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A comparison of metrics for quantifying cranial suture complexity

Research output: Contribution to journalArticle

Heather White, j Clavel, Abigail Tucker, Goswami a

Original languageEnglish
JournalJournal Of The Royal Society Interface
Accepted/In press26 Aug 2020

King's Authors


Cranial sutures play critical roles in facilitating postnatal skull development and function. The diversity of function is reflected in the highly variable suture morphology and complexity. Suture complexity has seldom been studied, resulting in little consensus on the most appropriate approach for comparative, quantitative analyses. Here, we provide the first comprehensive comparison of current approaches for quantifying suture morphology, using a wide range of 2D suture outlines across extinct and extant mammals (n=79). Five complexity metrics (sinuosity index, suture
complexity index [SCI], fractal dimension [FD] box counting, FD madogram and a windowed shorttime Fourier transform with power spectrum density calculation [PSD]) were compared with each other and with the shape variation in the dataset. Analyses of suture shape demonstrate that the primary axis of variation captured attributes other than complexity, supporting the use of a complexity metric over raw shape data for sutural complexity analyses. Each approach captured different aspects of complexity. PSD successfully discriminates different sutural features, such as
looping patterns and interdigitation amplitude and number, while SCI best captured variation in interdigitation number alone. Therefore, future studies should consider the relevant attributes for their question when selecting a metric for comparative analysis of suture variation, function and evolution.

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