White Heather E, Tucker Abigail S, Goswami Anjali
Centre for Craniofacial and Regenerative Biology, King's College London, Great Maze Pond, London SE1 9RT, United Kingdom.
Science Department, Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom.
Zool J Linn Soc. 2024 May 24;203(2):zlae060. doi: 10.1093/zoolinnean/zlae060. eCollection 2025 Jan 31.
Cranial sutures, both open and closed, support a myriad of skull functions, including redistributing strain, accommodating brain expansion, supporting cranial bone growth, and protecting the brain. Thus, variation in the degree, timing, and pattern of suture fusion has functional implications. Using a comparative ontogenetic framework across Mammalia, we quantified degree and pattern of suture fusion through ontogeny for 22 mammalian species ( = 165). Suture closure was scored on a discrete scale for 31 cranial sutures and used to calculate closure scores for individual sutures and specimens. Ancestral state estimations found the degree of ancestral marsupial fusion to be more derived, differing from both the ancestral placental and ancestral therian. The average placental pattern followed the Krogman pattern of suture fusion (cranial vault, cranial base, circum-meatal, palatal, facial, and cranio-facial), whereas marsupials showed a distinct pattern. We propose a new pattern of suture fusion for marsupials: vault, cranio-facial, facial, circum-meatal, palate, cranial base. Delayed fusion of the marsupial cranial base is hypothesized here to support prolonged postnatal growth of the marsupial brain. Collectively, our study has identified a clear marsupial-placental dichotomy in the degree, timing, and pattern of suture fusion, with implications for understanding skull function and ontogeny.
颅缝，无论开放还是闭合，都支持着众多颅骨功能，包括重新分配应变、适应大脑扩张、支持颅骨生长以及保护大脑。因此，缝融合的程度、时间和模式的变化具有功能意义。我们使用一个跨哺乳动物的比较个体发育框架，通过个体发育过程对22种哺乳动物（ = 165）的缝融合程度和模式进行了量化。对31条颅缝的缝闭合情况进行了离散评分，并用于计算单个缝和标本的闭合分数。祖先状态估计发现，有袋类祖先的融合程度更为特化，与胎盘类祖先和兽类祖先均不同。胎盘类的平均模式遵循克罗格曼缝融合模式（颅顶、颅底、颞骨周围、腭部、面部和颅面部），而有袋类则呈现出独特的模式。我们提出了一种新的有袋类缝融合模式：颅顶、颅面部、面部、颞骨周围、腭部、颅底。在此假设，有袋类颅底的延迟融合有助于支持有袋类大脑出生后的长期生长。总体而言，我们的研究在缝融合的程度、时间和模式方面明确了有袋类和胎盘类之间的二分法，这对于理解颅骨功能和个体发育具有重要意义。
