Cranial synchondroses of primates at birth.
Development; Craniofacial; Perinatal; Chondrocranium
Cranial synchondroses are cartilaginous joints between basicranial bones or between basicranial bones and septal cartilage, and have been implicated as having a potential active role in determining craniofacial form. However, few studies have examined them histologically. Using histological and immunohistochemical methods, we examined all basicranial joints in serial sagittal sections of newborn heads from nine genera of primates (five anthropoids, four strepsirrhines). Each synchondrosis was examined for characteristics of active growth centers, including a zonal distribution of proliferating and hypertrophic chondrocytes, as well as corresponding changes in matrix characteristics (i.e., density and organization of type II collagen). Results reveal three midline and three bilateral synchondroses possess attributes of active growth centers in all species (sphenooccipital, intrasphenoidal, presphenoseptal). One midline synchondrosis (ethmoseptal) and one bilateral synchondrosis (alibasisphenoidal, ABS) are active growth centers in some but not all newborn primates. ABS is oriented more anteriorly in monkeys compared to lemurs and bushbabies. The sphenoethmoidal synchondrosis (SES) varies at birth: in monkeys, it is a suture-like joint (i.e., fibrous tissue between the two bones); however, in strepsirrhines, the jugum sphenoidale is ossified while the mesethmoid remains cartilaginous. No species possesses a SES that has the organization of a growth plate. Overall, our findings demonstrate that only four midline synchondroses have the potential to actively affect basicranial angularity and facial orientation during the perinatal timeframe, while the SES of anthropoids essentially transitions toward a "suture-like" function, permitting passive growth postnatally. Loss of cartilaginous continuity at SES and reorientation of ABS distinguish monkeys from strepsirrhines. This article is protected by copyright. All rights reserved. (This article is protected by copyright. All rights reserved.)
Smith TD;Reynolds RL;Mano N;Wood BJ;Oladipupo L;Hughes GK;Corbin HM;Taylor J;Ufelle A;Burrows AM;Durham E;Vinyard CJ;Cray JJ;DeLeon VB
Anatomical Record
2020
2020-10-04
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journalArticle
<a href="http://doi.org/10.1002/ar.24521" target="_blank" rel="noreferrer noopener">10.1002/ar.24521</a>
Palate Variation and Evolution in New World Leaf-Nosed and Old World Fruit Bats (Order Chiroptera)
cranial shape; Craniofacial; evolution; Evolutionary Biology; feeding-behavior; fluctuating asymmetry; food hardness; fossil; geometric; Integration; Modularity; Modularity; morphological integration; Morphometrics; Morphometrics; patterns; Phyllostomid; Pteropodid; record; skull morphology
Two bat families, the leaf-nosed (Phyllostomidae) and fruit bats (Pteropodidae), have independently evolved the ability to consume plant resources. However, despite their similar ages, species richness and the strong selective pressures placed on the evolution of skull shape by plant-based foods, phyllostomids display more craniofacial diversity than pteropodids. In this study, we used morphometrics to investigate the distribution of palate variation and the evolution of palate diversity in these groups. We focused on the palate because evolutionary alterations in palate morphology are thought to underlie much feeding specialization in bats. We hypothesize that the distribution of palate variation differs in phyllostomids and pteropodids, and that the rate of palate evolution is higher in phyllostomids than pteropodids. The results suggest that the overall level of palate integration is higher in adult populations of pteropodids than phyllostomids but that the distribution of palate variation is otherwise generally conserved among phyllostomids and pteropodids. Furthermore, the results are consistent with these differences in palate integration likely having a developmental basis. The results also suggest that palate evolution has occurred significantly more rapidly in phyllostomids than pteropodids. These findings are consistent with a scenario in which the greater integration of the pteropodid palate has limited its evolvability.
Sorensen D W; Butkus C; Cooper L N; Cretekos C J; Rasweiler J J; Sears K E
Evolutionary Biology
2014
2014-12
Journal Article
<a href="http://doi.org/10.1007/s11692-014-9291-6" target="_blank" rel="noreferrer noopener">10.1007/s11692-014-9291-6</a>