The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


Mandibular variation in early Homo and Au. sediba

LAUREN SCHROEDER1, KEELY CARLSON2, DARRYL J. DE RUITER2 and REBECCA R. ACKERMANN1.

1Department of Archaeology, University of Cape Town, 2Department of Anthropology, Texas A&M University

Friday 9:30-9:45, Grand Ballroom II Add to calendar

The composition of the enigmatic early Homo hypodigm has been a central topic in the paleoanthropological literature for more than 50 years. Recently, the expansion of early Homo fossil samples and the announcement of new contemporaneous species have added to an ever intensifying debate surrounding the phylogenetic relationships among early members of our genus, renewing the idea of a diverse lineage, morphologically, temporally and geographically. The boundaries between specimens, populations and species have been further blurred with the new finding of Au. sediba, given the mosaic of Homo-like and Australopithecus-like traits displayed amongst the adult and juvenile individuals of this species.

Here we evaluate morphological diversity in early Homo and Au. sediba mandibular specimens, paying particular attention to the evolutionary positioning of the latter. Three-dimensional scanner and conventional morphometric data are collected from specimens from southern and eastern Africa, including an extant ontogenetic sample for investigation of variation between juveniles and adults of the same species. To provide context, numerous robust and gracile australopith mandibles are incorporated due to their temporal and spatial correspondence. Variance/covariance matrices from extant hominoids are used to calculate inter-individual scaled Mahalanobis’ Distances between these specimens to assess morphological relationships. EDMA is performed on mean forms of each sample and a series of PCoord analyses is used to visualize differences between juvenile and adult individuals (i.e. species growth trajectories). Results highlight a possible separation of east and South African early Homo specimens, and a unique growth trajectory for Au. sediba, neither australopith-like nor Homo-like.

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