NO. 12 JAW OF PILTDOWN MAN MILLER 15 



physis to base of condyle, is like that of a chimpanzee. Hence in 

 order to fit its articulating surface to that of the skull it would be 

 necessary to imagine an abrupt change of plan in the few millimeters 

 of condyle that have been lost. 



Another incongruity is found when the area of origin of the tem- 

 poral muscle on the skull is compared with that of its insertion on the 

 mandible. Both regions have been carefully described and figured 

 (Dawson and Woodward, 1913, pp. 128, 131, pi. 18, fig. 3, pi. 20, figs. 

 2a, 2c) . The anterior border of the muscle appears to have extended 

 upward on the frontal with somewhat unusual abruptness, an impres- 

 sion that may be heightened by the way in which the bone is broken. 

 The posterior border was not carried very far back on the parietal. 

 In general features the area of origin for the whole muscle is strictly 

 human, and its extent is considerably less than in many of the human 

 skulls with which I have compared it. In all three genera of Pongidce 

 this area is much greater in proportion to the size of the animal, push- 

 ing its way in adult individuals gradually over the braincase to median 

 line, where the muscles of the two sides are often separated merely by 

 a sagittal crest. 1 The area of insertion of the muscle on the Piltdown 

 mandible has not only all the more important general characters 

 peculiar to this region in Pan; it has also the individual features 

 which in living members of that genus are connected with the greatest 

 extension of the area of origin of the muscle on the skull. Young 

 chimpanzees show a slight approximation to Homo in the form of the 

 area on which the temporal muscle is inserted. The ridge which 

 extends upward from the base of the coronoid process is broad and 

 low, giving this whole region the smoothly convex appearance usually 

 found in members of the family Hominidce. With increasing age the 

 ridge becomes narrower and the region behind it changes from flat 

 to concave; finally the surface of the main ridge becomes marked by 

 secondary ridgelets which give extreme strength of attachment to the 

 muscle-fibers. This last stage of roughening on the mandible is asso- 

 ciated in chimpanzees with the closest approach of the upper end of 

 the muscle to the median line of the braincase and especially with the 

 formation of a sagittal crest. It is well-marked in the Piltdown jaw. 

 In order to associate this jaw with the braincase it would therefore be 

 necessary to assume the existence of an animal related to both Homo 

 and Pan but with a temporal muscle working on a different mechan- 

 ical scheme from either ; that is, moderate in size and strength at the 



Most frequently developed in Gorilla, least frequently in Pan. 



