Growth‐related shape changes in the fetal craniofacial complex of humans (Homo sapiens) and pigtailed macaques (Macaca nemestrina): A 3D‐CT comparative analysis

Abstract

This study investigates whether macaques and humans possess a common pattern of relative growth during the fetal period. The fetal samples consist of 16 male pigtailed macaques (mean age, 20.5 gestational weeks) and 17 humans (9 males and 8 females; mean age, 29.5 gestational weeks). For each individual, three-dimensional coordinates of 18 landmarks on the skull were collected from three-dimensional computed tomographic (CT) reconstructed images and two-dimensional CT axial slices. Early and late groups were created from the human (early mean age, 24 weeks, N = 8; late mean age, 34 weeks, N = 9) and macaque samples (early mean age, 17.7 weeks, N = 7; late mean age, 23 weeks, N = 9). Inter- and intraspecific comparisons were made between the early and late groups. To determine if macaques and humans share a common fetal pattern of relative growth, human change in shape estimated from a comparison of early and late groups was compared to the pattern estimated between early and late macaque groups. Euclidean distance matrix analysis was used in all comparisons. Intraspecific comparisons indicate that the growing fetal skull displays the greatest amount of change along mediolateral dimensions. Changes during human growth are primarily localized to the basicranium and palate, while macaques experience localized change in the midface. Interspecific comparisons indicate that the two primate species do not share a common pattern of relative growth, and the macaque pattern is characterized by increased midfacial growth relative to humans. Our results suggest that morphological differences in the craniofacial skeleton of these species are in part established by differences in fetal growth patterns.

Brain expansion and comparative prenatal ontogeny of the non-hominoid primate cranial base

“…Nevertheless, the findings clearly show that prenatal elongation of the non-hominoid primate anterior cranial base is significantly greater than that of the posterior base. This closely matches results from previous investigations of the same series of fetal macaques (Sirianni and Newell-Morris, 1980;Zumpano and Richtsmeier, 2003). Although there are no comparable studies for Alouatta, there seems no reason to doubt the linear growth differences reported here.…”

“…Unfortunately, there are no previous studies of Alouatta that are directly comparable to this study. However, previous investigations of the same macaque series report that the angulation remains stable throughout fetal life (Lestrel and Moore, 1978;Moore, 1978;Sirianni and Newell-Morris, 1980;Zumpano and Richtsmeier, 2003). The inconsistency between their findings and the retroflexion reported here is a concern, especially since Moore and others examined many of the same individual specimens studied here.…”

“…Unlike nasion, foramen caecum does not conflate facial growth patterns with those of the basicranium (Scott, 1958;Hagg et al, 1998; Perillo et al, 2000;McCarthy, 2001). In addition, Lestrel and Moore (1978), and later Zumpano and Richtsmeier (2003), dichotomized their samples into broad age cohorts and then compared the resulting cohort means in order to determine the change in cranial base angle. Their method may have averaged-out the subtle but significant (slope=0.28) intervening changes of cranial base angle seen in the present investigation.…”

Differences in the morphology of the maxillary sinus and roots of teeth between Macaca fuscata and Macaca fuscata yakui determined using cone beam computed tomography

“…Zumpano and Richtsmeier 15) reported that the lower face change rates after inferior zygomatic-maxillary sutures were larger in fetal pigtail macaque at the asterionasterion using 3D CT images. The sexual dimorphism difference with regard to body weight and canine size in primates is related to the polygyny associated with parental investment and various ecological factors 16) .…”

Holes in the head: Evolutionary interpretations of the paranasal sinuses in catarrhines

“…118 Although it is quite common to find morphological variation in samples of individuals, 119 recent studies of postnatal shape trajectories in the craniofacial skeleton point to significant differences among both papionin Old World monkeys (macaques, mangabeys, and baboons) 120 and hominins. 121,122 Thus, in addition to the fact that differences between the craniofacial morphology of humans and nonhuman primates are already evident in fetal stages, 123 these studies indicate that variation in the craniofacial morphology of adult forms of primates is due, in part, to differences in the postnatal ontogenetic shape trajectories. 121 Because the paranasal sinuses, when present, are an inherent part of the facial skeleton, it is most likely that different craniofacial growth patterns are responsible for the variation in the degree of paranasal pneumatization among anthropoids.…”