. Bulletin of the British Museum (Natural History), Geology. . Fig. 3 KNM-RU 1840 'Kenyapithecus africanus' mandible, x 1. A, cross-section of the symphysis in the orientation of Leakey (1967: fig. 5e) with the genial fossa opening downwards and the tooth row sloping downwards. B, alternative orientation showing tooth rows level and genial fossa opening posteriorly. The 'chin' is much less obvious in the second orientation. The mandibular body varies in the same way as the symphysis. The largest specimens of P. nyanzae have body depths as deep as or deeper than P. major, but they are more grac
. Bulletin of the British Museum (Natural History), Geology. . Fig. 3 KNM-RU 1840 'Kenyapithecus africanus' mandible, x 1. A, cross-section of the symphysis in the orientation of Leakey (1967: fig. 5e) with the genial fossa opening downwards and the tooth row sloping downwards. B, alternative orientation showing tooth rows level and genial fossa opening posteriorly. The 'chin' is much less obvious in the second orientation. The mandibular body varies in the same way as the symphysis. The largest specimens of P. nyanzae have body depths as deep as or deeper than P. major, but they are more gracile. The mental foramen is single and situated beneath P3/P4. The concavity for the buccal cavity is pro- nounced and in some cases seems to extend surprisingly far towards the base of the mandible. It always extends down to the level of the mental foramen, which is just over one third of the way up from the inferior border of the mandible. The inferior border is bluntly rounded. The mandibular ramus is preserved in a broken state on specimen RU 1674. It has been de- scribed in detail by Maclnnes (1943) and Clark & Leakey (1951 : 46-47). It is high and very large relative to the size of the body of the mandible, and has a pronounced posterior slope. A remark- able feature of this specimen is the posterior divergence of the mandible which leads to the bi- condylar width of 112 mm. This is similar to values in male chimpanzees. (See Fig. 4.) Upper incisors (Tables 3-4, p. 138-140). The I1 is very high-crowned. The mesiodistal length is greater than the buccolingual length but is less than the height. The lingual surface of the tooth is moderately concave and has a broad stout median pillar running halfway to the tip of the crown, and composed of a number of ridges that originate from the prominent lingual cingulum. Wear is usually confined to the incisive edge, and in one case only (MB 104) does it extend several millimetres along the lingual surface of the tooth. There are s
Size: 1357px × 1840px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
