486 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



Figure 4. — Basic cusp and fissure patterns in mandibular first deciduous molars of 

 Paranthropus, Australopithecus, and modern Bush (from left to right). Upper row 

 illustrates actual specimens drawn under a camera lucida to the same scale; lower rov/ 

 illustrates diagrammatically the basic cusp and fissure patterns of the teeth in the upper 

 row. The anterior half of the crown in Australopithecus and modern man is highly 

 asymmetric but quite symmetric in Paranthropus. 



thropus from South Africa. In almost every feature the morphology 

 is identical with that of the latter form, up to and including the greatly 

 reduced anterior teeth coupled with veiy large cheek teeth. 



Paranthropus therefore appears to have been spread across the 

 width of the Old World with little modification. If the new potas- 

 sium-argon dates for parts of Olduvai (Leakey, Evernden, and Curtis, 

 1961) turn out to be valid, it will mean that the timespan represented 

 by the various Paranthropus specimens is rather more than a million 

 years in length. In other words, this genus would be one with a wide 

 geographical range and a long history. 



Australopithecus is not as yet known from quite so far afield. It is 

 known from East Africa near Lake Eyassi (Remane, 1951 ; Eobinson, 

 1953 and 1955), and the juvenile jaw from Bed I, Olduvai, a little 

 below the "Zinjanthropus" level (Leakey, 1961a and 1961b) certainly 

 does not belong to the latter type but bears a close resemblance to 

 Australopithecus. Some apparently large parietal bones were asso- 

 ciated with the jaw, which may mean either that Australopithecus 

 and another larger-brained hominid were contemporaneously present, 

 or perhaps that the form to wliich the jaw belonged had a larger brain 

 than had Australopithecus and therefore represents a more progressive 

 member of the same stock. The evidence is not yet clear, and more 

 finds are needed to clarify the situation. 



