多元分析方法分辨细齿小塔塔鼠的下臼齿

啮齿类梳趾鼠科小塔塔鼠的下臼齿的形态非常接近。本文根据已有的一百多个牙齿,用齿冠的长度和宽度两个性状,在坐标系中画出了M_1、M_2和M_3的一系列椭圆,代表着这些牙齿一定比例的样本分布范围,并以此得出了细齿小塔塔鼠这三种牙齿的判别线。     

周口店新发现的中国猿人化石

1.本文系根据1949年北京解放后迄今在周口店中国猿人化石产地发掘而得的及由过去发现的碎骨中清理而得的中国猿人化石,加以研究,计有单独的牙齿5枚(左上内侧用齿,右上第一及第二前臼齿,左下第一和第二臼哲各1枚),肱骨及胫骨干各一小段,而胫骨化石是在周口店首次发现的新材料。2.中国猿人的牙齿有大小两种头型,大型为男性,小型为女性,本标本中的上门齿,下第一及第二臼齿属大型,所以是男性的,上第一及第二前臼齿属小型,所以是女性的。3.中国猿人的牙齿,无论其齿冠或齿根,都远较现代人或尼安德特人为硕大和粗壮。4.上内侧门齿齿冠舌面的基部有很发达的底结节及由其延伸而来的指状突, 舌面两侧增厚且向内捲而使舌面成为铲形?莞氤莨诘某ぶ嵩谝恢毕呱隙蝗缦执说某莞氤莨诘某ぶ岢梢欢劢恰?.上第一前臼齿的齿冠和齿根都大而粗壮。齿冠的唇面有三角形隆起,但其尖端偏向前方。唇结节较舌结节为大和高,嚼面的唇半大于舌半,具有特殊型式的纹理。齿根极宽,部分分为唇舌两枝。6.上第二前臼齿稍较上第一前臼齿为小,舌结节不如第一前臼齿的倾向前方。唇舌两正中(?)互相连续而将嚼面分为前后两半。唇舌两结节的大小和高度约等。齿冠唇面三角形隆起的尖端并不偏向前方而在正中位置。齿根仅在尖端分为唇舌两枝。7.下第一及第二两臼齿大小相似。齿冠硕大,但其高度若与其长度和宽度相比,则相对极为低矮。齿冠唇面有明显的扣带,两臼齿全属五结节齿型,以前内结节为最高和最大。齿根极为粗壮,分为前后两枝,前枝较短而直,后枝则较长而明显向后倾斜。前枝末端分叉,后枝末端则为单独一尖端。8.肱骨干完全具有现代人的形式,唯一真正与现代人的不同之点在共髓腔较小和骨壁较厚,此外其三角肌粗隆特别发达。9.胫骨细长,前缘较为圆钝,中段的横切面呈圆钝的三稜形。胫骨干中央大部为海棉骨质所填充,髓腔极小。中国猿人的胫骨较苏鲁人稍细,但两者颇为相似。10.过去及本文对于中国猿人化石研究的结果,明显指出中国猿人的上肢骨与现代人极为相似;下肢骨虽已具有现代人的形式,但又有若干明显的原始性质;而牙齿及过去发现的头骨,则远较现代人为原始,脑量也远在现代人之下,说明了最初是由于劳动,由于手的使用而使手足发生了分化,脑子随着发展了起来,头骨和牙齿的形态发生了改变,这种结果进一步充实了恩格斯从猿到人的理论,阐明了“劳动创造人类”的真谛。     

澳大利亚以外第一次发现单孔目化石

迄今为止,产卵的单孔目动物仅见于澳大利亚大陆,它们从白垩纪早期一直生存到现在。阿根廷和澳大利亚科学家进行合作,在阿根廷南部巴塔哥尼亚古新世早期沉积内发现了一种鸭嘴兽牙齿。这是澳大利亚大陆以外第一次发现单孔目动物。此发现支持以下假设,即南美洲南部巴塔哥尼亚地区的生物史与该大陆其余部分不同。这次发现的化石是右上第二臼齿,齿冠形态为单孔目样,与鸭嘴兽属 Obdurodn 第二上臼齿相似,釉     

宁夏同心发现的一颗上猿牙齿

本文记述了采自宁夏同心地区中中新世(相当于通古尔早期)地层中一颗上猿的左下第二臼齿。它的齿冠形态和Hurzeler(1954)以Goriach地点为基础所总结出的上猿下臼齿的“模式”形态基本一致,而和其它几个在形态上比较接近的属,如湖猿、树猿、宽齿猿和池猿等有较明显的区别。这是我国第一颗比较可靠的上猿牙齿化石。     

陕西蓝田发现的猿人头骨化石

1.蓝田公王岭发现的猿人头骨化石材料,计有完整的额骨,顶骨的大部分,右侧颞骨的大部分,左鼻骨的大部分和右鼻骨的鼻根部,右上颌骨的体部和额突部,以及右上第二、三臼齿和左上第二臼齿。2.头盖骨的骨缝已经愈合,上第二臼齿的磨耗已达二度,估计蓝田猿人的年龄大约是三十多岁。3.由牙齿、上颌骨、颞骨锥体和颅中窝等较为细小来判断,蓝田猿人可能是女性。4.额骨前部的眶上圆枕硕大粗壮,在眼眶上方几形成一直条横行的骨嵴。圆枕的两侧端明显向外侧延展,圆枕之后明显缩窄。眼眶约呈方形,眶顶很平,没有眶上孔和泪腺窝。额骨的鳞部明显后斜,颞线隆起成为明显的骨嵴。眶上圆枕与额鳞之间没有明显的宽沟相隔。没有额窦。额骨内面的正中有宽阔而较高的额嵴。测量数值表明眉间部粗壮,额骨脑部的弧度极小,额骨极为宽阔。5.顶骨约成长方形,在正中矢状面上,顶骨短于额骨。6.颞骨锥体长轴的方向大约介于现代猿与现代人之间,与北京猿人相似。锥体较为细致,其形状和大小与现代人的女性较为接近。锥体的前后面倾斜度较大,上绿较锐,与现代人相近。7.蓝田猿人头骨的明显特点之一是其骨壁极厚,接近甚至超过北京猿人和爪哇猿人头骨相当部分厚度的上限。8.两鼻骨在根部相交约成130°角。鼻额缝与额上颌缝互相连续,约在水平位。鼻骨宽度远大于现代人,鼻骨长度明显比现代人为短。9.上颌骨及其附连的臼齿较为细致。上颌骨呈明显的齿槽凸颌。上颌骨前面与鼻腔底约成直角,两者之间有明确的分界。有小而明显的鼻前棘。右上颌骨外侧面的内侧缘有相当明显隆起的犬齿齿槽轭,在该轭与上颌骨颧突之间有从上向下延伸的沟状低凹。上第二臼齿齿冠呈长方形,前尖较为向前外方突出,有较明显的近侧颊角。上第三臼齿的形态大体与第二臼齿相似,但其齿冠长度较小,其相对宽度更大,齿冠咬合面近乎三角形。10.参考北京猿人和爪哇粗健猿人的复原头骨,进行了蓝田猿人头骨的复原。11.根据复原头骨颅内的长、宽和高计算了蓝田猿人的脑量。又根据复原的顶骨,依照比例,计算了脑量。两种方法所得的结果极为接近,估计其脑量大约为780c.c.。12.从眶上圆枕的形态和圆枕后的明显缩窄,额鳞的非常低平,头骨壁极厚,头骨高度很小,脑量很小等一系列特征,明显表示蓝田猿人的形态比北京猿人和爪哇猿人为原始,而大致与最早的爪哇粗健猿人相近,两者的地层层位也大致相当。13.为了符合人类学上的新的分类系统,建议蓝田猿人的学名为 Homo[Sinanthropus]erectus lantianensis,即把蓝田猿人和所有其他的猿人都归入直立人种;又为了便于与过去的文献资料相对照,建议把原先的属名放在新的属名之后的方括弧内,在过一定时期之后,再取消方括弧内的旧属名。     

横断山区高山姬鼠臼齿特征的研究

高山姬鼠Apodemus chevrieri分布在横断山及其附近地区。臼齿在动物的生存和生态适应中起着重要的作用。为探讨横断山环境对高山姬鼠臼齿表型变异的影响,本研究采用几何形态测量法对横断山由北到南(东北:巴塘;中部:中甸和宁蒗;南部:景东)分布的高山姬鼠的上臼齿(第一上臼齿、第二上臼齿、第三上臼齿)和下臼齿(第一下臼齿、第二下臼齿、第三下臼齿)进行测量,并进行主成分分析、薄片样条分析和多维尺度分析。研究结果表明,横断山高山姬鼠各地理种群间的臼齿有一定形态变异,薄片样条法分析显示各臼齿齿叶间有一定的形变发生,这可能与高山姬鼠在横断山各地区生存环境有关。     

豫鼠化石在我国阿尔金地区的发现（英文）

记述了在新疆巴音郭楞蒙古自治州若羌县阿尔金山地区彩虹沟首次发现的豫鼠一新种:阿尔金豫鼠(Yuomys altunensis sp.nov.)。其主要特征是臼齿的尺寸较大,比例上较宽,齿冠较高,臼齿的后小尖与后尖明显分开,后脊相对较长,但不完全,次尖明显小于原尖,舌侧内凹伸达臼齿齿冠基部,后齿带与后尖舌侧连;M3后尖为新月形,后齿带较短等。根据豫鼠臼齿的进化趋势和新种臼齿的尺寸较大、齿冠较高和舌侧内凹伸达齿冠基部的特征与Y.cavioides,Y.eleganes和Y.huangzhuangensis相近,但颊齿比例较宽判断,Y.altunensis可能与该3种处于同样的进化阶段或稍进步。其产出的地层时代很可能与它们相近或稍晚,即为晚中始新世或稍晚。     

豫鼠化石在我国阿尔金地区的发现

记述了在新疆巴音郭楞蒙古族自治州若羌县阿尔金山地区彩虹沟首次发现的豫鼠一新种:阿尔金豫鼠(Yuomys altunensis sp.nov.).其主要特征是臼齿的尺寸较大,比例上较宽,齿冠较高,臼齿的后小尖与后尖明显分开,后脊相对较长,但不完全,次尖明显小于原尖,舌侧内凹伸达臼齿齿冠基部,后齿带与后尖舌侧连;M3后尖为新月形,后齿带较短等.根据豫鼠臼齿的进化趋势和新种臼齿的尺寸较大、齿冠较高和舌侧内凹伸达齿冠基部的特征与Y.cavioides,Y.eleganes和Y.huangzhuangensis相近,但颊齿比例较宽判断,Y.altunensis可能与该3种处于同样的进化阶段或稍进步.其产出的地层时代很可能与它们相近或稍晚,即为晚中始新世或稍晚.     

中国人牙齿形态测量分析——华北近代人群臼齿齿冠及齿尖面积

本文采用数字摄影和图像分析技术对华北新石器时代人类上、下颌臼齿齿冠及齿尖基底面积进行了精确测量。在此基础上, 计算了相对齿尖基底面积。结果显示: 近代华北人上颌各臼齿齿尖大小均呈原尖>前尖>后尖>次尖的顺序, 下颌三个臼齿齿尖大小面积顺序有所不同; 上颌的后尖和次尖呈现异速生长的趋势。各臼齿齿尖相对面积的总体变异呈下颌臼齿大于上颌臼齿、M1到M3依次增加、靠近远中侧的齿尖大于近中侧的齿尖的趋势。本文首次对现代中国人臼齿相对齿尖面积进行了调查统计, 为古人类学及体质人类学研究积累了基础性数据。本研究显示利用数字摄影和图像分析技术对包括臼齿齿冠和齿尖面积在内的非线性特征进行精确的定量分析较传统的测量方法具有明显的优越性, 在古人类学和体质人类学研究中有广泛的应用前景。     

鄂西“南方古猿”和印尼早更新世若干人类化石

在鄂西发现的四枚臼齿化石曾被认为是南方古猿的。鄂西臼齿,从其齿冠尺寸和形状等来看,与非洲的有关材料对比,更接近人属成员的;与印尼早更新世有关的化石对比,与魁人等的很相似。直立人牙齿的演化趋势和变异性表明:鄂西臼齿以及印尼早更新世人类下颌骨化石更大的可能是代表一类时代较早的直立人。     

Bayes判别在巨猿分类中的应用

<正> Bayes判别分析是多元分析中的方法之一。多元分析是用数理统计的理论研究多项指标问题的一种方法,它的理论在本世纪30年代就得到相当完整的发展。最早用于考古学和古生物学的研究之中,后来应用面越来越广,目前已广泛地应用于地质、医学、心理学、行为科学、标准化、经济、海洋、农业等方面,并取得了很好的效果。通过电子计算机的运算,采用数学方法进行分类,已成为当代生物分类的三个主要流派(综合学派、分支学派和表现型学派)之一,数量分类即是表现型学派据以分类的实质内容。就世界范围而言,数量分类方法已经进入了生物各大门类的分类之中,甚至于渗透到生物学的其他领域。多元分析是数量分类中目前比较理想的方法。     

Carabelli's trait and tooth size of human maxillary first molars

Carabelli's trait is a morphological feature that can occur on the protocone of human maxillary molars. This study tests the hypothesis that Carabelli's trait is correlated statistically with the dimensions of the crown's four principal cusps or whether, as a cingular feature, the trait truly accretes onto an otherwise unaffected crown. Computer-assisted image analysis was used to measure the 6 intercusp distances and 12 angular relationships among cusp tips on the permanent first molar of 300 young adult American whites. Carabelli's complex was scored using an 8-grade ordinal scheme. Crown size was quantified in three ways, namely as 1) maximum mesiodistal and buccolingual diameters, 2) the 6 intercusp distances, and 3) the 12 angular cusp arrangements. There was no sex difference in the morphological expression of Carabelli's trait in this sample. Overall crown size and intercusp distances were significantly and progressively larger in molars with larger Carabelli's trait expressions. There are graded size responses between crown size (mesiodistal and buccolingual diameters), sizes of the four principal cusps, and morphological stage of Carabelli's complex, though the statistical relationships are appreciably stronger in males than females. Carabelli's trait occurs preferentially in larger molars. In contrast, angular (shape) relationships among cusp tips are not discernibly affected by trait size in either sex. There is the situation, then, that Carabelli's trait is developmentally correlated with crown size, but with no apparent alteration of cusp arrangements, suggesting that the increases are isometric across the occlusal table. Why the association is much weaker in females remains speculative, but these data provide yet another line of evidence that, within a population, tooth size is associated in a positive fashion with crown complexity.     

记江苏泗洪首次发现森林古猿类化石

本文记述了在江苏泗洪松林庄发现的一种古猿类化石,它以个体小、颊齿宽、有发达的齿带等特征有别于我国云南的腊玛古猿、西瓦古猿;它也有别于在同一地点、同一层位发现的双沟醉猿。其形态与非洲的Proconsul属接近,根据这些形态特点和它的地史分布,我们订立了一新属一新种:Platodontopithecus jianghuaiensis,地质时代为中新世。     

Sexual dimorphism of cusp dimensions in human maxillary molars

Cusp dimensions of human maxillary molars were compared between males and females to determine whether the later-developed, distal cusps displayed greater sexual dimorphism than the earlier-developed, mesial cusps, and whether the later-forming second molar displayed greater sexual dimorphism than the first molar. First and second permanent molar crowns (M1 and M2) were measured indirectly, using dental casts obtained from 117 Japanese (65 males and 52 females). Measurements included maximum mesiodistal and buccolingual crown diameters and the diameters of the four main cusps: the paracone, protocone, metacone, and hypocone. Mean values of crown dimensions were larger in males than in females for both M1 and M2, but the sexual difference in protocone diameter of M1 was not significant. The protocone in M1 showed the least amount of sexual dimorphism, followed by the metacone, hypocone, and paracone, while in M2, the percentage sexual dimorphism corresponded to the order of cusp formation: paracone, protocone, metacone, and hypocone. With the exception of the paracone diameter, M2 showed greater sexual dimorphism than M1. Sexual dimorphism was not always greater in the later-developed, distal cusps of M1 or M2, but the protocone, the most important cusp in terms of occlusal function, displayed the least dimorphism in M1.     

Enamel thickness of deciduous and permanent molars in modern Homo sapiens

This study presents data on the enamel thickness of deciduous (dm2) and permanent (M1-M3) molars for a geographically diverse sample of modern humans. Measurements were recorded from sections through the mesial cusps of unworn teeth. Enamel is significantly thinner on deciduous than on permanent molars, and there is a distinct trend for enamel to increase in relative thickness from M1 to M3. The relatively thicker enamel of M2s and especially M3s can be related to the overall reduction in size of more distal molar crowns, which has been attained through a differential loss of the dentine component. Enamel tends to be thicker on the protocone than on the paracone, and thicker on the protoconid than on the metaconid, but its distribution is not wholly concordant with models that predict increased thickness as a means by which to counter heavier attritional loss on these "functional" cusps. Indeed, the thickness of enamel tends to be more variable on cusp tips and occlusal surfaces than over the lateral aspects of cusps. The proportionately thicker enamel over the lateral aspects of the protocone and protoconid more likely serves as a means to prolong functional crown life by preventing cusp fracture, rather than being an adaptation to increase the attritional longevity of wear facets. The present data suggest that the human dentition is not predisposed to develop a helicoidal wear plane through the disposition of molar enamel thickness.     

南京汤山驼子洞的马科化石及其意义

200 0年在南京汤山葫芦洞直立人地点附近的驼子洞堆积中发现了又一处哺乳动物化石点。其中的马科化石有两种 :黄河马Equushuanghoensis和中国 (长鼻 )三趾马Hipparion(Proboscidipparion)sinense。这是自 1 95 9年发现黄河马化石以来首次发现黄河马的颅骨和完整的颊齿列标本。这两种马的同时出现说明含驼子洞动物群的堆积形成于早更新世。因此驼子洞堆积的发现是江宁地区下更新统的首次记录。驼子洞的黄河马和长鼻三趾马均为这两类马在秦岭淮河以南的首次记录 ,并反映了在早更新世曾发生过北方动物群跨越长江的南迁事件。     

Comparison of dental measurement systems for taxonomic assignment of first molars

Morphometrics of the molar crown is based traditionally on diameter measurements but is nowadays more often based on 2D image analysis of crown outlines. An alternative approach involves measurements at the level of the cervical line. We compare the information content of the two options in a three-dimensional (3D) digital sample of lower and upper first molars (M(1) and M(1) ) of modern human and Neanderthal teeth. The cervical outline for each tooth was created by digitizing the cervical line and then sectioning the tooth with a best fit plane. The crown outline was projected onto this same plane. The curves were analyzed by direct extraction of diameters, diagonals, and area and also by principal component analysis either of the residuals obtained by regressing out these measurements from the radii (shape information) or directly by the radii (size and shape information). For M(1) , the crown and cervical outline radii allow us to discriminate between Neanderthals and modern humans with 90% and 95% accuracy, respectively. Fairly good discrimination between the groups (80-82.5%) was also obtained using cervical measurements. With respect to M(1) , general overlap of the two groups was obtained by both crown and cervical measurements; however, the two taxa were differentiable by crown outline residuals (90-97%). Accordingly, while crown diameters or crown radii should be used for taxonomic analysis of unworn or slightly worn M(1) s, the crown outline, after regressing out size information, could be promising for taxonomic assignment of lower M1s.     

Associations between Carabelli trait and cusp areas in human permanent maxillary first molars

Few dental anthropological studies have investigated the associations between tooth crown size and crown traits in humans using quantitative methods. We tested several hypotheses about overall crown size, individual cusp areas, and expression of Carabelli cusps in human permanent first molars by obtaining data from standardized occlusal photographs of 308 Australians of European descent (171 males and 137 females). Specifically, we aimed to calculate the areas of the four main molar cusps, and also Carabelli cusp, and to compare the relative variability of cusp areas in relation to timing of development. We also aimed to compare cusp areas between males and females and to describe how Carabelli cusp interacted with other molar cusps. Measurements included maximum crown diameters (mesiodistal and buccolingual crown diameters), the areas of the four main cusps, and the area of Carabelli cusp. The pattern of relative variability in absolute areas of molar cusps corresponded with their order of formation, the first-forming paracone displaying the least variation, and the last-forming Carabelli cusp showing the greatest. Overall crown size and areas of individual cusps all showed sexual dimorphism, with values in males exceeding those in females. Sexual dimorphism was smallest for paracone area and greatest for Carabelli cusp area. Overall crown size and cusp areas were larger in individuals displaying a Carabelli cusp, especially the hypocone area. Although the combined area of the protocone and a Carabelli cusp was greater in cuspal forms than noncuspal forms, protocone area alone was significantly smaller in the former. Our findings lead us to propose that, in individuals with the genotype for Carabelli trait expression, larger molar crowns are more likely to display Carabelli cusps, whereas molars with smaller crowns are more likely to display reduced forms of expression of the trait. We suggest that the pattern of folding of the internal enamel epithelium in developing molar crowns, particularly in the protocone region, can be modified by a developing Carabelli cusp.     

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。