A 3-DIMENSIONALLY BASED MORPHOLOGICAL ANALYSIS OF THE EARLY HOMINID

本项目的目的是通过使用激光和/或ct扫描获得的数字化全表面数据集，对原始人牙齿进行基于三维的形态学分析。在本研究中，我们开发了一个程序和方法，有效地获得数百个连续的ct切片与工业micro-ct扫描仪，然后提取精确的表面绘制数据集的3-d体ct数据。我们进一步开发了一个集成的软件系统，可以处理基于激光和ct的数据集，并使用测试对象进行体积，表面积，投影面积，弯曲长度的全面准确性测试。然后，我们继续使用类似的数字化参数进行树冠特征的形态测量分析。ct系统的使用允许更通用的比较数据采集，我们收集了32个人类、40个黑猩猩、27个倭黑猩猩、42个猩猩和10个大猩猩臼齿的ct数据集。高质量的铸件被用于获得激光扫描的3D数据集的53个早期人类磨牙。这些数据集目前正在分析中，但我们能够从功能上描述早期原始人类第一磨牙的状况。而食果物种的臼齿，如潘和庞戈是低冠与广泛的咬合凹，南方古猿和早期的家臼齿的结构设计，以最大限度地增加咬合表面积在磨损的条件下，往往有一个高的基底部分的冠。这些特征对于健壮和非健壮物种都是共同的，尽管两者在尖瓣面积比例和其他形态上存在相当大的差异。

The aim of the present project was to conduct 3-dimensionally based morphological analysis of the hominind bentition by means of using digitized whole surface datasets obtained by laser and/or ct scanning. In the present study, we developed a procedure and method of efficiently obtaining several hundreds of serial ct slices with an industrial micro-ct scanner, then extracting accurate surface rendered datasets from the 3-d volume ct data. We further developed an integrated software system that handles both laser and ct-based datasets, and conducted comprehensive accuracy tests of volume,surface area, projected area, curved lengths using test objects. We then proceeded to conduct morphometric analysis of crown features using similarly digitized parameters. The use of the ct-system allows more versatile comparative data acquisition, and we collected ct datasets of 32 human, 40 chimpanzee, 27 bonobo, 42 orangutan, and 10 gorilla molars. High quality casts were used in obtaining laser-scanned 3D datasets of 53 early hominid molars. These datasets are currently being analyzed, but we were able to characterize functionally the early hominid first molar condition. Whereas the molars of frugivorous species such as Pan and Pongo are low-crowned with broad occlusal fovea, Australopithecus and early Home molars are structurally designed to maximize occlusal surface area in a worn condition and tend to have a tall basal portion of the crown. These characteristics are common to both robust and non-robust species, despite considerable differences between the two in cusp area proportions and other morphologies.