Allometry and Evolution of Neurocranial Narrowness Across Nonhuman Anthropoid Primates

We did not identify a unified neurocranial narrowness allometry across platyrrhines or across anthropoids collectively. Nonetheless, reduced narrowness occurred parallel to the evolution of increased body size in catarrhines, atelids, and pitheciids, suggesting that larger body size may mitigate constraints on neurocranial shape responsible for narrow neurocrania in small-bodied fossil anthropoids, which have been retained only in small-bodied platyrrhines. Feeding adaptations and brain size also provide potential explanations for neurocranial narrowness variation in some clades.