Anthropology, University of Massachusetts, Amherst
Thursday All day, Clinch Concourse
A prior study of primate cranial diversity has suggested that strepsirrhines show less variation in cranial morphology than catarrhines or platyrrhines, and that strepsirrhine and haplorhine skulls differ fundamentally in morphology. This research did not consider the large-bodied extinct lemurs of Madagascar and thus may not have captured the full range of variation in strepsirrhine crania. To determine whether the implied unparalleled cranial diversity of haplorhines is an artifact of incomplete sampling of strepsirrhines or a real product of the different evolutionary histories of these two clades, we replicated the earlier study, but with an expanded sample for extant species, and the inclusion of extinct lemurs. The extinct lemurs included in our study are Palaeopropithecus kelyus, P. maximus, Megaladapis edwardsi, Hadropithecus stenognathus and Archaeolemur sp. cf. edwardsi.
The cranial morphology of 185 primate taxa was recorded using 3D geometric morphometric techniques. The data were scaled using a Generalized Procrustes Analysis and described via principal components analysis. As in the prior study, the first principal component axis (PCA1) captured the differences between strepsirrhines and haplorhines, but their separation was not nearly as clean. It is the archaeolemurids (Archaeolemur and Hadropithecus), who approach the haplorhines in cranial shape and thus blur the distinctions between the two clades. Inclusion of the extinct lemurs also challenges the second main conclusion of the prior study, i.e., that strepsirrhines and haplorhines differ significantly in their degree of variation. PCA2 captures some of the within-strepsirrhine variation, which does not differ significantly from that of platyrrhines or catarrhines.
Jane Hallenbeck Bemis Endowment for Research in Natural History and the David J. Klingener Endowment Fund.