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KSD-VP-1/1 from Woranso Mille, Ethiopia, does not conform to known Australopithecus afarensis pelvic morphology

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author HaeuslerM., FornaiCinzia, KrennV. A., WebbN. M.,
Project Birth and human evolution - implications from computer-assisted reconstructions
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Original article (peer-reviewed)

Journal American Journal of Physical Anthropology
Volume (Issue) 171
Page(s) 111
Title of proceedings American Journal of Physical Anthropology

Open Access

URL https://onlinelibrary.wiley.com/toc/10968644/2020/171/S69
Type of Open Access Publisher (Gold Open Access)

Abstract

Despite accumulating craniodental evidence for the co-existence of multiple hominin species broadly contemporaneous with Australopithecus afarensis in East Africa, interpretation of morphological variation and sexual dimorphism is more challenging in postcranial fossils commonly attributed to A. afarensis. The 3.6-million-year-old KSD-VP-1/1 skeleton from Woranso-Mille, Ethiopia, is pivotal in this context given its completeness, large body size and purported male sex. The hipbone and sacrum are expanded by numerous matrix-?lled cracks, though plastic deformation is absent. Based on high-resolution CT-scans provided by the Woranso-Mille project we isolated and virtually realigned all bone fragments, using 3D prints as validation. Missing regions of the hipbone were estimated using landmark-based warping methods and A.L. 288-1 (A. afarensis) as a template. Our reconstruction suggests a remarkably long iliac blade and an unusually narrow sacroiliac joint. Both possibly primitive characteristics clearly distinguish KSD-VP-1/1 from other australopithecines. A corresponding Procrustes distance-based pairwise permutation showed that the difference in sacroiliac joint morphology between KSD-VP-1/1 and A.L. 288-1 exceeds 98.5% of pairwise comparisons within our modern human and orangutan sample. In a 3D geometric morphometric analysis of the hipbone based on 24 homologous landmarks and 60 extant humans, 40 chimpanzees, 40 gorillas and 29 orangutans, as well as A.L. 288-1, Sts 14 and StW 431 (both A. africanus), and MH2 (A. sediba), KSD-VP-1/1 plotted at the border of the australopithecine distribution. This discrepancy increased when size-adjusted residuals were used to control for allometric in?uences on shape. These ?ndings might suggest functional and taxonomic diversity within the A. afarensis hypodigm.
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