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61.
岩亮洞是广西扶绥地区最近新发现的早更新世巨猿化石点,经过初步发掘,采集到了丰富的巨猿材料及大量伴生的哺乳动物化石。引人注目的是其中犀类化石居多,包括146颗完整的牙齿及十多件头后骨骼化石,从形态特征判断,这些犀类化石应属于独角犀的一新种Rhinoceros fusuiensis。岩亮洞巨猿动物群中的独角犀以种群丰度最大而不同于其他已知东亚地区的巨猿动物群中的独角犀类材料。本文从犀类牙齿的主尖釉质层、齿质暴露程度、咀嚼面的磨蚀程度等方面对岩亮洞独角犀的年龄结构进行了研究。该死亡群中至少有4头幼年个体、5头青年个体、5头成年个体和1头老年个体。依据牙齿磨蚀程度和牙齿萌出顺序对年龄结构的分析及统计显示,其中青年个体和成年个体最多,幼年个体次之,老年个体最少,其死亡的原因不是通常意义上磨耗型死亡,突发性的灾害可能是造成这种死亡年龄分布的主要原因。  相似文献   
62.
Reproductive behaviors related to habitat utilization were studied in males of the damsefly,Mnais nawai, which has two male forms, territorial orange-winged males (nawai) and non-territorial pale-orange-winged males (sahoi), at the upper part of a mountain stream where they partiallycoexist with a related species,Mnais pruinosa, which also has two male forms, territorial orange-winged males (esakii) and non-territorial hyaline-winged males (strigata). These two species showed parapatric distribution; the lower part of the stream was occupied byM. nawai, and the upper part byM. pruinosa. In the present study, cross-matings occurred between bothMnais species, although normal intraspecific matings occurred more frequently than cross-matings. Territorial males of both species copulated with conspecific females that entered their territory and guarded the ovipositing females, probably to avoid sperm displacement resulting from subsequent copulations. Severe competition for oviposition sites by territorial males even occurred between the two species. On the other hand, non-territorial males of both species have alternative mating strategies (including several tactics such as sneaking, takeover and interception). The possible benefits from conflict among territorial males of both species is discussed.  相似文献   
63.
 A cytoplasmic male-sterility system has been developed in mustard (Brassica juncea) following repeated backcrossings of the somatic hybrid Moricandia arvensis (2n=28, MM)+B. juncea (2n=36, AABB), carrying mitochondria and chloroplasts from M. arvensis, to Brassica juncea. Cytoplasmic male-sterile (CMS) plants are similar to normal B. juncea; however, the leaves exhibit severe chlorosis resulting in delayed flowering. Flowers are normal with slender, non-dehiscent anthers and excellent nectaries. CMS plants show regular meiosis with pollen degeneration occurring during microsporogenesis. Female fertility was normal. Genetic information for fertility restoration was introgressed following the development of a M. arvensis monosomic addition line on CMS B. juncea. The additional chromosome paired allosyndetically with one of the B. juncea bivalents and allowed introgression. The putative restorer plant also exhibited severe chlorosis similar to CMS plants but possessed 89% and 73% pollen and seed fertility, respectively, which subsequently increased to 96% and 87% in the selfed progeny. The progeny of the cross of CMS line with the restorer line MJR-15, segregated into 1 fertile : 1 sterile. The CMS (Moricandia) B. juncea, the restorer (MJR-15), and fertility restored F1 plants possess similar cytoplasmic organellar genomes as revealed by ‘Southern’ analysis. Received: 17 September 1997 / Accepted: 18 February 1998  相似文献   
64.
湘西北志留纪胴甲鱼化石   总被引:4,自引:2,他引:4  
本文记述了采自湘西北澧县石门水库附近秀山组上段隶属云南鱼目的 Shimenolepis graniferus gen. et sp. nov. 和 QuJinolepidae gen. et sp. indet. 化石,对含鱼层的时代也进行了讨论.  相似文献   
65.
As an infectious disease, tuberculosis (TB) is one of the major causes of death worldwide. Paleopathological and paleomicrobiological studies indicate a long standing association of the causative agent Mycobacterium tuberculosis and its human host. Since the occurrence and the epidemic spread of this pathogen seem to be closely linked to social and biological factors, it is of particular interest to understand better the role of TB during periods of social and nutritional change such as the Neolithic. In this study, 118 individuals from three sites in Saxony‐Anhalt (Germany) dating to the Linear Pottery Culture (5400–4800 BC) were examined macroscopically to identify TB related bone lesions. In two individuals, Pott's disease was detected. In addition, periosteal reactions of varying degrees and frequency were observed mainly along the neck of the ribs in 6.5% (2/31) of subadults and 35.1% (20/57) of adults, with one site standing out markedly. Rib lesions, however, are not specific indicators of TB as they can also be caused by other diseases; so additional investigations were undertaken using histology and micro‐CT scans to say more about the disease process. Supplementary molecular analyses indicate the presence of pathogens belonging to the Mycobacterium tuberculosis complex in individuals of all sites. Furthermore, we discuss the occurrence and spread of TB during the Neolithic with regard to nutritional aspects and possible risks of infection. The data presented provide important insights into the health status of Early Neolithic populations in Central Germany. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   
66.
黔东早—中寒武世凯里组疑源类组合及其界线意义   总被引:13,自引:0,他引:13  
通过对台江八郎和丹寨两条剖面凯里组中疑源类化石的分析,研究,台江剖面产疑源类化石有17属35各(12未定种),其中以Leiosphaeridia,Synsphareidium,Cymatiosphaera,Pterospermella最为丰富,可划分为3个组合,即Cymatiosphaera cf.cristata-Fimbriaglomerella memebrancea组合,Cristallinium-Micrhystridium-Pterospermella组合和Dictyotidium-Granomarginata组合,丹寨平寨剖面凯里组所产疑源类化石有:13属21种(5未定种),同样划分为3个组合,即Leiosphaeridia-Tasmanites组合,Retisphaeridium-Micrhystridium tentatium组合和Baltisphaeridium-Bubomorpha hunjiangensis组合,本文对两条剖面中的凝源类化石的组成,相对含量做了详细的统计,发现在八郎剖面9-2层和平寨剖面3层疑源类的丰度,分异度开始发生明显的变化,表现由早寒武世向中寒武世疑源类组合面貌的转变,这一疑源类转变层位正好是与三叶虫划分的中,下寒武统界线的层位位置相一致,这充分表明疑源类化石可作为划分中,下寒武统的极有价值的微体生物化石证据。  相似文献   
67.
Abstract.— The present study explored phenotypic selection on phenological and morphological reproductive traits in hawkmoth-pollinated Platanthera bifolia (Orchidaceae), a Eurasian perennial herb displaying bisexual, long-spurred flowers. The work was carried out during three flowering seasons (1993–1995) in a Swedish population. Fitness was estimated as the number of pollinia removed (male fitness) and fruits produced (female fitness). Targets and patterns of selection were compared between years and sex functions by the use of multiple linear regression (including correlational selection estimates, i.e., of combination of traits), analysis of covariance, and projection pursuit regression (PPR). Results from the nonparametric surface-fitting-method PPR showed that selection was mostly linear, thus justifying the use of the parametric methods. In all study years, male and female fitness were highest in plants with many flowers. This reflects that flower number sets an upper limit to fitness and that a large inflorescence attracts more pollinators. In 1994, the summer was dry and the average spur length of P. bifolia was shorter than in the other years. In this year, male and female fitness were positively related to spur length, apparently because the spur of short-spurred plants was somewhat too short relative to the tongue length of the local pollinator for optimal pollen export and import. Additionally, the dry weather in 1994 caused a tendency for correlational selection, which was not found in the other years of study. Among small individuals (apparently more sensitive to drought than large ones), early-flowering plants had higher male and female fitness. The results show that patterns of selection may vary both between years and between sex functions in perennial hermaphroditic plants. The present study is one of the first to consider correlational selection in plants, which probably is of common occurrence and deserves to be investigated more.  相似文献   
68.
If a social‐living animal has a long life span, permitting different generations to co‐exist within a social group, as is the case in many primate species, it can be beneficial for a parent to continue to support its weaned offspring to increase the latter's survival and/or reproductive success. Chimpanzees have an even longer period of dependence on their mothers' milk than do humans, and consequently, offspring younger than 4.5–5 years old cannot survive if the mother dies. Most direct maternal investments, such as maternal transportation of infants and sharing of night shelters (beds or nests), end with nutritional weaning. Thus, it had been assumed that a mother's death was no longer critical to the survival of weaned offspring, in contrast to human children, who continue to depend on parental care long after weaning. However, in theory at least, maternal investment in a chimpanzee son after weaning could be beneficial because in chimpanzees' male‐philopatric society, mother and son co‐exist for a long time after the offspring's weaning. Using long‐term demographic data for a wild chimpanzee population in the Mahale Mountains, Tanzania, we show the first empirical evidence that orphaned chimpanzee sons die younger than expected even if they lose their mothers after weaning. This suggests that long‐lasting, but indirect, maternal investment in sons continues several years after weaning and is vital to the survival of the sons. The maternal influence on males in the male‐philopatric societies of hominids may be greater than previously believed. Am J Phys Anthropol, 153:139–143, 2014. © 2013 Wiley Periodicals, Inc.  相似文献   
69.
The placoderm Plourdosteus livonicus (Eastman) (Euarthrodira, Coccosteina) from the Upper Timanian Mikhailovskii Fish Assemblage of the Central Devonian Field is described. The composition and structure of the assemblage are discussed and compared with later Frasnian fish assemblages of the Central Devonian Field.  相似文献   
70.
系统记述了自2001年以来从贵州省毕节扒耳岩洞穴堆积中出土的偶蹄目化石:最后"双齿尖河猪"("Dicoryphochoerus"ultimus)、麂(未定种)(Muntiacus sp.)、凤岐祖鹿(?)(Cervavitus?fenqii)、黑鹿(相似种)(Cervus(R.)cf C.(R.)unicolor)、羚牛(未定种)(Budorcas sp.)、山羊亚科(属种未定)(Caprinae gen.et sp.indet.)、羚羊(未定种)(Gazella sp.)、斯迈提丽牛(未定种)(Leptobos(Smertiobos)sp.)8个种类。毕节扒耳岩巨猿动物群中的偶蹄类与广西柳城巨猿洞和湖北建始龙骨洞的偶蹄类可比性最大。毕节偶蹄类含有较多的古老种类, 指示其地质时代为早更新世早期; 同时显示其生态环境为植被既有密集的丛林又有开阔的草地(或草坡), 局部镶嵌有半开阔树林,而附近分布有一定的水域, 气候温暖, 非常适合高等灵长类栖息。  相似文献   
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