TY - JOUR
T1 - New postcranial fossils of Australopithecus afarensis from Hadar, Ethiopia (1990-2007)
AU - Ward, Carol V.
AU - Kimbel, William
AU - Harmon, Elizabeth H.
AU - Johanson, Donald
N1 - Funding Information:
For permitting access to fossil and comparative collections, thanks go to the directors and staff of the National Museum of Ethiopia, Cleveland Museum of Natural History, National Museums of Kenya, Ditsong National Museum of Natural History (formerly Transvaal Museum), and the University of the Witwatersrand Medical School. We also thank Chris Campisano, Deborah Cunningham, Michelle Drapeau, Dana Duren, Erella Hovers, Bruce Latimer, and Meave Leakey for help and comments. Special thanks go to Zeresenay Alemseged for assistance with data collection. The analytical research reported here was supported by the National Science Foundation ( NSF SBR-9601025 , NSF BCS-0716244 , NSF BCS-0333296 ), University of Missouri Research Board , University of Missouri Research Council , and the Institute of Human Origins at Arizona State University . CVW, WHK and DCJ dedicate this work to the memory of our friend and colleague Elizabeth Harmon, whose contributions considerably enhanced the field and analytical research resulting in this paper.
PY - 2012/7
Y1 - 2012/7
N2 - Renewed fieldwork at Hadar, Ethiopia, from 1990 to 2007, by a team based at the Institute of Human Origins, Arizona State University, resulted in the recovery of 49 new postcranial fossils attributed to Australopithecus afarensis. These fossils include elements from both the upper and lower limbs as well as the axial skeleton, and increase the sample size of previously known elements for A. afarensis. The expanded Hadar sample provides evidence of multiple new individuals that are intermediate in size between the smallest and largest individuals previously documented, and so support the hypothesis that a single dimorphic species is represented. Consideration of the functional anatomy of the new fossils supports the hypothesis that no functional or behavioral differences need to be invoked to explain the morphological variation between large and small A. afarensis individuals. Several specimens provide important new data about this species, including new vertebrae supporting the hypothesis that A. afarensis may have had a more human-like thoracic form than previously appreciated, with an invaginated thoracic vertebral column. A distal pollical phalanx confirms the presence of a human-like flexor pollicis longus muscle in A. afarensis. The new fossils include the first complete fourth metatarsal known for A. afarensis. This specimen exhibits the dorsoplantarly expanded base, axial torsion and domed head typical of humans, revealing the presence of human-like permanent longitudinal and transverse arches and extension of the metatarsophalangeal joints as in human-like heel-off during gait. The new Hadar postcranial fossils provide a more complete picture of postcranial functional anatomy, and individual and temporal variation within this sample. They provide the basis for further in-depth analyses of the behavioral and evolutionary significance of A. afarensis anatomy, and greater insight into the biology and evolution of these early hominins.
AB - Renewed fieldwork at Hadar, Ethiopia, from 1990 to 2007, by a team based at the Institute of Human Origins, Arizona State University, resulted in the recovery of 49 new postcranial fossils attributed to Australopithecus afarensis. These fossils include elements from both the upper and lower limbs as well as the axial skeleton, and increase the sample size of previously known elements for A. afarensis. The expanded Hadar sample provides evidence of multiple new individuals that are intermediate in size between the smallest and largest individuals previously documented, and so support the hypothesis that a single dimorphic species is represented. Consideration of the functional anatomy of the new fossils supports the hypothesis that no functional or behavioral differences need to be invoked to explain the morphological variation between large and small A. afarensis individuals. Several specimens provide important new data about this species, including new vertebrae supporting the hypothesis that A. afarensis may have had a more human-like thoracic form than previously appreciated, with an invaginated thoracic vertebral column. A distal pollical phalanx confirms the presence of a human-like flexor pollicis longus muscle in A. afarensis. The new fossils include the first complete fourth metatarsal known for A. afarensis. This specimen exhibits the dorsoplantarly expanded base, axial torsion and domed head typical of humans, revealing the presence of human-like permanent longitudinal and transverse arches and extension of the metatarsophalangeal joints as in human-like heel-off during gait. The new Hadar postcranial fossils provide a more complete picture of postcranial functional anatomy, and individual and temporal variation within this sample. They provide the basis for further in-depth analyses of the behavioral and evolutionary significance of A. afarensis anatomy, and greater insight into the biology and evolution of these early hominins.
KW - Afar
KW - Axial skeleton
KW - Bipedalism
KW - Foot
KW - Limbs
KW - Pliocene hominins
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U2 - 10.1016/j.jhevol.2011.11.012
DO - 10.1016/j.jhevol.2011.11.012
M3 - Article
C2 - 22652491
AN - SCOPUS:84863503272
SN - 0047-2484
VL - 63
SP - 1
EP - 51
JO - Journal of human evolution
JF - Journal of human evolution
IS - 1
ER -