Meeting Abstract
Cranial variation across mammals is vast and reflects their ecological diversification. Sutures perform many different functions in cranial development and function, from permitting craniofacial growth to facilitating feeding. Diversity of function is reflected in the highly variable morphology and complexity. Phenotypic variation across species is generally only studied at a fully mature ‘adult’ state, with limited comparison on how such variation develops. The lack of comparative developmental data, for both cranial and suture morphology, is striking, considering the intrinsic link between evolution and development. As part of a larger study of suture and skull development and morphology in a comparative framework of mammals, we here quantify suture morphology across ontogeny, with microCT scans spanning late prenatal foetuses to adult stages for representative species of Laurasiatheria including Manis tricuspis and Talpa europaea. A 2D test dataset of extinct and extant mammals (n=79) was created to compare available methods for quantifying suture morphology, by means of complexity. From the 2D suture images, 500 semilandmarks were resampled in the R package Stereomorph to capture suture shape data. Complexity methods (fractal dimension and short-time Fourier transform with power spectrum density) were applied to the test dataset. Both methods were reliable for simpler sutures, but power spectrum density was more sensitive at detecting differences in sutures with complex morphology. Following this result, we quantified suture complexity and morphology across representative species of Laurasiatheria in an ontogenetic framework, by applying the tested power spectrum density method, with the goal to understanding how development generates suture morphological disparity.
