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91.
We present here a study of European Neogene primate occurrences in the context of changing humidity. We studied the differences of primate localities versus non-primate localities by using the mammal communities and the ecomorphological data of the taxa present in the communities. The distribution of primates is influenced by humidity changes during the whole Neogene, and the results suggest that the primates track the changes in humidity through time. The exception to this is the Superfamily Cercopithecoidea which shows a wider range of choices in habitats. All primate localities seem to differ from non-primate localities in that the mammal community structure is more closed habitat oriented, while in non-primate localities the community structure changes towards open-habitat oriented in the late Neogene. The differences in primate and non-primate localities are stronger during the times of deep environmental change, when primates are found in their preferred habitats and non-primate localities have faunas better able to adapt to changing conditions. 相似文献
92.
93.
Socrates J Roussiakis 《Geobios》2002,35(6):699
Some relatively rare carnivore remains from Pikermi are studied. The present specimens include Simocyon primigenius(ROTH and WAGNER, 1854), Promeles palaeatticus(WEITHOFER, 1888), Martes woodwardiPILGRIM, 1931, Felis atticaWAGNER, 1857 and Machairodus giganteus(WAGNER, 1848), as well as some postcranial remains that resemble Enhydriodon? latipesPILGRIM, 1931 and are assigned to Mustelidae gen. et spec. indet. Some of these species were not known until now but from their holotypes as M. woodwardi and E.? latipes. Other species such as F. attica and M. giganteus are better known but from relatively scant material. Since the material of the earlier mentioned species comes from Pikermi, their type locality, it is of especial importance and improves our knowledge for the Pikermi carnivores and their relationships to other species. In some cases where the material comes from ossiferous blocks, the accompanying faunal context is discussed. 相似文献
94.
An isolated, large recurved and finely serrated tooth found associated with the prosauropodEuskelosaurus from the Late Triassic part of the Elliot Formation is described here. It is compared to the Triassic thecodonts and carnivorous
dinosaurs and its possible affinity is discussed. The tooth possibly belongs to a basal theropod and shows some features similar
to the allosauroids. This tooth is of significance, as dinosaur remains except for some footprints and trackways, are poorly
known in the Late Triassic horizons of southern Africa. 相似文献
95.
The taxonomic affinities of the Eppelsheim femur, known as Paidopithex, have been unclear for more than a century. Over the years, due to similarities with Pliopithecus, some authors have considered it a large pliopithecid, while others refer to it as Dryopithecus. The issue could not be resolved, because no definitive Dryopithecus femora were available. With the discovery of the Dryopithecus laietanus skeleton from Can Llobateres (CLl 18800), it has become possible to test the attribution of the Eppelsheim femur to Dryopithecus on the basis of direct morphological and metrical comparisons. By means of allometric techniques, we show that the Eppelsheim and D. laietanus femora fit different hindlimb morphologies with regard to relative length and relative head/neck size, with Paidopithex significantly differing from Dryopithecus, but more closely resembling Pliopithecus. Paidopithex also differs from Dryopithecus in other important aspects, such as its lower neck/shaft angle, lack of elevation of the femoral head above the greater trochanter, more posteriorly oriented lesser trochanter, and proximal shaft diameter thicker anteroposteriorly than mediolaterally. In these features, Paidopithex most closely resembles Pliopithecus in spite of differences in body mass (ca. 22 kg vs. ca. 10 kg, respectively). These features suggest that Paidopithex used a primitive locomotor pattern associated with arboreal quadrupedalism, instead of the more derived pattern displayed by Dryopithecus. Currently available evidence confirms that the attribution of Paidopithex to Dryopithecus can be rejected. Paidopithex could be a large and otherwise unknown pliopithecid, but the possibility cannot be ruled out that it represents a third kind of catarrhine. 相似文献
96.
Non-marine diatoms occur in the Deccan Intertrappean beds (Upper Cretaceous) of Mohgaon-Kalan, Chhindwara District, Madhya Pradesh and Pisdura, Lameta Formation (Upper Cretaceous), Maharashtra, India. This represents the oldest record of non-marine diatoms yet reported and the oldest from the Indian subcontinent. The diatoms were recovered from thin sections of chert and dinosaur coprolites by random fracturing. Solitary forms are the most common but colonial filaments up to five cells were also observed. Based on the morphological characters, the diatoms are identified as Aulacoseira Thwaites. The Lower Cretaceous marine diatom genus Archepyrgus Gersonde and Harwood also resembles Aulacoseira in general morphological characters and it seems that Aulacoseira evolved from Archepyrgus and migrated to the non-marine realm. 相似文献
97.
98.
The pollen and charcoal record of a 1,500-cm-long lake sediment core from Lagoa Nova allows a reconstruction of vegetation, climate and fire history in the Atlantic lowland of southeastern Brazil. Today the potential vegetation of the study region would be dense and tall semi-deciduous forest, related to a dry season of 4 months and 1,250 mm precipitation per year. The lowermost core section of Lagoa Nova is probably of late Glacial age and contains only few, poorly preserved pollen grains, indicating dry environmental conditions. Pollen preservation was good above 1,005-cm core depth. Extrapolating from four radiocarbon dates, this interval represents about the last 10,000 years. During the early Holocene (until about 8,500 b.p.), the landscape was dominated by savanna of the campo cerrado type (open shrub woodland), with frequent trees of Curatella americana and small areas of gallery forests along the drainage system. Savanna fires, probably natural, were frequent at that time. The palaeovegetation pattern is consistent with a long dry season of about 6 months and annual precipitation lower than today. Then, up to about 7,560 b.p., gallery forests expanded in the valleys, reflecting a shorter dry season of about 5 months and somewhat higher annual rainfall. Fire was less frequent during this wetter period. Between about 7,560 and 6,060 b.p., savanna expanded and gallery forests retreated, indicating a return to drier climatic conditions of probably between 5 and 6 months dry season and lower precipitation. Fire was again frequent, but not as frequent as during the early Holocene. During the mid to late Holocene period between about 6,060 and 2,180 b.p., the valleys were covered by semi-deciduous forest, but on the hills cerrado vegetation continued to grow. The dry season was probably around 5 months and rainfall was higher than in the preceding period. During the following period between about 2,810 and 600 b.p., the open cerrado on the hills changed to closed cerrado, reflecting wetter conditions with a shorter dry season than in the previous period. It was only after about 600 b.p. that dense semi-deciduous forests expanded throughout the study region, indicating the start of modern, wet climatic conditions with an annual dry season of about 4 months. Fire was nearly absent during this period. The reconstructed palaeoenvironment from the Lagoa Nova record is similar to that of Lago do Pires, indicating that changes in past vegetation, climate and fire frequency are regionally consistent in southeastern Brazil. 相似文献
99.
Somatic hybrids between Solanum bulbocastanum and potato: a new source of resistance to late blight 总被引:4,自引:0,他引:4
J. P. Helgeson J. D. Pohlman S. Austin G. T. Haberlach S. M. Wielgus D. Ronis L. Zambolim P. Tooley J. M. McGrath R. V. James W. R. Stevenson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(6-7):738-742
Solanum bulbocastanum, a wild, diploid (2n=2x=24) Mexican species, is highly resistant to Phytophthora infestans, the fungus that causes late blight of potato. However this 1 EBN species is virtually impossible to cross directly with
potato. PEG-mediated fusion of leaf cells of S. bulbocastanum PI 245310 and the tetraploid potato line S. tuberosum PI 203900 (2n=4x=48) yielded hexaploid (2n= 6x=72) somatic hybrids that retained the high resistance of the S. bulbocastanum parent. RFLP and RAPD analyses confirmed the hybridity of the materials. Four of the somatic hybrids were crossed with potato
cultivars Katahdin or Atlantic. The BC1 progeny segregated for resistance to the US8 genotype (A-2 mating type) of P. Infestans. Resistant BC1 lines crossed with susceptible cultivars again yielded populations that segregated for resistance to the fungus. In a 1996
field-plot in Wisconsin, to which no fungicide was applied, two of the BC1 lines, from two different somatic hybrids, yielded 1.36 and 1.32 kg/plant under a severe late-blight epidemic. In contrast,
under these same conditions the cultivar Russet Burbank yielded only 0.86 kg/plant. These results indicate that effective
resistance to the late-blight fungus in a sexually incompatible Solanum species can be transferred into potato breeding lines by somatic hybridization and that this resistance can then be further
transmitted into potato breeding lines by sexual crossing.
Received: 27 October 1997 / Accepted: 11 November 1997 相似文献
100.
河南淅川盆地的恐龙蛋 总被引:6,自引:2,他引:4
记述了河南淅川盆地10个地点发现的恐龙蛋化石计6种,分属于4个科6个属.其中新属1个、新种2个。新属、新种滔河扁圆蛋(Placoolithustaohensis)以其特有的壳单元分枝特征成为树枝蛋科的新型分子;另一新种渐川树枝蛋(Dendroolithusxichuanensis)与湖北安陆王店树枝蛋(D.wandianensis)性质相似,两者时代应彼此相当;含滔河扁圆蛋的马家村组下部应与其下含淅川树枝蛋的高沟组划归同一时段为宜,即晚白垩世早期;含副圆形蛋、椭圆形蛋、长形蛋、南雄蛋的马家村组中、上部和其上的寺沟组,时代应属晚白垩世中、晚期。 相似文献