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Abstract Taxonomic classification is important for understanding the natural world, yet current methods for species assessment often focus on craniodental morphology rather than the entire skeleton. Moreover, it is currently unknown how much variation could, or should, exist intragenerically. Here, we tested whether taxonomy can be accurately predicted based on patterns of morphological variation in macaques (H₁) and whether postcranial bones reflect subgeneric macaque taxonomy similarly, or better, than the cranium (H₂). Data included 3D scans of cranial and postcranial bones for eight macaque species (Macaca arctoides,Macaca fascicularis,Macaca fuscata,Macaca mulatta,Macaca nemestrina,Macaca nigra,Macaca radiata, andMacaca sylvanus). Fixed anatomical and semilandmarks were applied to scans of eight skeletal elements (crania = 45; mandible = 31; scapula = 66; humerus = 38; radius = 33; os coxa = 28; femur = 40; tibia = 40). For each skeletal element, regression analyses were performed to minimize the effects of sexual dimorphism. Between‐groups principal components analysis was used to visualize the major patterns of among‐species morphological variation, while the strength of correct taxon classification was measured with discriminant function analysis. Results suggested accepting the alternate hypothesis that different macaque species can be distinguished morphologically. Both cranial and many postcranial elements appeared to possess a taxonomic signal, and the limb bones—especially the upper limb—are reported to be more useful for taxonomic assessment than previously realized. Theoretically, certain behaviors and/or ecogeographical factors, as well as phylogeny, influenced skeletal morphology in macaques, likely contributing to taxonomic distinctions among different species. 

Abstract ObjectivesMagnitudes of morphological integration may constrain or facilitate craniofacial shape variation. The aim of this study was to analyze how the magnitude of integration in the skull ofMacaca fascicularischanges throughout ontogeny in relation to developmental and/or functional modules. Materials and methodsGeometric morphometric methods were used to analyze the magnitude of integration in the macaque cranium and mandible in 80 juvenile and 40 adultM. fascicularisspecimens. Integration scores in skull modules were calculated using integration coefficient of variation (ICV) of eigenvalues based on a resampling procedure. Resultant ICV scores between the skull as a whole, and developmental and/or functional modules were compared using Mann–WhitneyUtests. ResultsResults showed that most skull modules were more tightly integrated than the skull as a whole, with the exception of the chondrocranium in juveniles without canines, the chondrocranium/face complex and the mandibular corpus in adults, and the mandibular ramus in all juveniles. The chondrocranium/face and face/mandibular corpus complexes were more tightly integrated in juveniles than adults, possibly reflecting the influences of early brain growth/development, and the changing functional demands of infant suckling and later masticatory loading. This is also supported by the much higher integration of the mandibular ramus in adults compared with juveniles. DiscussionMagnitudes of integration in skull modules reflect developmental/functional mechanisms inM. fascicularis. However, the relationship between “evolutionary flexibility” and developmental/functional mechanisms was not direct or simple, likely because of the complex morphology, multifunctionality, and various ossification origins of the skull.