TY - JOUR
T1 - Earliest Known Hominin Calcar Femorale in Orrorin tugenensis Provides Further Internal Anatomical Evidence for Origin of Human Bipedal Locomotion
AU - Kuperavage, Adam
AU - Pokrajac, David
AU - Chavanaves, Sakdapong
AU - Eckhardt, Robert B.
N1 - Funding Information:
The authors thank Dr. Brigitte Senut of the Département Histoire de la Terre, Muséum National d'Histoire Naturelle, and Dr. Martin Pickford of the Collège de France for generously allowing access to the Orrorin tugenensis material discovered by them. They also thank Jacques Treil of the Clinique Pasteur for producing the original CT scans of the Orrorin tugenensis fossils. Dr. Richard W. Thorington, Curator Emeritus of the Department of Mammalogy, Smithsonian Institution and Bruno Frohlich were most helpful in helping to secure CT scans of the Pan troglodytes and Homo sapiens femora used for comparative purposes.
Publisher Copyright:
© 2018 Wiley Periodicals, Inc.
PY - 2018/11
Y1 - 2018/11
N2 - The calcar femorale (CF), a plate of dense bone internal to the lesser trochanter, is visible on computed tomographic images of the 6 million-year-old femoral fragment BAR 1003′00 (from the taxon Orrorin tugenensis), among the oldest specimens relevant to reconstructing the evolution of human bipedal locomotion. A strongly expressed CF has been used previously as an indicator of bipedality. If true, then there should be a quantifiable difference in the CF among hominoids. Absolute and normalized CF lengths were measured from computed tomographic images at five anatomical locations along the proximal portion of BAR 1003′00 in addition to samples of nine H. sapiens and ten P. troglodytes femora. The span of the CF superiorly to inferiorly within the proximal femur was measured by counting the number of cross-sections on which the CF occurred. A Bayesian approach was used to classify the BAR 1003′00 sample based on normalized lengths. The P. troglodytes femora were more variable both in the occurrence of the trait and, where present, its span in the proximal femur. The H. sapiens sample exhibited CF lengths that were consistently larger at each location than the P. troglodytes in absolute terms, but the normalized lengths overlap substantially. The Bayesian posterior probability test classifies the CF of BAR 1003′00 with H. sapiens. The BAR 1003′00’s calcar femorale has a strong anatomical similarity to the H. sapiens sample, supporting the conclusion that O. tugenensis is an early bipedal hominin. Anat Rec, 301:1834–1839, 2018.
AB - The calcar femorale (CF), a plate of dense bone internal to the lesser trochanter, is visible on computed tomographic images of the 6 million-year-old femoral fragment BAR 1003′00 (from the taxon Orrorin tugenensis), among the oldest specimens relevant to reconstructing the evolution of human bipedal locomotion. A strongly expressed CF has been used previously as an indicator of bipedality. If true, then there should be a quantifiable difference in the CF among hominoids. Absolute and normalized CF lengths were measured from computed tomographic images at five anatomical locations along the proximal portion of BAR 1003′00 in addition to samples of nine H. sapiens and ten P. troglodytes femora. The span of the CF superiorly to inferiorly within the proximal femur was measured by counting the number of cross-sections on which the CF occurred. A Bayesian approach was used to classify the BAR 1003′00 sample based on normalized lengths. The P. troglodytes femora were more variable both in the occurrence of the trait and, where present, its span in the proximal femur. The H. sapiens sample exhibited CF lengths that were consistently larger at each location than the P. troglodytes in absolute terms, but the normalized lengths overlap substantially. The Bayesian posterior probability test classifies the CF of BAR 1003′00 with H. sapiens. The BAR 1003′00’s calcar femorale has a strong anatomical similarity to the H. sapiens sample, supporting the conclusion that O. tugenensis is an early bipedal hominin. Anat Rec, 301:1834–1839, 2018.
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U2 - 10.1002/ar.23939
DO - 10.1002/ar.23939
M3 - Article
C2 - 30338643
AN - SCOPUS:85055265500
VL - 301
SP - 1834
EP - 1839
JO - Anatomical Record
JF - Anatomical Record
SN - 1932-8486
IS - 11
ER -