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1.
Throughout the Cenozoic, the North American mammalian fauna has been enriched by the appearance of new taxa originating on different continents. During most of the Tertiary, the primary source area of these new taxa was Eurasia with dispersal across some version of the Bering Land Bridge. In the late Pliocene (Blancan) ca. 2.5 mya, the creation of the Panamanian Land Bridge permitted the northward dispersal of species of South American origin including ground sloths. One of these sloths was “Glossotherium” chapadmalense, which in turn gave rise to the Pleistocene species Paramylodon harlani. Mammoths first appear in North America at the beginning of the Irvingtonian ca. 1.9 mya. Despite originating on two different continents, the two species are often found together in North American Pleistocene faunas and shared a common habitat. Both of these lineages are commonly interpreted as grazers, indicative of open grassland habitat, and both of these exotic species shared this habitat with North American endemic species such as horses, also interpreted as grazers. Despite their association in North American faunas, mammoths did not disperse into South America and mylodont sloths were unable to disperse into Eurasia. This suggests there were some aspects of their ecology they did not have in common and there existed a limited zone of conditions that permitted them to share common habitat. There is no evidence that the appearance of either species in North America resulted in the extinction of any native species. The question is how these different species, immigrants and endemics, were able to avoid competition, coexist, and become integrated into a single fauna, thus enriching the overall North American Pleistocene fauna. 相似文献
2.
C.R. Harington 《Quaternary Science Reviews》2011,30(17-18):2341-2354
Unglaciated parts of the Yukon constitute one of the most important areas in North America for yielding Pleistocene vertebrate fossils. Nearly 30 vertebrate faunal localities are reviewed spanning a period of about 1.6 Ma (million years ago) to the close of the Pleistocene some 10 000 BP (radiocarbon years before present, taken as 1950). The vertebrate fossils represent at least 8 species of fishes, 1 amphibian, 41 species of birds and 83 species of mammals. Dominant among the large mammals are: steppe bison (Bison priscus), horse (Equus sp.), woolly mammoth (Mammuthus primigenius), and caribou (Rangifer tarandus) – signature species of the Mammoth Steppe fauna (Fig. 1), which was widespread from the British Isles, through northern Europe, and Siberia to Alaska, Yukon and adjacent Northwest Territories. The Yukon faunas extend from Herschel Island in the north to Revenue Creek in the south and from the Alaskan border in the west to Ketza River in the east. The Yukon holds evidence of the earliest-known people in North America. Artifacts made from bison, mammoth and caribou bones from Bluefish Caves, Old Crow Basin and Dawson City areas show that people had a substantial knowledge of making and using bone tools at least by 25 000 BP, and possibly as early as 40 000 BP. A suggested chronological sequence of Yukon Pleistocene vertebrates (Table 1) facilitates comparison of selected faunas and indicates the known duration of various taxa. 相似文献
3.
过去认为涝池河—阳郭动物群的时代相当或稍晚于泥河湾动物群,早于公王岭动物群,厚镇涝池河动物群的时代与公王岭动物群的一致。但各动物群的层位及在动物群演化上所处的位置表明涝池河—阳郭动物群的时代应与公王岭动物群的一致,比泥河湾动物群的晚,而厚镇涝池河动物群的时代应与陈家窝动物群的相当。重新厘定了公王岭期与陈家窝期的涵义,认为蓝田黄土地层中、早更新统的界线应划在Ｓ８与Ｌ９交界处。 相似文献
4.
We sampled 150 sites in fine-grained Plio-Pleistocene sediments of the Palm Springs and Imperial Formations. Sampling was confined to 3000 m of stratigraphically continuous section containing abundant vertebrate fossil remains of the Vallecito Creek, Arroyo Seco, and Layer Cake local faunas of the Irvingtonian and Blancan Land Mammal Ages. The magnetic stability of these sediments was sufficient to delineate the magnetic stratigraphy, which ranges from below the Cochiti event at the base, to the Matuyama reversed magnetic epoch at the top of the section. Eight faunal events are placed relative to the magnetic polarity sequence. They are cf. Pliohippus extinction, Geomys appearance, cf. Equus appearance, Tremarctos appearance, Hypolagus extinction, cf. Odocoileus appearance, Smilodon and ? Euceratherium appearance. The latter two faunal events characterize Irvingtonian Land Mammal Age. The transition from the Blancan to Irvingtonian Land Mammal Age occurs in the lower Matuyama magnetic epoch close to the Pliocene-Pleistocene boundary. The appearance of European migrants during the lower Matuyama magnetic epoch indicates that the Bering land bridge was exposed for animal migration between Europe and North America at this time. 相似文献
5.
ROBERT G. DUNDAS 《Boreas: An International Journal of Quaternary Research》1999,28(3):375-385
The dire wolf was an important large, late Pleistocene predator in North and South America, well adapted to preying on megaherbivores. Geographically widespread, Canis dirus is reported from 136 localities in North America from Alberta, Canada, southward and from three localities in South America (Muaco, Venezuela; Talara, Peru; and Tarija, Bolivia). The species lived in a variety of environments, from forested mountains to open grasslands and plains ranging in elevation from sea level to 2255 m (7400 feet). Canis dirus is assigned to the Rancholabrean land mammal age of North America and the Lujanian land mammal age of South America and was among the many large carnivores and megaherbivores that became extinct in North and South America near the end of the Pleistocene Epoch. 相似文献
6.
Mammoth fossils and other Pleistocene vertebrates from the Upper Missouri Basin, in the northern Plains and Rocky Mountains of the western interior of North America, have been dated to the late Pleistocene and are associated with Wisconsinan deposits. Mammoth remains have also been found in older stratigraphic contexts. For example, Mammuthus columbi and other fossils from the Doeden Locality are in pre-Wisconsinan terrace gravels along the Yellowstone River; the deposits are likely Illinoian or Sangamonian. Faunas that appear to be associated with the Wisconsinan interstadial, before the Last Glacial Maximum, are found in intermountain valleys and mountain settings (the Merrell Locality, Blacktail Cave, Natural Trap Cave) and on the Plains in both glaciated and unglaciated regions (Box Creek, Wibaux gravel pit). Localities containing faunas dated to the time interval from about the Last Glacial Maximum to the end of the Younger Dryas chronozone (late Wisconsinan) include the youngest fossil-bearing strata at Merrell, Blacktail Cave, Natural Trap Cave; deposits at Sheep Rock Spring, Indian Creek, MacHaffie, False Cougar Cave, Shield Trap Cave; and mammoths found at Sun River, Glendive, Colby, and the Deer Creek drainage. 相似文献
7.
Timing of the Nihewan formation and faunas 总被引：2，自引：0，他引：2
Magnetostratigraphic dating of the fluvio-lacustrine sequence in the Nihewan Basin, North China, has permitted the precise timing of the basin infilling and associated Nihewan mammalian faunas. The combined evidence of new paleomagnetic findings from the Hongya and Huabaogou sections of the eastern Nihewan Basin and previously published magnetochronological data suggests that the Nihewan Formation records the tectono-sedimentary processes of the Plio-Pleistocene Nihewan Basin and that the Nihewan faunas can be placed between the Matuyama-Brunhes geomagnetic reversal and the onset of the Olduvai subchron (0.78-1.95 Ma). The onset and termination of the basin deposition occurred just prior to the Gauss-Matuyama geomagnetic reversal and during the period from the last interglaciation to the late last glaciation, respectively, suggesting that the Nihewan Formation is of Late Pliocene to late Pleistocene age. The Nihewan faunas, comprising a series of mammalian faunas (such as Maliang, Donggutuo, Xiaochangliang, Banshan, Majuangou, Huabaogou, Xiashagou, Danangou and Dongyaozitou), are suggested to span a time range of about 0.8-2.0 Ma. The combination of our new and previously published magnetostratigraphy has significantly refined the chronology of the terrestrial Nihewan Formation and faunas. 相似文献
8.
Mammoths in our midst: The proboscideans of Anza-Borrego Desert State Park®, Southern California,USA
Anza-Borrego Desert State Park® (ABDSP) has an exceptional proboscidean fossil record. The remains of Gomphotheriidae and Elephantidae span over 10 Ma and encompass over eighty productive sites. The most numerous of the proboscideans are the mammoths. Significant specimens include one of the youngest Gomphotherium and the most complete skeleton of Mammuthus meridionalis in North America.Over 6 km of fossiliferous sediments spans the Miocene–Pliocene and Pliocene–Pleistocene boundaries and provides a continuous record of changing environments. Over 550 taxa of aquatic and terrestrial plants, marine and lacustrine invertebrates, and marine, fresh water and terrestrial vertebrates are represented. Present are both Asian and South American immigrant mammals. M. meridionalis and M. columbi (=M. imperator) regionally co-existed here. A specimen from the Diablo Formation extends the temporal range of Gomphotherium in North America nearly one million years into the middle Blancan. 相似文献
9.
John A. Westgate G. William Pearce Shari J. Preece Charles E. Schweger Richard E. Morlan Nicholas J.G. Pearce T. William Perkins 《Quaternary Research》2013,79(1):75-85
Alluvial and lacustrine sediments exposed beneath late Pleistocene glaciolacustrine silt and clay at two sites along the Old Crow River, northern Yukon Territory, are rich in fossils and contain tephra beds. Surprise Creek tephra (SZt) occurs in the lower part of the alluvial sequence at CRH47 and Little Timber tephra (LTt) is present near the base of the exposure at CRH94. Surprise Creek tephra has a glass fission-track age of 0.17 ± 0.07 Ma and Little Timber tephra is 1.37 ± 0.12 Ma. All sediments at CRH47 have a normal remanent magnetic polarity and those near LTt at CRH94 have a reversed polarity — in agreement with the geomagnetic time scale. Small mammal remains from sediments near LTt support an Early Pleistocene age but the chronology is not so clear at CRH47 because of the large error associated with the SZt age determination. Tephrochronological and paleomagnetic considerations point to an MIS 7 age for the interglacial beds just below SZt at CRH47 and at Chester Bluffs in east-central Alaska, but mammalian fossils recovered from sediments close to SZt suggest a late Irvingtonian age, therefore older than MIS 7. Further studies are needed to resolve this problem. 相似文献
10.
Diego Brandoni Raúl I. Vezzosi 《Boreas: An International Journal of Quaternary Research》2019,48(4):879-890
The aim of this contribution is to describe a femur (MCRS 199) assigned to Nothrotheriops sp. from the Late Pleistocene of Santa Fe Province (Argentina), and discuss the implications of this find in the context of the dispersal of ground sloths during the Great American Biotic Interchange. The specimen MCRS 199 is smaller than the femora referred to the North American species Nothrotheriops texanus and Nothrotheriops shastensis but shares several features with these species: (i) shape and position of the greater trochanter, (ii) development of the lesser trochanter, (iii) presence of connection between the third trochanter and the ectepicondyle, (iv) distal third of the femur wider, with ML/DW index of 1.93, and (v) location and relationship of the distal condyles. These similarities allow us to assign MCRS 199 to Nothrotheriops sp. The record of Nothrotheriops sp. from Santa Fe Province chronologically coincides with the earliest records of Nothrotheriops shastensis suggesting a broad geographical distribution of Nothrotheriops during the Late Pleistocene, ranging from 33–36°N (e.g. states of California and Arizona, USA) to 31°S (northern Salado River, Santa Fe Province, Argentina). Thus, Nothrotheriops have dispersed from North America (where Nothrotheriops has early records, Calabrian–Middle Pleistocene) to South America where localities bearing Nothrotheriops are Late Pleistocene in age. In addition, once in South America and probably during the Middle Pleistocene, Nothrotheriops probably gave rise to its sister taxon, Nothrotherium, with records from the Middle Pleistocene (e.g. 223 ka BP, northeastern Brazil) to the Late Pleistocene (e.g. 15 ka BP). 相似文献
11.
基于TM遥感图像解译和野外调研，分析了攀西地区大渡河、安宁河深切河谷地貌特征和断裂带构造变形特征，建立了安宁河断裂带晚新生代5阶段变形历史。研究表明，中新世晚期—上新世早期，安宁河断裂以挤压走滑活动为主；上新世晚期至早更新世时期，断裂以斜张走滑活动为主，活动强度较弱；早中更新世之间发生的元谋运动使昔格达组湖相地层褶皱变形；中晚更新世时期发生断陷作用，形成安宁河两堑夹—垒的构造格局；晚更新世—全新世时期又以左旋走滑活动为主。综合安宁河、大渡河河谷地貌和晚新生代地层记录和变形特征，提出了攀西高原晚新生代4阶段隆升模式：中新世早中期(12Ma之前)以缓慢隆升与区域夷平化作用为主，中新世晚期—上新世早期(12～3．4Ma)是高原快速隆升与河流强烈下切的时期，上新世晚期—早更新世(3．4～1.1Ma)为昔格达湖盆发育时期，中晚更新世—全新世(1．1Ma以来)是高原快速隆升与河谷阶地发育时期。最后指出，至上新世晚期(3．4Ma以前)，攀西高原海拔高度可能超过了3000m。 相似文献
12.
类Ｇａｌｏｗａｙｉｎｅｌａ长期以来被当作长兴阶的带化石，是长兴阶底界的标志。江西上高七宝山剖面表明Ｇａｌｏｗａｙｉｎｅｌａ富集层并非像以往认为的那样是稳定的一层，在此剖面上至少有二层：下层在Ｃｌａｒｋｉｎａｌｅｖｅｎｉ带之下，其上下均有典型的吴家坪期的菊石（Ｋｏｎｇｌｉｎｇｉｔｅｓ等）；上层与吴家坪期的牙形刺Ｃｌａｒｋｉｎａｏｒｉｅｎｔａｌｉｓ，Ｃ．ｇｕａｎｇｙｕａｎｅｎｓｉｓ，Ｃ．ｄｅｍｉｃｏｒｎｉｓ，Ｃ．ｌｉａｎｇｓｈａｎｅｎｓｉｓ共存。这一事实表明Ｇａｌｏｗａｙｉｎｅｌａｍｅｉｔｉｅｎｅｎｓｉｓ是吴家坪期的而不是长兴期的。为此建议，长兴阶的底界不用类定义，而以牙形刺Ｃｌａｒｋｉｎａｓｕｂｃａｒｉｎａｔａ和／或Ｃ．ｗａｎｇｉ的首次出现为准。 相似文献
13.
临汾盆地位于华北克拉通汾渭地堑系中南部,是典型的受控于北东-南西向和近东西向正断层的晚新生代断陷盆地。沉积相、古水流和重矿物综合分析表明,盆地中部的柴庄新生界剖面除顶部的风成黄土之外,可以划分为3个岩性段,分别具有不同的物源,反映了不同时期的构造背景。第一岩性段为上新统（5.0~2.6 Ma）,冲积扇和风成红黏土沉积,冲积扇碎屑物源为盆地周缘的灰岩等沉积岩类;第二岩性段为更新统下部（2.6~1.0 Ma）,三角洲相沉积,沉积物来自盆地南缘中条山北部和东缘太行山西部的太古宇-下元古界的花岗片麻岩和片麻岩、上元古界-古生界的碳酸盐岩、中生界的陆源碎屑岩及少量不同时代的花岗岩;第三段为更新统中上部（ < 1.0 Ma）,河流相沉积,主要物源为盆地北东缘太行山的花岗岩类、少量沉积岩和变质岩。结合区域应力演化过程认为,距今5.0~2.6 Ma期间,受北西-南东向伸展作用影响,北东-南西向正断层为盆地的主控断层;距今2.6~1.0 Ma时期,主要受到北东-南西伸展应力的影响,近东西向断层开始活动;距今1.0 Ma以来,沉积环境由三角洲和湖泊相转为河流相沉积,指示盆地发育的减弱,可能与后一期伸展应力的减弱有关。上述结果表明,受青藏高原向北东扩展的影响,汾渭地堑系至少经历了中新世晚期-上新世早期（>5 Ma）、2.6 Ma和1.0 Ma等主要构造转换时代。 相似文献
14.
研究伊洛瓦底江水系的发育历史对理解青藏高原东南缘的生长具有重要意义,但是长期以来对其形成时代的研究一直比较薄弱。通过研究伊洛瓦底江上游支流的演化可为认识其水系的发育提供重要线索。龙川江是伊洛瓦底江的一级支流,发源于高黎贡山,流经腾冲芒棒盆地。研究表明在上新世时期芒棒盆地曾被一中型湖泊所占据,现代意义上的龙川江并不存在。龙川江在芒棒盆地内同时切割了上新世中晚期和早更新世的火山岩,腾冲地区早更新世火山岩的K-Ar年龄为0.84~1.4 Ma,说明现代龙川江的出现可能不会早于0.80 Ma,由此推测伊洛瓦底江上游水系可能也是0.80 Ma以来形成的。晚新生代以来东喜马拉雅构造结的强烈构造活动可能是其水系形成与演化的动力来源。 相似文献
15.
M.R. Voorhies 《Quaternary Research》1974,4(1):85-93
Pleistocene alluvium along Little Kettle Creek in east-central Georgia contains a unique record of vertebrate life in the Appalachian Piedmont during a colder phase of the late Quaternary. The small fauna includes fishes and the following mammals: Synaptomys cooperi, the southern bog lemming; Clethrionomys sp., a redback vole; Mammut americanum, the American mastodon; a mammoth, Mammuthus sp.; Odocoileus cf. virginianus, a deer; and Bison sp. Both Synaptomys and Clethrionomys are primarily boreal genera of rodents which today reach their southern limits at higher elevations in the Great Smoky Mountains about 175 km north of the fossil locality. The American mastodon is also commonly associated with Pleistocene spruce bogs in eastern North America. Catfish (Ictalurus (?) sp.) vertebrae from the deposit show well-defined annual rings in contrast with the weakly marked annuli produced by fish living in the same area today. The total aspect of the fauna is one of considerably lower temperatures than those prevailing in the Georgia Piedmont now. The joint occurrence of bison and proboscideans indicates an age no older and no younger than late Pleistocene (Rancholabrean) for the assemblage. Because no pollen was found in the sediments and there was insufficient organic matter present for 14C dating, no more precise age can yet be assigned to the fauna. 相似文献
16.
Two mammoth sites from the central Great Plains of North America, each containing one adult Columbian mammoth (Mammuthus columbi), were excavated from Last Glacial Maximum (LGM) loess and fine-grained alluvial deposits, respectively. Taphonomic data from both sites indicate that the mammoth skeletons exhibit numerous spirally fractured limb elements. Dynamic loading points are present on midshafts of large limb bones. Bone flakes produced from the partial thickness of thick cortical bone are also present. Hypotheses of carnivore activity, mammoth trampling, and human-induced fracturing are evaluated as possible causes of the fractured limb bone. Testing the hypotheses using modern data from actualistic taphonomic studies of elephant skeletons, paleontological data from two proboscidean natural death sites, experimental data from elephant bone fracturing, and archaeologically derived data concerning late Pleistocene human modification of mammoth limb bone indicates that the first two hypotheses can be rejected, while the third hypothesis is supported. 相似文献
17.
During the late Pleistocene and early Holocene, Bison was widely dispersed across North America and occupied most regions not covered by ice sheets. A dietary study on Bison paleopopulations from Alaska, New Mexico, Florida, and Texas was performed using two methods that relate dental wear patterns to diet, mesowear analysis and microwear analysis. These data were compared to a mixed sample of extant Bison from the North American central plains, extant wood Bison from Alberta (Canada) and a variety of other modern ungulates. Mesowear relates macroscopic molar facet shape to levels of dietary abrasion. The mesowear signature observed on fossil Bison differs significantly from the hyper-abrasive grazing diet of extant Bison. Tooth microwear examines wear on the surface of enamel at a microscopic scale. The microwear signal of fossil samples resembles to modern Bison, but the fossil samples show a greater diversity of features, suggesting that fossil Bison populations regularly consumed food items that are texturally inconsistent with the short-grass diet typical of modern plains Bison. Mesowear and microwear signals of fossil Bison samples most closely resemble a variety of typical mixed feeding ungulates, all with diets that are substantially less abrasive than what is typical for modern plains Bison. Furthermore, statistical tests suggest significant differences between the microwear signatures of the fossil samples, thus revealing geographic variability in Pleistocene Bison diets. This study reveals that fossils are of value in developing an understanding of the dietary breadth and ecological versatility of species that, in recent times, are rare, endangered, and occupy only a small remnant of their former ranges. 相似文献
18.
中国北方晚更新世哺乳类动物群的划分及其地理分布 总被引：3，自引：0，他引：3
<正> 新第三纪以来,由于青藏高原、喜马拉雅山脉与西部山脉的隆起,我国形成了西高东低的地形特点,导致了气候和环境的变迁,明显地影响了中国哺乳动物的分布。在晚更新世,中国南北动物群分化逐渐扩大,动物群更替尤为频繁。中国晚更新世地层及动物群的研究已有一段相当长的历史,发现了众多重要的遗址和化石地点,积累了丰富的资料。笔者综合有关资料,对我国北方晚更新世动物群,特别是猛犸象-披毛犀动物群的划分、地 相似文献
19.
20.
Alfredo E. Zurita Alfredo A. Carlini David Gillette Rodolfo Sánchez 《Journal of South American Earth Sciences》2011,31(2-3):178-185
Knowledge of the main aspects of the Great American Biotic Interchange (GABI) concerning the glyptodontine Glyptodontidae (Xenarthra) is very scarce. A bidirectional dispersal process was recently proposed for this clade, with the presence of the North American genus Glyptotherium Osborn recognized in latest Pleistocene sediments of northern South America (Venezuela and Brazil). However, the earliest stages of this paleobiogeographical process remain poorly understood, mainly because of the limited fossil record on this clade in late Pliocene sediments. The goals of this contribution are: a) to present and describe the first record of a glyptodontine glyptodontid from the late Pliocene of northern South America, tentatively assigned to a new species of Boreostemma Carlini et al. (Boreostemma? sp. nov); and b) to analyze its paleobiogeographical implications with respect to the GABI. This new material was recovered from the San Gregorio Formation (late Pliocene, prior the GABI) in northern Venezuela, where it is represented by several osteoderms of the dorsal carapace. A comparison among the three known late Pliocene glyptodontine glyptodontids of a) southern South America (Paraglyptodon), b) northern South America (Boreostemma), and c) southern North America ("Glyptotherium"), reveals a series of shared characters between (b) and (c), not present in (a). The most important of these shared characters in (b) and (c) are: all the osteoderms present a great development of the central figure, which is always larger than the peripherals; the sulcus that delimits the central and peripheral figures is narrower and shallower; and all the osteoderms present are relatively thin. This evidence suggests that the lineage of Glyptodontinae which participated in the GABI and subsequently diversified in North America originated in northern South America. Moreover, the evident morphological differences between these glyptodontines with respect to the southern South American forms show a significant separation of both lineages since at least latest Miocene-early Pliocene. 相似文献