Research Article Page 5 of 7
A hominin first rib discovered at the Sterkfontein Caves
44 40 36 32 28 24 20 16
StW670
AL288_1
MH2
MH1
KNM-WT15000R
KNM-WT15000L
San. H. sapiens
An. H. sapiens
Af. H. sapiens
Eu. H. sapiens
Hylobates
Pongo
Gorilla
Pan
12
Eu, European; Af, African; An, Andaman
Figure 5: Centroid size distribution of StW 670 compared to first ribs in the comparative sample. StW 670 centroid size is smaller than that of Homo erectus (KNM-WT 15000, both antimeres), the great apes (Pan, Pongo and Gorilla) and H. sapiens (including small-bodied ones); bigger than that of Hylobates; and is located between the centroid sizes of the two Australopithecus species (A. afarensis AL 288-1 and A. sediba MH1). Comparative extant sample sizes are listed in Supplementary table 1. 95% confidence interval of Af. H. sapiens
95% confidence interval of Eu. H. sapiens Af. H. sapiens Eu. H. sapiens Small H. sapiens Gorilla Hylobates Pan Pongo Fossil
Principal component 2 (16.7%)
Morphological variation along PC2
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0.00
-0.10
Cranial view of the first rib StW 670, from the Sterkfontein site. The anatomical region studied here is located inside the squared area.
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Morphological variation along PC2
-0.10
0.00
0.10
0.20
0.30
Principal component 1 (44.3%) Morphological variation along PC1
Figure 6: Principal component (PC)-shape analysis of first ribs of all specimens. Scatterplot of PC1 (44.3% of total variance) and PC2 (16.7% of total variance), and warped 3D models of proximal parts of first ribs in axial view. Note that fossil specimens (stars) are within the 95% confidence ellipse of European (Eu) and African (Af) Homo sapiens. South African Journal of Science
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Volume 112 | Number 5/6 May/June 2016