinction of Pleistocene faunal and floral species and their replacement with modern faunas, the adaptive radiation of these modern flora and fauna, especially into the Andean highlands, and characteristics of newly available high elevation environments that would have affected the process by which foraging peoples moved into them. Although Pleistocene fauna have been discovered in Peru, none of these finds have been made in the context of indisputable human activity, and therefore, the effect of their extinction on early foraging peoples is unknown. The earliest acceptable archaeological sites in Peru date around 11–12,000 years ago, and are found on the coastal lowlands. The highlands were not occupied until after 11,000 years ago. While high elevation environments were attractive after 11,000 years ago, they were only slowly occupied by humans due to the constraints of the combined effects of hypoxia and cold.  相似文献   

14.
The paper summarises materials on the mammal remains in northeastern Europe, dated by radiocarbon. Altogether, 23 local faunas of small mammals and 47 local faunas of large mammals were analysed. Multidimensional statistical analysis shows a strong correlation between changes in small mammal fauna composition and climate changes throughout time. The correlations with the spatial gradients, however, are less pronounced. The faunas are classified into three groups: (1) faunas of Holocene age; (2) Late Pleistocene ‘stadial’ assemblages; and (3) Late Pleistocene ‘interstadial’ assemblages. In some cases, changes in species abundance are better understood in terms of biotic interrelations rather than of climatic effects. The most pronounced change in small mammal fauna composition and structure occurred at the Preboreal/Boreal boundary, and a less conspicuous alteration took place at the LGM/Lateglacial transition. The most noticeable transformation in the large mammal fauna composition is dated to the early Holocene. Less significant changes are observed at the Middle Weichselian/LGM transition and at the LGM/Lateglacial transition. It is safely concluded that variations in the faunas of small and large mammals recorded in NE Europe during the last 35 000 years occurred synchronously and unidirectionally.  相似文献   

15.
王乃文 《地球学报》1984,6(3):103-115
<正> 几年前,多数中国地质学家还认为对冈瓦纳研究与中国地质关系不大。虽然新疆早有冈瓦纳型二、三叠纪二齿兽类的发现,人们也只在寻找南、北大陆间的“陆桥”上思考。七十年代中期,北喜马拉雅发现了晚古生代冰海沉积和Stepanoviella冷水生物群以及舌羊齿植物群,这就成了中国冈瓦纳研究的真正开端。但此后许多人仍然认为,在中国只有藏南一隅属于冈瓦纳大陆,雅鲁藏布江—印度河则是南、北大陆的分界。通过近几年中国地质学家以及与法国地质学家的合作研究,发现青藏高原中、北部(拉萨、羌塘地区)与东部(滇西),仍有同时代冰  相似文献   

16.
湖南慈利晚二叠世海绵礁与珊瑚礁的古生态研究   总被引:5,自引:0,他引:5       下载免费PDF全文
王永标  徐桂荣 《地球科学》1997,22(2):135-138
中国南方晚二叠世生物礁分布广泛,但绝大多数属于海绵礁,湖南慈利晚二叠世除发育有海绵礁外,还有至今为止发现的世界上发育最好的古代珊瑚礁,而且海绵礁与珊瑚礁在同一条带上连续分布;因此是研究海绵礁与珊瑚礁古生态关系十分理想的场所,通过对慈利晚二叠世海绵礁及珊瑚礁内部造礁生物群落、沉积相特征,礁化演化序列及成岩作用特征等的分析和对比来研究它们之间的生态关系,发现其中的海绵礁为台地边缘礁,而珊瑚礁则应属于岸  相似文献   

17.
Character, Age and Ecology of the Hezheng Biota from Northwestern China   总被引:4,自引:0,他引:4  
1 Introduction In recent years, field works in the Hezheng area resulted in an explosive growth of new knowledge of Chinese mammalian faunas of the Late Cenozoic. A continuous sedimentary sequence from the Oligocene to the Pleistocene is developed and exposed in the Linxia Basin, Gansu Province, which contains a large number of mammal fossils. The Hezheng area comprises almost the whole Hezheng County, the western half of Guanghe County, the southern half of Dongxiang County, Linxia C…  相似文献   

18.
王鑫 《第四纪研究》1997,17(4):327-332
台湾本岛南端的恒春半岛,出露隆起珊瑚礁石灰岩和现代珊瑚礁海岸。隆起珊瑚礁石灰岩在地貌上的表现是多阶的台地。最高的公园面可达海拔300m,依次向下,是海拔约100~160m的笼仔埔面,海拔70~80m的埔顶面以及海拔10~20m的垦丁面。在恒春半岛的西侧,珊瑚礁台地面已经倾斜,因此高度的表现不同。ESR及14C定年表明,抬升的更新世珊瑚礁台地形成于0.5Ma B.P.前后及0.13Ma B.P.两时期;海拔10~20m的全新世珊瑚礁台地约形成于6 000a B.P.的时期。这些证据显示了地质时期里全球变迁的蛛丝马迹。  相似文献   

19.
Pleistocene faunas from south China are difficult to subdivide based on the long temporal ranges of many taxa and a reduced number of genera in comparison to faunas from temperate north China. In south China, the Ailuropoda–Stegodon fauna is a very general one and includes a relatively stable suite of genera that apparently persisted for long periods of time. These attributes have made constraining its time range difficult. Application of electron spin resonance (ESR) dating of tooth enamel constrains the ages well where uranium uptake was minor. Where uranium uptake into teeth was significant, an approach combining ESR and 230Th/234U isotopic analysis also yields excellent ages. Previous estimates of early, middle and late Pleistocene time ranges previously determined by biostratigraphic seriation for the Ailuropoda–Stegodon fauna are confirmed in all cases but are made more precise with our approach, including specific time ranges for certain archaic taxa. Absolute dating also yields an extended time range for Gigantopithecus blacki of 1200 to 310 ka.  相似文献   

20.
New TIMS dates from British sites underpin and extend the growing model of mammalian faunal history during the Late Pleistocene. The sequence of British faunas during the three successive warm phases of MIS 5 presents a challenging model in which the mammal faunas of the first two temperate phases, 5e and 5c is dominated by species of a classically interglacial character, while that of the final phase, sub‐stage 5a, is dominated by bison and reindeer. This we see as the ‘cold fauna’ appearing in Britain during the cool isotope sub‐stage 5b and subsequently isolated by the rising sea level of isotope sub‐stage 5a. All these three faunas are true island faunas. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

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