Fig 1.
Locations of cephalometric landmarks on Pan troglodytes skull in norma frontalis and norma lateralis.
See abbreviations in Table 1.
Table 1.
Cephalometric landmarks including their abbreviations, definitions, planes of measurement, and angles of measurement.
Table 2.
Descriptive statistics of facial soft tissue thickness in mm for Pan troglodytes.
Table 3.
Descriptive statistics of craniometric dimensions in mm for Pan troglodytes.
Fig 2.
Scatterplots showing four examples of covariation between facial soft tissue and craniometric measurements in chimpanzees.
(A) Correlation between canine eminence and mandibular symphysis height. (B) Correlation between ectomolare2 and nasal breadth. (C) Correlation between euryon and distance from vertex to gnathion. (D) Correlation between mid-ramus and bigonial breadth.
Table 4.
Chimpanzee-derived linear regression models for medial and bilateral facial soft tissue thicknesses.
Table 5.
Average differences between predicted soft tissue thicknesses and ground truth values in this study sample of chimpanzees (Pan troglodytes).
Fig 3.
3D facial approximations of PRI-Cleo (Pan troglodytes; A), 29655 (Pan paniscus; B), and composite skull of Australopithecus africanus (Sts 5 and Sts 52; C) in right three quarter view (30° rotation from full face), norma frontalis and, norma lateralis. Note that the angle of the head in each facial approximation follows standard orientation methods established for modern humans. For P. troglodytes, P. paniscus, and A. africanus this angle may be unjustified biomechanically (Johanson, 1981). Scale bar = 10 cm.
Fig 4.
Depth chart comparison of observed (○) and predicted (●) facial soft tissue thickness values between facial approximations of PRI-Cleo (Pan troglodytes; A), 29655 (Pan paniscus; B), and modern human male of European descent (Homo sapiens; C). Predicted thickness values for the composite skull of Australopithecus africanus (Sts 5 and Sts 52; D) are also shown. See abbreviations in Table 1.
Fig 5.
Line charts of Pan troglodytes (○) and Homo sapiens (●) means comparing values with differences < 2 mm (A) and differences > 2 mm (B).
Fig 6.
Skulls of PRI-Cleo (Pan troglodytes; A), 29655 (Pan paniscus; B), the composite skull of Australopithecus africanus (Sts 5 and Sts 52; C), and modern human male of European decent (Homo sapiens; D) in norma lateralis. Note the similarities and differences in the profiles of the facial projection and their implications for the thicknesses of the muscles that act on the masticatory system between these hominid species. Scale bar = 10 cm.
Table 6.
Craniometrics taken from skulls of PRI-Cleo (Pan troglodytes), 29655 (Pan paniscus), composite skull of Australopithecus africanus (Sts 5 and Sts 52) and modern human male of European descent (Homo sapiens).
Fig 7.
Final facial approximations performed on the skulls of PRI-Cleo (Pan troglodytes; A), 29655 (Pan paniscus; B), and composite skull of Australopithecus africanus (Sts 5 and Sts 52; C). The facial features for PRI-Cleo and 29655 were extrapolated from photographic evidence of chimpanzees and bonobos. The final approximation of A. africanus represents only what the regression models of the present study can provide. Scale bar = 10 cm.