周口店新发现的中国猿人化石

This paper is a description based on the Sinanthropus materials including5 teeth and two fragments of humerus and tibia recovered since the restorationof the Choukoutien excavation in 1949.The teeth of Sinanthropus are much bigger than those of modern man.Theleft medial upper incisor bears well-developed basal tubercle on the lingualsurface.The upper first and second premolars are robust in size and theirchewing surfaces are covered with wrinkles of special patterns.The crowns ofthe first and second lower molars are characterized by their lowness in relationto their lengths and breadths.Pronounced cingulum is present on the buccalsurface of the crown.The humeral shaft is almost identical with that of modern man.Thetibial shaft is slender and its anterior border is blunt.The walls of the tibiaare extraordinarily thick and its medullary cavity is very narrow.The results of the study of Sinanthropus pekinensis by the present authorsand others clearly show that the upper extremity bones of Sinanthropus arealmost identical with those of modern man;the lower extremity bones are definitely human in form and appearance,but possess also some primitive cha-racters.The teeth and skulls possess many primitive features.The cranialcapacity is considerably smaller than that of recent man.It is due to labour,and the operations of the hands that the upper extremity is differentated fromthe lower one.The differentiation of the extremities is followed by the deve-lopment of the brain and the brain case.These results further enrich Engels'theory of the transition from ape to man and testify to the truth that“labour(?)eated man himself”.