更新世大熊猫牙齿釉质的超微结构

本文应用扫描电镜研究了目前世界上已知的三种大熊猫——大熊猫小种和大熊猫巴氏亚种以及现生大熊猫的牙齿釉质的超微结构.总的看来,从更新世早期的大熊猫小种到现生的大熊猫,其釉柱的变化,是由粗逐渐变细,数量逐渐增多,柱间区的宽度变窄.这可能反映了大熊猫食性不断特化和咀嚼功能逐步加强.从釉柱的形态和排列来看,大熊猫小种与现生大熊猫的亲缘关系,比它与大熊猫巴氏亚种更为密切;由此,大熊猫巴氏亚种可能不是现生大熊猫的直接祖先,进而提示,我国更新世中、晚期的大熊猫非止一个"种"(或亚种).     

环境因子对野化培训大熊猫在生境斑块中行为表现的影响

采用动物行为观察中的聚焦动物法和生境斑块调查的样方法, 调查和分析了2003年7月至2004年9月卧龙自然保护区大熊猫"祥祥"在野化培训圈中的行为表现及其与环境因子的关系.结果 表明:野化培训大熊猫在生境斑块中的行为表现主要以取食为主,占63.14%,其次是移动行为和休息行为,分别为15.85%和8.91%,爬树行为最少,仅0.23%;且不同月份各种行为类型的分配格局具有相似模式,无显著性差异(P=1.0).分析食物分布对大熊猫行为表现的影响,其取食、吃馍和称重、休息以及饮水等行为在有无竹子分布的斑块之间差异显著(P<0.05),而其它行为不甚明显(P>0.05).从生境结构的环境组成因子来看,野化培训大熊猫的行为表现除与斑块个别组成因子具有较为明显的相关关系之外(P<0.05),与其它环境因子均无显著性相关(P>0.05).据此对产生这种结果的原因进行了探讨,并对今后圈养大熊猫的野化培训提出了建议.     

大熊猫的系统地位与种群生态学的研究与进展

大熊猫分类的争论已持续了１３０年。自１９８４～１９８５年Ｏ’Ｂｒｉｅｎ进行蛋白质分子与ＤＮＡ系列的研究后,到９０年代,多数西方学者都同意大熊猫隶属于熊科的特点。但在中国,多数学者从生物学的不同学科和水平,尤其在从古生物学方面的研究结果,坚持把大熊猫独立为一科。１９８９年邱占祥等研究了云南中新世大熊猫的祖先化石以后,１９９３年黄万波又研究了大熊猫的颅骨、下颌骨及牙齿,进一步论证早在中新世晚期,始熊猫     

观音山自然保护区和佛坪自然保护区大熊猫种群的分布格局

2007年10月和2008年4月,对佛坪自然保护区和观音山自然保护区内大熊猫的活动痕迹进行了样线调查,研究了该区内大熊猫种群及其同域主要伴生动物的分布情况,并分析了影响大熊猫活动分布格局的环境因素.结果表明：观音山和佛坪自然保护区的大熊猫及同域主要伴生野生动物的分布格局基本一致,大熊猫在观音山自然保护区的活动痕迹密度、范围均小于佛坪自然保护区;研究区内2个大熊猫高密度等级的活动中心均分布在佛坪自然保护区内;观音山自然保护区内的大部分地区无大熊猫活动;羚牛、斑羚、野猪等大熊猫主要伴生动物在观音山自然保护区内的活动痕迹数量高于佛坪保护区;人类干扰可能对大熊猫种群活动的分布格局产生影响.     

大熊猫尸体组织LDH同工酶盘电泳观察

大熊猫是冰川时期残存至今的古老、稀有的珍贵动物,有“活化石”之称。对大熊猫的研究除野外调查(王朗自然保护区大熊猫调查组,1974)、形态解剖(张鹤宇等,1959;冯文和等,1984)、人工饲养繁殖(北京动物园,1974;冯文和等,1983;1984)等外,尚有生化技术和免疫学等研究方法(Sarich,1973;潘文石等,1982;罗昌容等,1984)。     

秦岭巴山木竹微量元素及营养成分分析

竹子是大熊猫(Ailuropoda melanoleuca)的主要食物(胡锦矗等,1985;胡锦矗,2001).巴山木竹(Bashania fargesii)分布广,是秦岭大熊猫主食竹种之一(田星群和刘其建,1985).该竹在秦岭的分布具有明显的水平和垂直地带性,分布中心正好和该山系大熊猫分布中心相吻合(田星群和刘其建,1985).秦岭大熊猫有长达8个月的时间在巴山木竹林中觅食(潘文石等,1988).为揭示食物营养成分对大熊猫觅食行为的影响,深入认识该物种适应竹子这种低营养价值食物的觅食对策,本文以采自陕西省佛坪国家级自然保护区的222份巴山木竹样品为研究对象,分析了7种微量元素及2种营养物质在不同季节、年龄及生长部位的含量,以促进对野生大熊猫生态习性的深入了解,亦能为罔养大熊猫的人工饲养繁殖提供参考.     

野化培训大熊猫采食和人为砍伐对拐棍竹无性系种群更新的影响

亚高山竹类占据着野生大熊猫(Ailuropoda melanoleuca)食物组分的99%,竹子的生命周期与大熊猫的生活史密切相关,竹子的更新和生长直接影响着大熊猫的生存与保护.为了弄清大熊猫的采食利用和人为砍伐是否促进或制约竹子的繁殖更新,应用样方法、定位观察法,连续研究了卧龙自然保护区大熊猫栖息地内野化培训大熊猫采食、人为砍伐和对照样方中拐棍竹无性系种群的更新动态.结果表明,在相同种群数量和环境条件的基础上(p>0.05),被大熊猫采食竹子的比例为67.07%,致死率29.07%;人为砍伐竹子的比例为65.67%,致死率46.68%,可见与大熊猫采食相比,砍伐更为影响拐棍竹种群的生存.从出笋数量来看,不同处理方式有利于拐棍竹无性系种群的更新(p<0.05),尤其是人为砍伐措施大大提高了竹子的出笋率,但人为砍伐样方的竹笋质量(地径和株高生长)却远低于大熊猫采食和对照样方,未能达到大熊猫觅食的选择利用标准.不同年份之间,各种处理方式下的拐棍竹出笋数量波动较大(p=0.006～0.035),并随着恢复时间的延长,逐渐趋于相似(2007,p=0 825).不同处理方式之间,拐棍竹无性系种群的年补充率,各年份均具有显著性差异(p<0.05,除2007年外),年死亡率仅2003年和2004年有明显的差异(p<0.05),2005～2007年均不显著(p>0.05).拐棍竹无性系种群的年补充率与年死亡率之间表现出年补充率﹥年死亡率的格局(p<0.05),唯有大熊猫采食样方的2004年和2005年、人为砍伐和对照样方的2005年的年死亡率略高于年补充率(p>0.05),这表明拐棍竹无性系种群对大熊猫采食和人为砍伐具有无性系整合的补偿效应.     

大熊猫胃肠道中消化酶活力的分析

为了研究大熊猫对食物的化学性消化特点和机制,测定了9只大熊猫唾液和3只大熊猫胃肠道中主要消化酶的活力,并与其他动物进行了比较.结果显示,大熊猫唾液呈碱性,蛋白酶和淀粉酶等消化酶活力低;肠道中淀粉酶活力高,而脂肪酶活力明显低于棕熊.大熊猫小肠粘膜中存在显著量的蔗糖酶、乳糖酶和麦芽糖酶活力.另外,在1只大熊猫胃和直肠液中检测到了少量纤维素酶活力.研究结果提示,大熊猫唾液直接参与食物消化的作用可能很弱;大熊猫对淀粉类食物有很好的消化能力,但对脂肪类食物消化能力相对不高.大熊猫胃肠道消化酶的活力特点适应其消化天然食物中的营养物质.     

应用微卫星标记分析圈养大熊猫遗传多样性

以来源于成都大熊猫繁育研究基地和中国保护大熊猫研究中心的34只圈养大熊猫(分为a群体和b群体)和7只圈养野生大熊猫(圈养野生群)作为研究对象,利用AY161177～AY161218、Ame-μ5～Ame-μ70和g001～g905等30个微卫星标记对其遗传多样性现状进行分析,并探讨保持圈养大熊猫遗传多样性的方法.微卫星数据表明,30个微卫星标记多态性好(PIC=0.621～0.640),圈养大熊猫遗传多样性水平(a群体:A=5.48,Ho=0.475,He=0.696;b群体:A=5.24,Ho=0.453,He=0.719;圈养野生群:A=3.80,Ho=0.514,He=0.725)高于6个濒危物种(Ho=0.210～0.390,He=0.150～0.430)但低于3个非濒危物种(Ho=0.620～0.710),圈养大熊猫遗传多样性水平都保持在较高水平,但圈养群遗传多样性水平与圈养野生群相比有所降低.F统计量及基因流Nm分析结果证明,a、b两群体间遗传分化程度不高(Nm=2.610,Fst=0.0874,Fit=0.4116),存在个体交换和一定程度的近交,b群体近交程度高于a群体(a群体Fis=0.3221,b群体Fis=0.3983).因此,现阶段圈养大熊猫的管理重点是避免近交和遗传多样性丧失,将圈养大熊猫种群作为同一管理单元,把纠正大熊猫系谱中的错误、科学选择大熊猫个体进行群体间交流作为关键点,利用微卫星技术保持和提高大熊猫种群的遗传多样性水平.     

首例大熊猫睾丸精原细胞瘤的病理学诊断

<正>大熊猫(Ailuropoda melanoleuca),是我国濒危珍稀的国家一级保护动物,其疾病的研究与防控受到高度关注。目前在寄生虫疾病、病毒性疾病、细菌性疾病(李玉欢等,2013;杨虎田,2014; Jin et al.,2017)等方面进行了大量研究,对大熊猫保护起到了重要作用。肿瘤作为一种严重影响人类与动物健康的疾病一直是人类医学与动物医学研究的重要内容。目前,报道圈养野生动物肿瘤疾病的文献比例较低(张成林等,2013;曹霞,2019),此类疾病对患病个体伤害极大。近年来,     

Technical note: Occlusal fingerprint analysis: Quantification of tooth wear pattern

Information about food ingestion and mastication behavior during the lifespan of an individual is encoded in the dental occlusal wear pattern. To decode this information, we describe a new method called occlusal fingerprint analysis (OFA). Structural parameters of wear facets on the occlusal surface of teeth are quantified from digitized casts for the interpretation of occlusal aspects. The OFA provides an individual three‐dimensional dental occlusal compass that indicates the major pathways of interaction between antagonists, revealing information about development, spatial position, and enlargement of wear facets. Humans develop a very similar overall pattern of crown contacts, although specific characteristics of wear facets reflect an individual's occlusal relationships and masticatory behavior. We hypothesize that the wear pattern is a unique character and therefore valuable for individual identification. Furthermore we suggest that OFA, when further developed, may be useful for identification of behavioral, biological, and chemical factors affecting crown morphology. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Individual variation in enamel structure of human mandibular first premolars

Nine human mandibular first premolars were examined to assess variation in external morphology and enamel structural organization within a tooth type. The relationship of enamel ultrastructure to gross dental morphology was also studied. The teeth were cut in the mesiodistal direction just lingual to the buccal cusp, and etched. Montages were constructed of the cut enamel surface photographed in the scanning electron microscope at 100 X magnification. Parameters were measured and correlation coefficients were calculated for the comparison of various odontometric features. The mesiodistal and buccolingual dimensions were highly correlated and the occlusal thickness of enamel was significantly correlated to crown height but not crown width. Hunter-Schreger bands were less pronounced in fossa areas than at lateral aspects, cusps, or ridges; these bands were directly related to the geometry of the tooth. It was concluded that within this tooth type, there is a large amount of individual variation not only in gross morphology but also in enamel ultrastructure. This result underscores the fact that interspecific comparisons must be made with care.     

Hominin lower second premolar morphology: evolutionary inferences through geometric morphometric analysis

Mandibular premolars are increasingly used in taxon-specific diagnostic analyses of hominins. Among the principal difficulties in these evaluations is the absence of discrete, discernible, and comparable anatomical structures for rigorous quantitative assessment. Previous research has addressed either internal crown surface features (such as cusps and fossae) or the morphology of the crown outline. In the present paper, we integrate both types of information in the examination of morphological variation of lower P4s (n = 96) among various fossil hominin species with an emphasis on genus Homo. We use a set of 34 2D landmarks combining coordinate data from four classical dental landmarks on the occlusal surface and 30 sliding semilandmarks of the crown outline. Our results indicate that external shape variation is closely related to the configuration of the occlusal morphological features and influenced by dental size. The external and internal shapes of P4 are polymorphic but still useful in depicting a primitive-derived gradient. The primitive pattern seems to have been an asymmetrical contour with a mesially displaced metaconid, development of a bulging talonid, and a broad occlusal polygon. The trend toward dental reduction during the Pleistocene produced different morphological variants with a reduced occlusal polygon and decreased lingual occlusal surface in later Homo species. Homo heidelbergensis/neanderthalensis have fixed plesiomorphic traits in high percentages, whereas in modern humans a symmetrical outline with a centered metaconid and talonid reduction evolved.     

Concepts of occlusion: Australian evidence

Longitudinal studies of aboriginal children over a 20-year period have drawn attention to the wide variation in morphological features of the dentition and the way in which occlusal relationships develop. This paper summarizes some important determinants of optimal occlusal development, namely, tooth size relationships within and between dentitions, the patterns of alveolar growth, and tooth migrations during the transition from primary to permanent teeth and the nature of growth changes in the dental arches. Dental occlusion constantly changes throughout life in response to changing functional requirements. Observations limited to cross-sectional material provide an incomplete, and sometimes misleading, concept of dental occlusion and masticatory function.     

Evolution of anthropoid jaw loading and kinematic patterns

Major transformations in the skull and masticatory system characterized the evolution of crown anthropoids. To offer further insight into the phylogenetic and arguably adaptive significance of specific primate mandibular loading and kinematic patterns, allometric analyses of metric parameters linked to masticatory function are performed within and between 47 strepsirhine and 45 recent anthropoid species. When possible, basal anthropoids are considered. These results are subsequently integrated with prior experimental and morphological work on primate skull form. As compared to strepsirhines, crown anthropoids have a vertically longer ascending ramus linked to a glenoid and condyle positioned relatively higher above the occlusal plane. Interestingly, anthropoids and strepsirhines do not exhibit different mean ratios of condylar to glenoid height, which suggests that both clades are similar in their ability to evenly distribute occlusal contacts and perhaps forces along the postcanine teeth. Thus, given the considerable suborder differences in the scaling of both glenoid and condylar height, we argue that much of this variation in jaw-joint height is linked to suborder differences in relative facial height due in turn to increased encephalization, basicranial flexion, and facial kyphosis in anthropoids. Due to a more elongate ascending ramus, anthropoids evince more vertically oriented masseters than like-sized strepsirhines. Having a relatively longer ramus and a more medially displaced lateral pterygoid plate, crown anthropoids exhibit medial pterygoids oriented similar to those of strepsirhines, but with a variably longer lever arm. As anthropoid masseters are less advantageously placed to effect transverse movements/forces, we argue that balancing-side deep-masseter activity underlying a wishboning loading regime serves to increase, or at least maintain, transverse levels of jaw movement and occlusal force at the end of the masticatory power stroke. Crown anthropoids are also more isognathic and isodontic than strepsirhines. A consideration of early anthropoids suggests that the crown anthropoid masticatory pattern, i.e., more vertical masseters due to a high condyle as well as greater isognathy and isodonty, occurred stepwise during stem anthropoid evolution. This appears to correspond to a more transverse, and perhaps progressively larger, power stroke across oligopithecids, parapithecids, and propliopithecids.     

Skull Shape, Masticatory Apparatus, and Diet of Vassallia and Holmesina (Mammalia: Xenarthra: Pampatheriidae): When Anatomy Constrains Destiny

The form and function of the masticatory apparatus of the fossil genera Vassallia and Holmesina are analyzed so that the possible dietary behaviors of these pampathere xenarthrans might be inferred. Analysis is based on comparisons of dental morphology and skeletal features (through RFTRA) associated with the masticatory musculature among the pampatheres, the extant dasypodids Euphractus and Dasypus, and the glyptodont Propalaeohoplophorus. A method is proposed for generating a moment arm of the massetericus independently of the muscle's line of action, which allows direct comparison among extant and fossil mammals. The masticatory apparatus of the pampatheres strongly resembles that of Euphractus among extant forms, but the development of muscular attachment sites indicates a more powerful musculature, particularly the massetericus; the taxa differ most markedly in dental morphology. Long moment arms about the jaw joint and large ratios of muscle to bite moments indicate forceful rather than quick movements. The various skeletal and dental features analyzed suggest that the masticatory apparatus of the pampatheres was more powerful and efficient in transverse chewing than in dasypodids and that they were primarily grazers consuming mainly coarse vegetation. These features, some shared with herbivorous ungulates, include wide, relatively flat mandibular condyles; condyles well dorsal to muscular insertion sites; expanded angular processes; unfused symphysis; a posteriorly extended tooth row; open-rooted teeth; mesial teeth that bear mainly transverse striations; distal teeth that are mesiodistally elongated, bear basined occlusal surfaces, and in Vassallia possess a central island of resistant dentine that acted as a functional analogue of an ectoloph; and teeth with a stepwise arrangement. The results of this study indicate that detailed analysis and comparison of morphology lead to useful predictions of behavior.     

Hunter-Schreger band orientation in interproximal enamel of modern human molars with complex morphological traits

A recent paper concerning characteristic groove-shaped wear in interproximal attritional facets of Neandertal posterior teeth correlated groove formation with deep enamel structural traits (Villa & Giacobini, 1995). Further studies were carried out on modern human teeth in order to evaluate a possible correlation between deep enamel structure and some crown complex morphological features. Seventy-five isolated molars from medieval and recent ossuaries as well as five molars recently extracted for therapeutic purpose were examined using scanning electron and optic microscope ground sections of interproximal enamel. The results showed possible correlations between deep enamel structural characteristics (i.e., Hunter-Schreger band verticalization) and some crown complex traits (i.e., occlusal groove pattern, mesial and distalfovea, mesial and distal accessory tubercules, interproximal marginal ridges). Observations reported in this study showed a significantly higher frequency of Hunter-Schreger band verticalization in lower molars with an occlusal complex pattern (i.e. primitive fissure pattern “Y” or “+”). This observation suggests a positive correlation among crown complex traits (which occur frequently in Neandertal teeth) with deep enamel structural characteristics. In addition, analysis of teeth grouped according to individual showed crown morphological traits and deep enamel structural characteristics corresponding to the same individual. This observation supports a genetic basis in occlusal shape and microstructural dental traits.     

全新世中国北方人群第一臼齿齿冠面积和齿尖相对面积的测量分析

通过对532枚中国北方地区新石器时代到青铜时代和铁器时代人类上、下颌骨第一臼齿(M1和M1)齿冠面积和齿尖面积的测量和分析, 得到以下关于中国北方近代人群牙齿尺寸的准确数据和变异情况的结果: 两性M1和M1齿冠面积存在显著性差异, 男性齿冠面积大于女性齿冠面积, 齿尖相对面积不存在性别差异; 从新石器时代到青铜时代男性M1和M1分别缩小了1.16%和4.96%, 女性分别缩小了5.68%和6.11%,青铜时代到铁器时代齿冠面积无明显变化; M1颊侧尖相对基底面积大于舌侧尖, 形成齿尖大小差异的原因很可能是在人类演化过程中, 齿冠面积整体缩小的趋势下, 为使咬合面最大化使用, 各齿尖朝着更利于扩大咬合面基底面积的方式进化的结果; 世界各地区近代人群M1和M1各齿尖大小顺序基本一致, 其中M1为原尖>前尖>后尖>次尖, M1下原尖最大, 下次小尖最小, 其他三个齿尖面积非常接近, 不存在明显大小变化。     

Fossil evidence of evolutionary convergence in juvenile dental morphology and upper canine replacement in sabertooth carnivores

The convergent suite of morphological traits characterizing the mammalian sabertooth ecomorphology is well documented, including modifications of the dental and osteological portions of the masticatory apparatus from a less‐specialized carnivore condition. Equally important is how those specialized adult morphologies developed through ontogeny because previous studies have shown that growing such specialized craniodental traits may require evolutionary modification of growth patterns and tooth replacement mechanisms. Despite the understanding of convergent morphological specialization in adult sabertooth carnivores, the possibility of a convergent ontogenetic trajectory toward those adult morphologies has not been rigorously examined. The present study examines numerous previously undescribed juvenile nimravid specimens. The results provide insights about nimravid ontogeny and show, for the first time, that the nimravid sabertooth lineage included species in which the permanent upper canine erupted within a lingual concavity of the deciduous upper canine until it reached comparable crown height beyond the alveolar border. Furthermore, this investigation assesses the juvenile morphology and upper canine replacement of felid and barbourofelid sabertooth taxa. The results provide evidence of convergence in deciduous upper canine morphology of three sabertooth carnivore lineages (i.e., nimravid, felid, and barbourofelid), as well as preliminary evidence of convergence in the upper canine replacement process. It might be beneficial for studies of extreme morphological specialization to simultaneously consider convergence in adult morphologies and how morphologies change through ontogeny.     

A new genus and species of fossil myliobatoid ray from the Fishburne Formation (lower Eocene/Ypresian) of Berkeley County,South Carolina,USA

Elasmobranch fossils recovered from the Fishburne Formation (lower Eocene/Ypresian) of Berkeley County, South Carolina, USA, include species from four genera of sharks and six genera of rays. Of particular interest was the recovery of multiple isolated teeth from a new genus and species of the cownosed ray family Rhinopteridae, which is the focus of this study. The unique crown morphology separates this genus and species from Rhinoptera. Eorhinoptera grabdai, gen. et sp. nov., is represented by small, bar-shaped teeth in the shape of greatly elongated hexagons. These teeth are the isolated elements of a dental plate. The holotype, with 12 wide root lobes, is the most elongated in the sample being 1 cm long and 1.5 mm wide, indicating an origin in the central region of the plate. Paratypes are less elongated, have 4–8 root lobes and are from more lateral rows. The crown is smooth and has a distinctly convex occlusal surface. Eorhinoptera is only the second genus of cow-nosed ray. Its distinctive crown morphology may have allowed it to exploit different kinds of prey than those favoured by rays that lacked convex tooth crowns.