Department of Anthropology, Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Paleontology, Richard Gilder Graduate School, American Museum of Natural History, New York Consortium in Evolutionary Primatology
April 16, 2020 10:30AM, Diamond 2
Extant primates differ in their locomotor ontogeny, which may impact the degree of bony shape change through development. Understanding how locomotor ontogeny relates to bony shape change is critical when using juveniles to reconstruct fossil hominin locomotion. This study implements a 3D geometric morphometrics approach to quantify bony shape changes through ontogeny in the capitate, third metacarpal, lateral cuneiform, and third metatarsal of five catarrhine primate taxa: Pan troglodytes, Gorilla gorilla, Pongo pygmaeus, Macaca mulatta, and Homo sapiens. The hypothesis that only taxa with significant locomotor shifts through ontogeny would show significant bony shape change (p<0.05) was not supported. Instead, all taxa except Homo sapiens showed significant changes in shape through ontogeny (quantified as change in ln-Centroid size regressed against change in ln-Procrustes distance, p<0.05), though few pairwise differences were statistically significant between taxa in terms of this change. The hypothesis that Homo would show significantly less integration between the hand and foot in comparison to other taxa also was not supported (p>0.05). These results show that behavioral locomotor shifts do not correlate significantly with degree of shape change any more than other factors through ontogeny. Homo is not unique in its integration pattern between the hand and foot through ontogeny, and therefore patterns of bone development and integration between the hand and foot are likely conserved across this broad range of catarrhine taxa, particularly within the hominoids, supporting prior hypotheses of exaptation in the Homo hand.