138 MAMMALIAN DENTITION 



mylohyoid ridge is less clearly marked than in either modern 

 or Neandertal Man, also a primitive feature. 



The teeth, though retaining many ancestral features, are 

 typically human in form and no larger than those to be found 

 in many modern Australian skulls. 



The incisors are vertical and must have met the correspond- 

 ing upper teeth in an edge to edge bite. The canines, like 

 those of Propliopithecus, are stout but can have projected lit- 

 tle or not at all beyond the incisors. The second premolar is 

 larger than the first and more definitely bicuspid as it is in 

 Propliopithecus and the first shows none of the specialization 

 exhibited in the corresponding tooth of the recent Anthropoids. 

 Both premolars are relatively large and their labial surface 

 projects beyond the lateral border of the molar arch. Incisors, 

 canines and premolars in Heidelberg Man may be said to be 

 arranged in an oval curve, whereas those of modern Man are 

 set rather in parabolic form. 



The molars are stout but present the primitive relationship 

 of subequal size in the first and second; the third is some- 

 what reduced. All the molars exhibit a hypoconulid and are 

 relatively less transversely Avidened than many modern molars. 



Distinctively human features are obvious throughout the 

 dentition, some of which being primitive have already been de- 

 scribed. The vertical incisors%vith edge to edge bite, the stump- 

 like canines, the proportions of the premolars are all definitely 

 features of the human dentition. But it is in the pattern and 

 arrangement of the molars that the human character is most 

 strikingly seen. 



The maximum diameters of the crown in the molars are con- 

 siderably greater than those of the occlusal surface. The pro- 

 tocoled and more especially the metaconid are much reduced 

 in size whereas the hypoconid is relatively large and the ento- 

 conid greatly exaggerated. All these cusps are slightly cur- 

 tailed, hoAvever, by the rounding off of the corners of the 

 croAvn, a feature Avhich tends to reduce the area of contact be- 

 tAA^een successive teeth. The transverse and antero-posterior 



