Functional interpretations of orbital convergence and enlargement only suggest that basal primates were nocturnal if these features were present in basal primates. The last common ancestor of primates is not known from fossil evidence, and nor are their immediate outgroups. Consequently, the assumption that basal primates had orbital apertures that were convergent and enlarged rests on interpretation of the available evidence from fossils and extant taxa.
The objectives of this study are: (a) to document the relationship between eye size and shape, and activity patterns in extant primates; (b) to document the relationships between eye size and shape, and activity patterns in extant amniotes and use these data to interpret primate eye shape; and (c) to use orbit shape data to reconstruct activity pattern in fossil primates.
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