步氏巨猿的牙齿釉质发育不全

在步氏巨猿后部齿的绝大部分类别中检出有釉质发育不全的标本,患釉质发育不全的个体数高达14.3—17.9％。类似的情况可见之于南非的南方古猿类。步氏巨猿的釉质发育不全很大可能是由于营养上的原因。     

消息与动态

1990年7月,中国科学院古脊椎动物与古人类研究所、美国耶鲁大学和湖北省文物考古研究所有关人员联合组成的野外调查小组在建始县工作时,鉴定了该县文物管理所收藏的化石,其中有一枚牙齿为步氏巨猿的右下第二前臼齿,与这枚齿化石同时出土的还有一些动物化石。它们是由建始县桑园乡麻扎坪村农民李明武在挖地时发现的。     

步氏巨猿犬齿与前臼齿咬合关系的观察

步氏巨猿的上犬齿与下第一前臼齿的咬合关系有两种主要类型:一是相似于“猿类”的,另一相似于“人类”的。前者为雄性个体所具有,后者为雌性个体所具有。另有少数个体的则是中间类型。上犬齿与下第一前臼齿的咬合特征的分类学上的意义是可疑的。至少就绝大部分雄性步氏巨猿个体来说,很难认为其犬齿是参与臼齿的功能。步氏巨猿下第一前臼齿之所以呈双尖类型,与其犬齿并无直接的关系。     

湖北巨猿牙齿化石龋病观察

本文共调查了267枚从鄂西山区收集的巨猿牙齿化石现发生情况,发现其中有52枚（占19.5%)的颊齿有程度不同的龋蚀现象,其患龋率显著高于古人类,同时也高于广西巨猿的患龋率。巨猿牙齿的这种高频率龋蚀现象,除牙齿结构因素外,可能与该物种食性的狭窄化和营养贫乏导致牙齿不良钙化有关,是伴随巨猿体型的巨型化而趋向该物种衰退和绝灭的病理表征之一。     

巨猿牙齿釉质厚度及对食性适应与系统演化的意义

步氏巨猿(Gigantopithecus blacki)是更新世时期生活于我国华南地区的一种超大型猿类, 它的体态特征和演化分类倍受关注。牙齿釉质厚度在探讨灵长类食性、环境适应以及系统演化方面具有重要意义。本文利用显微CT技术构建18颗巨猿臼齿虚拟模型, 测量其釉质厚度。将巨猿釉质厚度与现代人、现生类人猿、古人类、中新世古猿及其他现生灵长类进行比较, 从牙齿釉质厚度探讨巨猿的食性适应和系统演化问题。结果发现巨猿的实测釉质厚度是目前所有已知现生和化石灵长类中最厚的, 只有傍人、南非早期人属及奥兰诺古猿三种化石灵长类与之接近; 如果考虑不同物种牙齿与身体大小的关联因素, 相对釉质厚度指数显示巨猿属于"厚"釉质类型, 但非"超厚"类型, 低于奥兰诺古猿、傍人、南非早期人属; 巨猿与某些中新世古猿 (如原康修尔猿尼安萨种、非洲古猿)、南方古猿、东非早期人属、亚洲直立人以及现代人、现生卷尾猴的相对釉质厚度指数相近。巨猿的厚釉质特征与其食性和环境适应密切相关, 使得牙齿具有非常强的抗磨损功能, 能够适应长时间的咀嚼和研磨食物。从釉质厚度的系统演化角度推测, 厚釉质应该是人类祖先的特征性状, 巨猿有可能是早期人类支系演化过程中的一个特化旁支, 同时也不排除巨猿是从某种具有厚釉质的中新世古猿旁支平行演化而来的可能性。     

辽宁北票地区一新的甲龙化石

记述了辽宁省北票地区的甲龙化石一新属新种 :步氏克氏龙 (Crichtonsaurusbohlinigen .etsp.nov.)。其主要特征是 :中等大小的甲龙 ,下颌骨较低 ,外侧无骨甲覆盖 ;牙齿小 ,齿冠上有垂直向的棱嵴和边缘小齿 ,齿环发育不全 ,有愈合的颈甲板 ,膜质骨甲形态多样 ,尾后部的椎体相连结成棒状 ,两侧有排列对称的甲板。步氏克氏龙的发现对探讨北票地区晚中生代地层的划分和时代归属 ,以及对甲龙类的系统演化和地理分布均具有重要的意义。     

我国首次发现的丘齿鼷鹿

这里记述的丘齿鼷鹿(Dorcabune)的材料是我国广西柳城楞寨山硝岩洞(由于出产大量的巨猿化石又称“巨猿洞”)中采集的偶蹄类化石的一部分。丘齿鼷鹿的材料,(?)在巨猿洞大量的哺乳动物化石中数量甚少,仅发现了十个牙齿,它的发现对我国第四纪哺乳动物的研究,特别是对柳城巨猿洞动物群的性质的确定以及地层对比,有重要的意义。     

关于中国南方剑齿象-熊猫动物群和巨猿的时代

通过1957—1960年间,在华南地区的野外工作,发现了剑齿象-熊猫(Stegodon-Ailu-ropoda)动物群的许多新的化石地点。从广西大兴县牛睡山和柳城楞寨山两个地点发现了出乎意外的大量的巨猿(Gigantopithecus)牙齿(约900个包括3个保存很好的下颌骨)。这些材料已有了初步的报导。随着这些发现的发表,对于步氏巨猿(Gigan-topithecus blacki)的系统关系和时代问题发生了不同的意见。     

元谋人牙齿化石的再研究

本文研究表明,元谋人上中门齿跟猿类(包括巨猿)有显著差别,不能归于猿类之列;它们跟智人类型的上中门齿也有显著区别,不可能是后期人类的牙齿。跟目前已发现的非洲南猿类型标本相比较,形态上的差异也是相当大的,看来还不能视作同类;而跟北京人同类牙齿相比较,基本形态是相当接近的,但也不能不看到,与后者尚有一些不同之处,不过,两者的差异程度远不及它们跟南猿类型牙齿的差异大。通过本文研究,在目前现有材料的基础上,我们认为元谋人上中门齿是我国南方迄今已发现的早期类型的直立人代表,它们形态上与北京人的不同处,反映了它们的原始性,反映了可能具有从纤细南猿向直立人过渡的特点。     

山西静乐贺丰上新世的步氏羚羊（Gazella balcki Teilhard and Young,…

重新厘定后,步氏羚羊（Ｇａｚｅｌｌａｂｌａｃｋｉ）的主要特征是个体中等大小,脑颅部宽而短,枕面向后突出不明显,枕髁与枕面处的一同一平面中,基枕面平,呈方形,具宽浅而长的中纵沟;角心纤细,短而直,从角基向角顶方向迅速变尖,基部横切面为次圆形,颊齿高冠,前臼齿列短和ｐ４有封闭的前内谷等,它出现在我国山西上上新统的地层中,依据头骨和颊齿的性状,它可有是现生种Ｇ．ｐｉｃｔｉｃａｕｄａｔａ和Ｇ．ｇｕｔｈｕｒ     

Dental metric assessment of the omo fossils: implications for the phylogenetic position of Australopithecus africanus

The discovery of Australopithecus afarensis has led to new interpretations of hominid phylogeny, some of which reject A. africanus as an ancestor of Homo. Analysis of buccolingual tooth crown dimensions in australopithecines and Homo species by Johanson and White (Science 202:321-330, 1979) revealed that the South African gracile australopithecines are intermediate in size between Laetoli/hadar hominids and South African robust hominids. Homo, on the other hand, displays dimensions similar to those of A. afarensis and smaller than those of other australopithecines. These authors conclude, therefore, that A. africanus is derived in the direction of A. robustus and is not an ancestor of the Homo clade. However, there is a considerable time gap (ca. 800,000 years) between the Laetoli/Hadar specimens and the earliest Homo specimens; "gracile" hominids from Omo fit into this chronological gap and are from the same geographic area. Because the early specimens at Omo have been designated A. afarensis and the later specimens classified as Homo habilis, Omo offers a unique opportunity to test hypotheses concerning hominid evolution, especially regarding the phylogenetic status of A. africanus. Comparisons of mean cheek teeth breadths disclosed the significant (P less than or equal to 0.05) differences between the Omo sample and the Laetoli/Hadar fossils (P4, M2, and M3), the Homo fossils (P3, P4, M1, M2, and M1), and A. africanus (M3). Of the several possible interpretations of these data, it appears that the high degree of similarity between the Omo sample and the South African gracile australopithecine material warrants considering the two as geographical variants of A. africanus. The geographic, chronologic, and metric attributes of the Omo sample argue for its lineal affinity with A. afarensis and Homo. In conclusion, a consideration of hominid postcanine dental metrics provides no basis for removing A. africanus from the ancestry of the Homo lineage.     

Molar enamel thickness and dentine horn height in Gigantopithecus blacki

Absolutely thick molar enamel is consistent with large body size estimates and dietary inferences about Gigantopithecus blacki, which focus on tough or fibrous vegetation. In this study, 10 G. blacki molars demonstrating various stages of attrition were imaged using high-resolution microtomography. Three-dimensional average enamel thickness and relative enamel thickness measurements were recorded on the least worn molars within the sample (n = 2). Seven molars were also virtually sectioned through the mesial cusps and two-dimensional enamel thickness and dentine horn height measurements were recorded. Gigantopithecus has the thickest enamel of any fossil or extant primate in terms of absolute thickness. Relative (size-scaled) measures of enamel thickness, however, support a thick characterization (i.e., not "hyper-thick"); G. blacki relative enamel thickness overlaps slightly with Pongo and completely with Homo. Gigantopithecus blacki dentine horns are relatively short, similar to (but shorter than) those of Pongo, which in turn are shorter than those of humans and African apes. Gigantopithecus blacki molar enamel (and to a lesser extent, that of Pongo pygmaeus) is distributed relatively evenly across the occlusal surface compared with the more complex distribution of enamel thickness in Homo sapiens. The combination of evenly distributed occlusal enamel and relatively short dentine horns in G. blacki results in a flat and low-cusped occlusal surface suitable to grinding tough or fibrous food objects. This suite of molar morphologies is also found to varying degrees in Pongo and Sivapithecus, but not in African apes and humans, and may be diagnostic of subfamily Ponginae.     

广西布兵盆地么会洞发现的巨猿牙齿化石

对广西布兵盆地么会洞发现的哺乳动物化石的研究显示,该地点的部分高等灵长类牙齿化石中,16枚可归入巨猿步氏种(Gigantopithecus blacki),其形态特征与中国、越南和印度北部发现的巨猿化石相似。在尺寸大小上与重庆巫山和广西柳城巨猿洞的相近,暗示么会洞巨猿的时代与之接近,且共生的哺乳动物群也非常相似,指示它们之间相近的生物地层年龄。古地磁分析结果显示其时代在奥都威正极性世。     

Posterior tooth size, body size, and diet in South African gracile Australopithecines

A model relating relative size of the posterior teeth to diet is suggested for forest and savanna primates and Homo. Relative tooth size is calculated for the South African gracile australopithecine sample using posterior maxillary area sums and size estimates based on four limb bones. A number of limbs were shown to be non-hominid. Comparisons show the South African gracile sample apparently adapted to a very heavily masticated diet with relative tooth size significantly greater than any living hominoid. Periodic intensive utilization of grains and roots combined with scavenged animal protein are suggested as the most likely dietary reconstruction.     

Comparative observations on the tooth root morphology of Gigantopithecus blacki

The extinct great ape Gigantopithecus blacki from the middle Pleistocene of China and Vietnam is known only from dental and mandibular remains, and its dietary specializations remain contentious. Here, for the first time, we describe the root morphology in G. blacki using computed tomography and three-dimensional image processing. We quantify the tooth root lengths and surface areas of the female G. blacki mandible No. 1 from the Liucheng Cave and compare it to a sample of extant great apes and humans, as well as the giant panda (Ailuropoda melanoleuca) and the American black bear (Ursus americanus). The results show that, in G. blacki, the pattern of mandibular root numbers-particularly that of the premolars-corresponds with that of Gorilla gorilla, Pan troglodytes, and Pongo pygmaeus. However, G. blacki can be distinguished from the extant hominids by having relatively higher values for postcanine root length and surface area, both absolutely and relative to mandibular size (except for premolar root lengths of humans). The relatively large postcanine root surface areas, which are most similar to A. melanoleuca, suggest that the dentition of G. blacki was adapted to sustaining relatively large occlusal forces needed to fracture mechanically resistant foods such as bamboo.     

An analysis of australopithecine dentition

The means and variances of dental length, breadth, and area measurements of South and East African gracile and robust australopithecines are analyzed to determine the existence of statistically significant differences due possibly to different niche utilization and divergent evolution. The study material is divided into four groups: South African gracile, South African robust, East African gracile, and East African robust. Comparison of East and South African graciles, East African robusts and graciles, and South African robusts and graciles shows few significant F-ratios; a high frequency of significance is observed between East and South African robusts. High frequencies of significance are observed in t tests between all groups. Probit analysis, carried out on each of the four groups separately for each measurement, shows little or no significant deviation from normality; similar results are obtained when the groups are combined, suggesting the joint-normal distribution of the total australopithecine sample. High frequencies of significant t tests and low frequencies of significant F-ratios are observed when all graciles are compared with all robusts; yet few significant t tests and many significant F-ratios occur when all East African forms are combined with all South African forms. Observed differences in dental measurements in australopithecines tend to occur on a regional rather than a morphologic basis, especially with regard to robust samples from South and East Africa. While analysis of variance and probit analysis cannot be used to establish taxonomic divisions, results suggest the inappropriateness of dental measurements in establishing an australopithecine taxonomy.     

Enamel thickness and development in a third permanent molar of Gigantopithecus blacki

A ground section was prepared from a lower right M3 attributed to Gigantopithecus blacki as close as possible to axial plane of the mesial cusps. Daily cross striations were imaged, measured and counted in each cusp using polarised light microscopy. Long-period striae of Retzius were counted in the lateral enamel and their periodicity determined from counts and measurements of daily cross striations between adjacent striae. Cross striation spacings in the cusps were between 3.8 microm at the enamel dentine junction and 6 microm close to the enamel surface. Cuspal enamel formation times were long (800 days in the protoconid and 620 days in the metaconid). Linear enamel thickness was as much as 3.75 mm in the protoconid. There were 63 and 61 long-period striae of Retzius in the mesial aspects of the lateral enamel and the periodicity was 11 days. Lateral enamel formation took 1493 and 1291 days and when summed with cuspal enamel formation times totalled 4 years in the protoconid and 3.5 in the metaconid. Relative enamel thickness was 23, calculated through the mesial cusps. This falls short of that in the so-called 'thick hyper-thick' enamel described in 'robust' australopithecines to which Gigantopithecus blacki has previously been compared in both its dental and mandibular morphology. With respect to enamel thickness, therefore, Gigantopithecus blacki falls squarely among an increasingly large number of Miocene hominoids that can all be described as having 'thick enamel'.     

广西大新黑洞哺乳动物化石

<正> 本文研究的材料是1955年初,由裴文中教授领导的野外考察队在广西大新、武鸣、柳州、崇左、扶绥等县进行古人类和第四纪哺乳动物洞穴调查时发现的。这批材料发现于大新县正隆乡牛睡山黑洞(野外编号:5657),计有巨猿等多种哺乳动物化石。巨猿牙齿化石已由裴文中、吴汝康共同研究并于1956年发表了专题报告。报告中曾提到,与巨猿同时发现的其它哺乳类化石有猩猩、大熊猫、剑齿象和巨獏等,其地质时代为更新世中期。