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1.
A well-preserved Macaranga leaf fossil from the middle Miocene Fotan Group of Zhangpu County, Fujian, South-eastern China is examined and described as a new species, Macaranga zhangpuensis Z.X. Wang et B.N. Sun sp. nov. The present fossil species represents the highest latitudinal distribution of a reliable Macaranga fossil in the world, and we present the first Macaranga fossil described with detailed cuticular characteristics from China. Based on the global palaeogeographic distribution of Macaranga, we infer that the genus probably originated during the Oligocene in Africa and spread from Africa to India and then to South Fujian, China, further into the Mariana Islands and finally into the Philippine Islands and Malaysia, leading to its present distribution. In addition, the new leaf material described herein is the first Macaranga fossil record with three leaf tips globally. This finding demonstrates that Macaranga with three leaf tips already existed during the Miocene in Fujian, South China, and it provides new information for understanding climatic changes between the Miocene and the present -day.  相似文献   

2.
Abstract: A large collection of lizard vertebrae from northern Africa represents the oldest unambiguous occurrence of the genus Varanus. The fossils come from late Eocene and early Oligocene freshwater deposits of the Fayum, Egypt, an area noted for many significant primate finds. The recovery and identification of this material indicate that the genus Varanus arose in Africa, before dispersing to Australia and Asia. This dispersal occurred prior to the early to mid‐Miocene, by which time fossil Varanus are known from Australia and Eurasia. Although the dispersal route remains unknown, the lizard material reported here supports the hypothesis that a corridor existed allowing freshwater and terrestrial organisms to cross from Africa to Asia.  相似文献   

3.
An upper incisor and upper and lower cheek teeth of Rhinocerotidae from the Upper Miocene of Nakali in central Kenya are described. Those specimens are identified as Diceros sp. The present study confirms the presence of Diceros in sub-Saharan East Africa during Vallesian as noted by several studies. The present result and the fossil records of Diceros in Africa and Eurasia suggest that Diceros might have migrated to Eurasia from Africa by Vallesian, although more fossil records and detailed phylogenetic analysis of Diceros are needed to discuss this hypothesis.  相似文献   

4.
The living hyena species (spotted, brown, striped and aardwolf) are remnants of a formerly diverse group of more than 80 fossil species, which peaked in diversity in the Late Miocene (about 7–8 Ma). The fossil history indicates an African origin, and morphological and ancient DNA data have confirmed that living spotted hyenas (Crocuta crocuta) of Africa were closely related to extinct Late Pleistocene cave hyenas from Europe and Asia. The current model used to explain the origins of Eurasian cave hyena populations invokes multiple migrations out of Africa between 3.5–0.35 Ma. We used mitochondrial DNA sequences from radiocarbon‐dated Chinese Pleistocene hyena specimens to examine the origin of Asian populations, and temporally calibrate the evolutionary history of spotted hyenas. Our results support a far more recent evolutionary timescale (430–163 kya) and suggest that extinct and living spotted hyena populations originated from a widespread Eurasian population in the Late Pleistocene, which was only subsequently restricted to Africa. We developed statistical tests of the contrasting population models and their fit to the fossil record. Coalescent simulations and Bayes Factor analysis support the new radiocarbon‐calibrated timescale and Eurasian origins model. The new Eurasian biogeographic scenario proposed for the hyena emphasizes the role of the vast steppe grasslands of Eurasia in contrast to models only involving Africa. The new methodology for combining genetic and geological data to test contrasting models of population history will be useful for a wide range of taxa where ancient and historic genetic data are available.  相似文献   

5.
Two new fossil charophyte species from middle Miocene lacustrine deposits of Moneva (Ebro Basin, NE Spain) are described and illustrated. Sphaerochara miocenica nov. sp. is represented by medium sized gyrogonites with a characteristic spheroidal shape and ornamented with numerous small and regularly spaced tubercles arranged along the spiral cells. Several specimens show an unusual carbonate encrusted layer that covers completely or partially the gyrogonite. Psilochara monevaensis nov. sp. is characterized by large gyrogonites, with typical prolate shape and protruding apical poles. A second population of S. miocenica nov. sp. from a distant early upper Miocene lacustrine basin located in the Middle East (Bekaa Valley, Lebanon), identified in a previous study as Sphaerochara sp., is described and illustrated here, allowing the comparison of these distant populations. Ecologically, the associated fauna and facies from both localities suggest that these taxa grew in very shallow athalassic lakes. Interestingly, S. miocenica nov. sp. having a wide geographic distribution in peri-Mediterranean lakes with variable salinity, may become a fossil guide for the Miocene, providing at the same time important palaeoecological information.  相似文献   

6.
Abstract: A rich coral‐associated decapod assemblage is recorded from the ‘Depiru Beds’ of the upper part of the Upper Coralline Limestone (Messinian, Upper Miocene), from the island of Malta. Nineteen species within 17 genera have been discovered, where 14 genera are new for Malta. Four new species are described, namely Micippa annamariae sp. nov., Pilumnus scaber sp. nov., Panopeus muelleri sp. nov. and Herbstia melitense sp. nov. Herbstia melitense sp. nov. constitutes the first record of the genus from the fossil record in the Mediterranean region. This discovery more than doubles the number of known fossil decapod species from Malta. The fossil bivalve Jouannetia (J.) semicaudata Des Moulins, 1830 and the extant decapod Maja goltziana D’Oliveira, 1888, are also recorded for the first time from Malta. Other Neogene coral‐associated decapod assemblages are investigated and correlated with the new assemblage from Malta. The migration of taxa between the Mediterranean region and the Paratethys, particularly during the Lower Badenian (Langhian), is evidenced by the strong affinity of the Maltese decapod assemblage with that of the Middle Miocene Badenian assemblages from Hungary, Poland and Ukraine. Upper Miocene, Messinian assemblages from Spain, Algeria and Morocco are also similar to that from Malta.  相似文献   

7.
Miocene primates from southern Africa are extremely rare. For this reason we wish to place on record several interesting new fossil primate specimens recently recovered from the Miocene sites of Berg Aukas and Harasib in the Otavi Mountain region of northern Namibia. The new finds consist of a virtually complete atlas vertebra from Berg Aukas attributable to the hominoid Otavipithecus namibiensis and two teeth and four postcranial fragments from Harasib referrable to Cercopithecoidea. The atlas vertebra exhibits anatomical characteristics intermediate between those of modern cercopithecoids and hominoids which may be indicative of a transition from pronograde to orthograde postures. The cercopithecoid remains show that the earliest Old World monkeys known from southern Africa were small, approximately the size of vervet monkeys. These new specimens are important because they provide the first evidence relating to possible positional behaviors of Otavipithecus and the earliest fossil record of cercopithecoids from southern Africa. © 1996 Wiley-Liss, Inc.  相似文献   

8.
The subfamily Rhizomyinae is known from the Late Oligocene up to the present. Today this group comprises six species, which live in southern Asia and eastern Africa. Despite the current moderate diversity of the rhizomyines, they had a greater diversification and wider distribution in the past: from Asia, their land of origin, to Africa, which they entered during the Early Miocene. So far 33 fossil species can be referred to this group. A cladistic analysis involving fossil and living species has been carried out. Prokanisamys spp. turned out to be the most basal taxa of the ingroup. This analysis calls into question the monophyly of several genera, and allows the proposal of a phylogenetic definition of the tribes Tachyoryctini and Rhizomyini. It also provides information about the origin of the African rhizomyines and allows inferring multiple dispersal phenomena from Asia to Africa in Early and Late Miocene times.  相似文献   

9.
By combining data from a variety of sources we explore patterns of evolution and speciation in Nucella, a widely studied genus of shallow-water marine neogastropods. We present a hypothesis of phylogenetic relationships for all of the currently recognized species of northern hemisphere Nucella, based on an analysis of 718 base pairs of nucleotide sequence from the mitochondrial cytochrome b gene. The order of appearance of species in the fossil record is congruent with this hypothesis. The topology of the inferred phylogeny of Nucella, coupled with ecological, morphological, and fossil evidence, was used to address three main questions: (1) At what time and by which route was the North Atlantic invaded from the North Pacific compared to prior studies of the trans-Arctic interchange? (2) Do patterns of molecular variation within species corroborate the importance of climatic cycles in driving speciation in north temperate marine animals? (3) Was radiation in the direction of increased or decreased ecological specialization, body size, or vulnerability to predation? Molecular evidence confirmed that the sole North Atlantic species, N. lapillus, arose from a North Pacific ancestor. Biogeographic and paleontological evidence supported the dispersal of Nucella, and perhaps other interchange species, via the Eurasian Arctic. Rather intriguingly, the linkage of N. lapillus to a western as opposed to eastern Pacific clade, and the biogeographic origins of the eastern Pacific species, parallel closely similar patterns observed in another genus of rocky-shore gastropods, Littorina. This congruence, in conjunction with information on the climatic and geographic histories of the region, as well as the geographic arrangement of mtDNA haplotypes within Nucella species, supports a model of speciation in Nucella driven by cycles of climatic amelioration and deterioration that began during the Miocene. Calibrations from the fossil record of Nucella suggest that third position transitions and transversions accrue at a rate of 3–4% and 0.5% respectively per million yr. This supports an early participation by Nucella in the trans-Arctic interchange, as suggested by paleobiogeographic studies. Consistent with the unstable taxonomic history of species of Nucella, we found few nonmolecular traits to be phylogenetically informative. Among North Pacific species, more recently derived species (N. canaliculata and the N. emarginata clade) were more ecologically specialized (narrower diet and habitat range). Consistent with extensive intraspecific variation, shell traits were quite labile evolutionarily: neither overall size nor development of antipredatory traits exhibited consistent evolutionary trends over the history of the genus. Nurse eggs (unfertilized eggs consumed by developing embryos) were an ancestral trait that was lost evolutionarily in the two clades that also exhibited increased body size, suggesting that these two life-history traits may be coupled. The reduced number of chromosomes in N. lapillus is clearly a derived state and is consistent with White's (1978) observations on chromosome evolution in other clades.  相似文献   

10.
Itea is a genus of about 20 species of trees and shrubs that are today native to southeastern North America, eastern Asia, and eastern Africa. In this paper, I review the fossil record of Itea, which is based on four types of fossils: diporate, psilate pollen attributed to Itea or the dispersed pollen genus Iteapollis; carpofossils representing fruits and seeds attributed to Itea europaea; flowers preserved in amber and assigned to Adenanthemum iteoides; and leaf impressions attributed to Itea. The distributions of these fossils indicate that Itea was present in western North America from the early Eocene to Miocene, in eastern North America beginning no later than the early Miocene, and in western Eurasia from the late Eocene to Pliocene. Only one datapoint is known from eastern Asia; it is early Miocene in age. Based on the fossil record, it can be inferred that Itea crossed between continents over both the Bering Land Bridge and North American Land Bridge, and that it reached Africa from Europe via Anatolia. Thus, it is predicted that the sole extant North American species, I. virginica, may be most closely related to the sole extant African species, I. rhamnoides. The potential application of Itea fossils to calibrating phylogenetic trees generated from molecular sequence data is also discussed.  相似文献   

11.
The Ayu, Plecoglossus altivelis, comprising three subspecies, is the only species in the genus Plecoglossus in the family Osmeridae. Here, we describe for the first time the discovery of fossil specimens of P. altivelis from the Upper Miocene sediment of Matsue, Shimane Prefecture, Japan. The fossil individuals are subadult and have comb teeth in the second and third generations. These fossil specimens are clearly similar to the recent P. altivelis, the former’s meristic characters being included in the three recent subspecies. In terms of numbers of pectoral fin rays and vertebrae, the fossil specimens are more similar to the subspecies Plecoglossus altivelis ryukyuensis than the other subspecies, but they also show different dorsal fin shapes and anal fin ray counts. This discovery of fossil P. altivelis indicates the persistence of the species for at least 10 million years, from the Late Miocene to the present.  相似文献   

12.
Fossil records of endemic plants play an important role in recognizing the floristic history of East Asia and thereby facilitate the conservation of plant diversity in the region. However, the fossil record of many extant East Asian endemic genera remains poorly documented thus far. Here, we report an infructescence fossil of an East Asian endemic genus, Sladenia (Sladeniaceae), from the early Miocene of southeastern Yunnan, China. The fossil is characterized by: (i) dichasial cymes; and (ii) flask‐shaped ovary with dense subparallel ribs on the surface extending from the base to the distal end of the united style. It represents the first fossil record of Sladenia in Asia, showing that the genus was established in the region at least by the early Miocene. Given that a much older fossil record of Sladeniaceae has been reported from Africa and the sister group of Sladenia is distributed only in Africa, Sladenia is not likely of East Asian origin. The present endemic status of Sladenia was possibly achieved by regional extirpation in Africa and taking refuge in East Asia. This case thus supports the “Museum” rather than “Cradle” hypothesis for the genesis of high plant species in the flora of East Asia. A comparison of the present fossil with extant Sladenia infructescence shows morphological stasis from the early Miocene to present. Such evolutionary tardiness might have resulted in the reduced fitness of the genus, which further caused its current endangered situation.  相似文献   

13.
Studies of the colonization and spread of invasive species improves our understanding of key concepts in population biology as well as informs control and prevention efforts. The characean green alga Nitellopsis obtusa (starry stonewort) is rare in its native Eurasian range but listed by the United States Geological Survey (USGS) as an aggressive invasive in North America. First documented in North America in 1978 from New York, United States, it has since been reported from numerous inland lakes from Minnesota to Vermont, and from Lake Ontario and inland lakes in southern Ontario, Canada. While the ecological impacts of N. obtusa are not clearly understood in its invasive range, initial results show negative environmental effects. We have discovered a liquid‐preserved herbarium specimen that predates the 1978 records by at least 4 years, and is the first confirmed record of N. obtusa in Québec.  相似文献   

14.
The burbot (Lota lota Linnaeus, 1758) is the only freshwater species from the cod family. Various taxonomic hypotheses were tested against molecular data by sequencing the mitochondrial cytochrome b locus of 120 burbot from 41 populations together with the related species Molva molva (ling) and Brosme brosme (tusk), which represented the other Lotinae genera. Within the genus Lota two distinct phylogroups were observed: one in North America south of the Great Slave Lakes (Lota lota maculosa) and one in Eurasia and the remainder of the Nearctic region (Lota lota lota). The burbot lineage separated 10 Myr BP from the other Lotinae, while the genetic variation within burbot appeared to be approximately 1 Myr old. However, fossil evidence suggested that burbot already existed in the Early Pliocene in Europe, from were it probably colonized North America in the Early Pleistocene. While Nearctic burbot survived climatic oscillations and diverged in several refugia, the Eurasian form became extinct or was reduced to a very small population. In the Late Pleistocene the species recolonized the Palearctic region to establish its present distribution range.  相似文献   

15.
The genus Podogonium HEER (extinct legume), known from many Tertiary localities in whole Europe, is rivised and newly combined: Gleditsia knorrii (HEER) GREGOR concerns the fructifications, Gleditsia lyelliana (HEER) HANTKE the leaves; the latter is divided into two formas: knorrii and lyelliana. A comparison with two one-seeded recent Gleditsia-species (G. aquatica MARSH. — USA and G. heterophylla BUNGE — China) yields following palecological setting for the fossil species: They lived under wet conditions (swamps, river banks, alluvial soils) — not in dry climate as believed formerly, together with deciduous trees. The stratigraphical range is from Lower Miocene to Pliocene, with the main occurence in Middle Miocene times (Upper Helvetian, Tortonian, Sarmatian-Karpatian, Badenian, Sarmatian). The fossil species are important plants in the Upper Freshwater Molasse in Bavaria and the adjacent regions.  相似文献   

16.
A large number of plant macrofossils from several Middle to Upper Miocene localities from Iceland have been studied. The fossil material includes four ferns and fern allies, seven conifers, and about 40 species of flowering plants. Betula islandica and Salix gruberi are described as new species. Coniferous twigs previously ascribed to the genus Sequoia are shown to belong to Cryptomeria based on macro‐morphological and epidermal features. Fossil plants from Iceland are compared with coeval fossil taxa from Europe and North America and with living plants. The main finding is that the Miocene flora of Iceland belongs to a widespread Neogene northern hemispheric floral type including plants whose representatives are restricted to East Asia, North America and to western Eurasia at the present time. Previously inferred conspicuous similarities to North American modern equivalents appear to be misleading. The type of vegetation in four plant‐bearing sedimentary formations from the late Mid Miocene to Late Miocene, the 12 Ma Brjánslækur‐Seljá Formation, the 10 Ma Tröllatunga‐Gautshamar Formation, the 9–8 Ma Skarðsströnd‐Mókollsdalur Formation, and the 7–6 Ma Hreðavatn‐Stafholt Formation, corresponds to a humid temperate broadleaved (deciduous)–coniferous mixed forest dominated by Betulaceae, Fagaceae and Acer. Changes in species composition in the sedimentary formations reflect a shift from warm temperate (Cfa climate) to cool temperate (Cfb climate) conditions from the late Mid Miocene to the latest Miocene. This shift was connected to repeated phases of extinction and colonization. Specifically, one set of thermophilic taxa including Magnolia, Liriodendron, Sassafras and Comptonia went extinct between 12 and 10 Ma, and appears to have been replaced by another set of thermophilic taxa in the 10 Ma formation (Juglandaceae aff. Pterocarya/Cyclocarya, Rhododendron ponticum type). The 9–8 and 7–6 Ma formations are characterized by taxa that migrated to Iceland from Europe, such as Fagus gussonii, Betula cristata and Pterocarya fraxinifolia type. Although there is convincing evidence that plants colonized Iceland both from North America and Europe until 12 Ma, migration in the younger formations (9–8, 7–6 Ma) is suggested to have occurred mainly from Europe. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 149 , 369–417.  相似文献   

17.
轮藻纲植物Lychnothamnus barbatus的化石在西班牙加泰罗尼亚地区比利牛斯山脉东部Cerdanya盆地上中新统(Turolian阶)发现。通过与现生L.barbatus的比较研究,发现两者在藏卵器大小方面存在较大差别,据此建立新亚种Lychnothamnus barbatus ssp.megalicarpus subsp.nov.,其藏卵器的各项特征均与器官属Rhabdochara(Madler)Grambast一致,证实两者为同物异名。Lychnothamnus barbatus在盆地上部湖相沉积层中的大量存在,表明湖盆演化史后期发生过营养状况由富营养化向贫营养化转变的现象。  相似文献   

18.
The Paradiaptominae, a subfamily of the large Diaptomidae family, is a small group of freshwater calanoids of which 24 species in four genera have been described. They are endemic to Africa with the exception of four species, Metadiaptomus asiaticus (Asia and Mongolia), M. gauthieri (Africa and Madagascar), Paradiaptomus greeni (India and Sri Lanka) and Neolovenula alluaudi (Canary Islands, North Africa, Baltic and Mediterranean countries). The North African species Metadiaptomus chevreuxi extends its range into Iraq and Iran. The Paradiaptominae are widely distributed in semi-permanent water bodies in the drier areas of Africa although most individual species have a restricted distribution. Only a few species have the ability to colonise permanent waters and these species are usually located at higher altitudes. The Paradiaptominae have not been recorded from the wet equatorial lowland areas of Africa. It seems likely that they are Gondwanian in origin as evidenced by their distribution (Africa, Madagascar, India and Sri Lanka). Neolovenula alluaudi (Mediterranean) shares morphological characters tenuously linked to the other species in the group and may either have a different origin or have branched off at an early stage in evolution of the group.  相似文献   

19.
Xerinae is the most species-rich subfamily of the Sciuridae (Rodentia). This group of animals has a long complex evolutionary history, which witnessed severe environmental changes. In this paper, a comprehensive approach integrating information from fossil records, morphological, molecular and geographical data of extant species, and events of paleoclimate and paleogeography, were used to explore the evolutionary processes in the Xerinae. Xerinae probably originated in Eurasia around the early Oligocene, and dispersed to Africa via the Africa-Eurasia Land Bridge on two occasions during the Miocene, and subsequently evolved into the Protoxerini and African Xerini. The tribe Marmotini derived from a Eurasian ancestor and thrived in North America. Tamias re-occupied Eurasia in the early Miocene, while the distributions of Marmota and ‘Spermophilus’ genus-groups were restricted to North America at least until the late Miocene. Global cooling and the emergence of grass-dominated ecosystems from 15 Ma are likely to be the main causes for the radiation of Marmotini. The body form of Xerinae displays an allometric mode of evolution, with ground-living taxa, such as Marmota, Cynomys and Xerus notably enlarged, while Tamias has remained slim in body form. To cope with the global environmental changes, particularly the global cooling induced forest degradation and grassland expansion in the late Miocene, most Marmotini developed into true ground squirrels with short tails. The slim body adaptation in Tamias may be related to competition from tree squirrels, or their hoarding behavior, the latter helping them to cope with cold winter.  相似文献   

20.
Aim The role of dispersal versus vicariance for plant distribution patterns has long been disputed. We study the temporal and spatial diversification of Ranunculeae, an almost cosmopolitan tribe comprising 19 genera, to understand the processes that have resulted in the present inter‐continental disjunctions. Location All continents (except Antarctica). Methods Based on phylogenetic analyses of nuclear and chloroplast DNA sequences for 18 genera and 89 species, we develop a temporal–spatial framework for the reconstruction of the biogeographical history of Ranunculeae. To estimate divergence dates, Bayesian uncorrelated rates analyses and four calibration points derived from geological, fossil and external molecular information were applied. Parsimony‐based methods for dispersal–vicariance analysis (diva and Mesquite ) and a maximum likelihood‐based method (Lagrange ) were used for reconstructing ancestral areas. Six areas corresponding to continents were delimited. Results The reconstruction of ancestral areas is congruent in the diva and maximum likelihood‐based analyses for most nodes, but Mesquite reveals equivocal results at deep nodes. Our study suggests a Northern Hemisphere origin for the Ranunculeae in the Eocene and a weakly supported vicariance event between North America and Eurasia. The Eurasian clade diversified between the early Oligocene and the late Miocene, with at least three independent migrations to the Southern Hemisphere. The North American clade diversified in the Miocene and dispersed later to Eurasia, South America and Africa. Main conclusions Ranunculeae diversified between the late Eocene and the late Miocene. During this time period, the main oceanic barriers already existed between continents and thus dispersal is the most likely explanation for the current distribution of the tribe. In the Southern Hemisphere, a vicariance model related to the break‐up of Gondwana is clearly rejected. Dispersals between continents could have occurred via migration over land bridges, such as the Bering Land Bridge, or via long‐distance dispersal.  相似文献   

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