likewise exceeds the top of the australopithecine sample range. Such large 

 parietals necessarily covered a larger brain than that of any australopithe- 

 cine known hitherto. 



That fact was clearly acknowledged by Robinson in 1962, at which 

 time he endeavored to show that early stone tools were not made by 

 Australopithecus sensu stricto (i.e., A. africanus). In his investigation he 

 specifically included "pre-Zinjanthropus" as a larger-brained contemporary 

 of A. africanus. Thus, he stated: 



In fact, there is evidence throughout the entire australopithecine period either 

 proving or suggesting the presence of a more advanced form of hominid. There 

 are the large parietals in the "pre-Zinj" level of Olduvai, "Telanthropus" at 

 Swartkrans. . . . [Robinson 1962a, p. 102] 



Reconstructing the biparietal arch. It was a logical and impera- 

 tive step, after the parietals had been measured, to attempt an estimate 

 of the cranial capacity. First the missing parts of the 2 parietal bones 

 had to be reconstructed. This was not difficult, because the entire coronal 

 and temporal borders were present on the left bone and the entire 

 lambdoid (or occipital) border on the right. In addition, the anterior 

 part of the sagittal border was present on the left parietal and the 

 posterior part of that border on the right. Further, both bones had the 

 asterionic region intact and symmetrical. 



Once the 2 bones had been thus restored, the archway formed by them 

 had to be reconstructed (Figures 15 and 16). The first reconstruction of the 

 biparietal part of the calvaria was made by Dr. L. S. B. Leakey and myself; 

 later a second reconstruction was made independently by Mr. A. R. Hughes 

 and myself. The 2 reconstructions differed from each other by a negligibly 

 small margin: thus, the biasterionic breadth of the arch differed between 

 the 2 reconstructions by scarcely 2 mm. (Tobias 1964, 1965a). There was 

 possible only a narrow range of naturally appearing anatomical relation- 

 ships between the left and right parietal bones: the eye soon detected the 

 discrepancy whenever the angle between the 2 bones (along the sagittal 

 suture) was so great or so small as to produce an appearance differing 

 appreciably from that shown by other hominoid crania. The narrowness 

 of this range of tolerability is testified to by the 2 mm. discrepancy between 

 the 2 reconstructions. In any event, the irrelevance of slight and even 

 moderate variations in this angle for the estimation of cranial capacity was 

 effectively demonstrated by Holloway (1965), as described below. 



^ 62 



