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1.
我国东北地区第一个老第三纪哺乳动物群的研究   总被引:8,自引:6,他引:2  
本文记述了在我国东北地区首次发现的老第三纪哺乳动物群——吉林桦甸哺乳动物群。计有食虫目盔猬亚科的中华晓猬(新属、新种)Eochenus sinensis gen. et sp. nov.,桦甸齿鼩猬(新种)Tupaiodon huadianensis sp. nov.,鼩鼱科的吉林蕾鼩(新属、新种)Ernosorex jilinensis gen. et sp. nov.,灵长目始镜亚科的长白亚洲镜猴(新属、新种)Asiomomys changbaicus gen. et sp. nov.和啮齿目先松鼠科的东方争胜鼠(新属、新种)Zelomys orientalis gen. et sp. nov.和纤细争胜鼠(新种)Z. gracilis. sp, nov.等。其中Eochenus可能代表目前已知最原始的盔猬类。Ernosorex可能是鼩鼱类具有原始特征的旁枝。桦甸哺乳动物群与北美尤因他动物群的关系较近,而与欧洲同期不同。表明当时亚洲与北美之间有直接的动物群交流。其中争胜鼠可能由北美迁来,而鼩鼱类可能从亚洲起源,然后迁往北美。桦甸动物群的时代为晚中始新世或晚始新世。当时桦甸盆地为森林沼泽湖泊景观,气候较温暖潮湿。  相似文献   
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Two series of experiments were performed to assess the effects of stimulus velocity on human subjects' perception of the distance traversed by a moving tactile stimulus. In all experiments, constant-velocity stimuli were applied to the dorsal surface of the left forearm; velocities ranging between 1.0 and 256 cm/sec were used. In some experiments the stimuli moved from distal to proximal over the skin, and in others they moved from proximal to distal. The length of skin contacted by the moving stimulus was defined by a plate having an aperture of 4.0 × 0.5 cm.

In the first series of experiments, subjects were required to compare the distance traversed by a test stimulus delivered 2 sec after a standard stimulus, and also to report the on-locus and the off-locus of the brushing stimulus. In the second series of experiments, the subjects rated the perceived distance on the skin using a free-magnitude-estimation procedure. The data from both series of experiments defined the same relationship between stimulus velocity and perceived stimulus distance. More specifically, although the length of skin contacted by the stimulus was the same at all velocities, subjects' estimates of stimulus distance decreased with increasing stimulus velocity. In addition, the function relating estimates of stimulus distance to velocity was flat for velocities between 5 and 20 cm/sec, but possessed an appreciable negative slope at lower and higher velocities.

It is interesting that the plateau of the relationship between perceived stimulus distance and velocity occurred within the range of velocities that human subjects employ to scan textured surfaces; it also corresponded precisely with the range of stimulus velocities at which the directional sensitivity of somatosensory cortical neurons and human subjects is optimal.  相似文献   
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峨眉山啮齿类和食虫类秋季相对密度调查   总被引:1,自引:1,他引:0  
2002年9月28日~l0月6日,主要用铗日法对四川峨眉山啮齿类和食虫类进行调查,得出以下结论:被捕的20种中,相对密度较大的为高山姬鼠(Apodemus chevrieri)占26.09%、龙姬鼠(Apdemus draco)占18.26%、长尾姬鼠(Apodemus sylvaticus)占15.65%及四川短尾鼩(Anourosorex squamipes)占l0.43%;在5个典型生境样点中,金顶(15.33%)、雷洞坪(20.99%)和仙峰寺(13.95%)3处的兽类相对密度较大,但清音阁(1.01%)和报国寺(0)二处的相对密度很小,导致其显著差异的具体原因尚不清楚,有待进一步研究。  相似文献   
5.
Analyses of anatomical and DNA sequence data run on a parallel supercomputer that include fossil taxa support the inclusion of tenrecs and golden moles in the Afrotheria, an endemic African clade of placental mammals. According to weighting schemes of morphological and molecular data that maximize congruence, extinct members of the afrotherian crown group include embrithopods, Plesiorycteropus, desmostylians, and the condylarths Hyopsodus, Meniscotherium, and possibly Phenacodus. By influencing the optimization of anatomical characters, molecular data have a large influence on the relationships of several extinct taxa. The inclusion of fossils and morphological data increases support for an elephant-sea cow clade within Paenungulata and identifies ancient, northern elements of a clade whose living members in contrast suggest an historically Gondwanan distribution. In addition, maximally congruent topologies support the position of Afrotheria as well-nested, not basal, within Placentalia. This pattern does not accord with the recent hypothesis that the divergence of placental mammals co-occurred with the tectonic separation of Africa and South America.  相似文献   
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Variation in the forefoot skeleton of small-eared shrews (family Soricidae, genus Cryptotis) has been previously documented, but the paucity of available skeletons for most taxa makes assessment of the degrees of intraspecific and interspecific variation difficult. We used a digital X-ray system to extract images of the forefoot skeleton from 101 dried skins of eight taxa (seven species, including two subspecies of one species) of these shrews. Lengths and widths of each of the four bones of digit III were measured directly from the digital images, and we used these data to quantify variation within and among taxa. Analysis of the images and measurements showed that interspecific variation exceeds intraspecific variation. In fact, most taxa could be distinguished in multivariate and some bivariate plots. Our quantitative data helped us define a number of specific forefoot characters that we subsequently used to hypothesize evolutionary relationships among the taxa using the exhaustive search option in PAUP, a computer program for phylogenetic analysis. The resulting trees generally concur with previously published evolutionary hypotheses for small-eared shrews. Cryptotis meridensis, a taxon not previously examined in recent phylogenies, is rooted at the base of the branch leading to the C. mexicana group of species. The position of this species suggests that the mostly South American C. thomasi group shares an early ancestor with the C. mexicana group.  相似文献   
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In the order Lipotyphla (Insectivora), certain reproductive features differ quite distinctly from the eutherian norms, and are of interest with regard to the evolution of mammalian gamete function and perhaps for questions of lipotyphlan phylogeny. As seen in one or more members of five lipotyphlan families (shrews, moles, hedgehogs, golden moles, tenrecs), these features can involve the configuration of the male tract including the penis, the morphology of the sperm head, the anatomy of the oviduct and the patterns of sperm transport within it, the character of the cumulus oophorus, and the way in which fertilising spermatozoa interact with the eggs. However, the picture is by no means uniform within the order. Reproductive idiosyncrasies occur variously in the different lipotyphlan families, and appear consistently and strikingly in shrews--the group studied most extensively. Compared to the patterns in most Eutheria, the most interesting anomalies in soricids include (a) the regulation of sperm transport to the site of fertilisation by oviduct crypts, whose arrangement can vary even according to species, (b) a circumscribed matrix-free cumulus oophorus that appears essential for fertilisation as the inducer of the acrosome reaction, (c) barbs on the acrosome-reacted sperm head by which it may attach to the zona pellucida. With regard to the bearing such reproductive traits might have on lipotyphlan systematics, the African mouse shrew (Myosorex varius) displays a mix of traits that characterize either crocidurine or soricine shrews, consistent with the proposal that it belongs in a more primitive tribe, Myosoricinae, or subfamily, the Crocidosoricinae, from which the crocidurine and soricine lines probably evolved. Moreover, although elephant shrews are assigned now to a separate order (Macroscelidea), they display several of the unusual reproductive features seen in lipotyphlans, particularly in chrysochlorids and tenrecs. On the other hand, if used as a phylogenetic yardstick, none of the reproductive features described serves to define the Lipotyphla as classically constituted within one order, nor necessarily all the relationships suggested by recent sequencing studies of nuclear and mitochondrial genes.  相似文献   
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1. This study tests a model of the relationship of body mass to reproductive power (the rate of conversion of energy from the environment to an organism's offspring). Specifically tested is the prediction that the regression of life-history variables on body size will change slope and sign about an 'optimum' body mass of 100 g.
2. Life-history data from the mammalian order Insectivora have been collated and analysed using a phylogenetic comparative method to test this prediction.
3. The analyses showed little evidence for significant changes in slope or sign around 100g body mass, or other possible optimal body masses, contradicting the predictions of the model. These findings agree with those of similar analyses on life-history variables of bats.  相似文献   
10.
首次从啮齿类和食虫类动物中分离到森林脑炎病毒   总被引:1,自引:0,他引:1  
1988年,我们从采自云南高黎贡山的卵形硬蜱及患者血液中分离到森林脑炎病毒。1990年,又从该地区10种95只啮齿类中查到森林脑炎病毒抗体;并从社鼠(R.confucianus)、小林姬鼠(A.sylvaticus)和灰腹鼠(R.eha ninus)等8种啮齿类及食虫类中分离到15株病毒,选三株用单克隆抗体进行免疫荧光试验、理化特性、生物学特性及中和试验研究。结果表明,其病毒的抗原性、生物学特性及理化特性与东北株及从卵形硬蜱、患者分离的森林脑炎病毒一致。从啮齿类及食虫类分离到森林脑炎病毒在国内属首次报道。这项研究结果进一步证明,啮食类和食虫类在森林脑炎自然疫源地的保存方面起重要作用。  相似文献   
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