禄丰古猿的两性差别

本文首先讨论了粗壮池猿化石标本的性别判断问题,然后把粗壮池猿和禄丰西瓦古猿分别与有关的现生猿类的两性差别进行比较研究,得出这两个进化系统性别差异的时代变化的结论。这样的结论支持禄丰西瓦古猿的系统地位的论证。

SEXUAL DIMORPHISM OF FOSSIL APES IN LUFENG

Swapithecus lufengensis shows a great magnitude of sexual dimorphism, as justified pre-viously on the basis of abundant materials. The sexual dimorphism of Laccopithecus robustus in Lufeng is also markedly expressed. Reexamination of the specimens reveals the facts that: 1) diastemata between maxillary second incisors and canines are evidently present on both sides in one specimen (PA 876), while absent in another (PA 860); 2) lower canines show a striking difference in size which could not be considered to represent different individuals of the same sex. Because of the small sample size we do not adhere to the average magnitude of the sexual dimorphism we have determined. Nevertheless, this marked expression of sex difference is de-finitely not merely an accident of small sample size. The reduction of sexual dimorphism is revealed in an additional primate lineage-gibbon lineage.Comparative studies indicate that Swapithecus lufengensis is sexually more dimorphic in dental measurements than those of chimpanzees, gorillas and orangutans. The average and the coefficient of variation of the reductions of the dimorphism indices from Sivapithecus lufen-gensis to each kind of extant great apes are used to describe the extent and the nature of dimor-phism change. Chimpanzees have the largest average and the smallest coefficient of variation in extant great apes. That seems to say, in chimpanzees, the reduction of sexual dimorphism from the condition of Sivapithecus lufengensis is most marked and, more importantly, most proportional in dental measurements. This fact strengthens the claim on the close phylogene-tic relationship between Sivapithecus lufengensis and extant chimpanzees.