Institute of Vertebrate Palaeontology and Palaeoanthropology, Academia Sinica, Beijing, China.
Departments of Anatomy and Cell Biology, and Biological Sciences, University of Southern California, Los Angeles.
Am J Primatol. 1983;5(4):303-344. doi: 10.1002/ajp.1350050403.
The pattern of overall dental dimensions in over 900 teeth of ramapithecines from Lufeng in China is examined using frequency distribution histograms and fitted normal curves, and compared with data for extant hominoids. A prior study has demonstrated unequivocally that at least two groups of animals must have existed at Lufeng [Wu and Oxnard, 1983; Oxnard, 1983a]. The present investigation confirms this finding in more detail. In addition it shows that one fossil group possesses smaller teeth with a lesser degree of sexual dimorphism and approximately equal numbers of adult males and females, and the other possesses larger teeth with a rather larger degree of sexual dimorphism and a female-male ratio that may have approximated from as low as 2:1 to as high as 4:1. Comparisons of patterns of difference along the tooth row demonstrate that both these forms differ from modern apes in their sexual dimorphism, the smaller form being more like humans than the larger, which is more like apes, especially orangutans. Comparisons of the areas of the canine teeth with each of the other functional segments of the tooth row again show that the smaller form is basically similar to modern humans and that the larger resembles extant great apes. Comparisons of other functional dental areas seem to relate to dietary and masticatory functions. Thus the cutting areas are large relative to the chewing areas in omnivorous humans, whereas in the essentially vegetarian great apes this ratio is smaller. The smaller fossil resembles the human condition and may have been somewhat omnivorous; the larger one more resembles the apes and may have been somewhat more vegetarian. However, these comparisons also show that the way in which the larger form resembles the apes is associated with special development of the canines, which is different from that in any modern ape. Comparisons show that the canines in the larger form project far beyond the normal line of tooth crowns. Finally, comparisons show that canine sexual dimorphism in height is marked in the larger form. Neither of these last two features is true of the smaller fossil. These findings have implications for our understanding of the evolution of early pongids and hominids, and for the evolution of primate sexual dimorphisms and dental mechanisms.
对产自中国禄丰的 900 多颗巨猿牙齿的整体牙齿尺寸模式进行了研究，使用频率分布直方图和拟合正态曲线进行了分析，并与现生大猿类的数据进行了比较。先前的研究已经明确表明，禄丰至少存在两组动物[Wu 和 Oxnard，1983；Oxnard，1983a]。本研究更详细地证实了这一发现。此外，它还表明，一个化石群具有较小的牙齿，性二态性程度较低，成年雄性和雌性数量大致相等，另一个化石群具有较大的牙齿，性二态性程度较大，雌性与雄性的比例可能接近 2:1 至 4:1。沿着牙齿行比较差异模式表明，这两种形式在性二态性方面都与现代猿类不同，较小的形式比较大的形式更像人类，而较大的形式更像猿类，尤其是猩猩。比较犬齿与牙齿行其他功能段的面积再次表明，较小的形式与现代人类基本相似，而较大的形式与现生大猿类相似。比较其他功能牙齿区域似乎与饮食和咀嚼功能有关。因此，杂食性人类的切割区域相对较大，而在以植物为主食的大猿类中，这个比例较小。较小的化石更类似于人类的情况，可能是杂食性的；较大的一个更类似于猿类，可能是素食者。然而，这些比较也表明，较大形式与猿类相似的方式与犬齿的特殊发育有关，这与任何现代猿类都不同。比较表明，较大形式的犬齿远远超出了正常牙冠线。最后，比较表明，较大形式的犬齿在高度上具有明显的性二态性。这些最后两个特征在较小的化石中都不存在。这些发现对我们理解早期猩猩和人科动物的进化以及灵长类动物的性二态性和牙齿机制的进化具有重要意义。
