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Convex hull estimation of mammalian body segment parameters

Citation

Coatham, Sam; Sellers, William; Püschel, Thomas (2021), Convex hull estimation of mammalian body segment parameters, Dryad, Dataset, https://doi.org/10.5061/dryad.cfxpnvx4k

Abstract

Obtaining accurate values for body segment parameters (BSPs) is fundamental in many biomechanical studies, particularly for gait analysis. Convex hulling, where the smallest-possible convex object that surrounds a set of points is calculated, has been suggested as an effective and time-efficient method to estimate these parameters in extinct animals, where soft tissues are rarely preserved. We investigated the effectiveness of convex hull BSP estimation in a range of extant mammals, to inform the potential future usage of this technique with extinct taxa. Computed tomography scans of both the skeleton and skin of every species investigated were virtually segmented. BSPs (the mass, position of the centre of mass and inertial tensors of each segment) were calculated from the resultant soft tissue segments, while the bone segments were used as the basis for convex hull reconstructions. We performed phylogenetic generalised least squares and ordinary least squares regressions to compare the BSPs calculated from soft tissue segments with those estimated using convex hulls, finding consistent predictive relationships for each body segment. The resultant regression equations can therefore be used with confidence in future volumetric reconstruction and biomechanical analyses of mammals, in both extinct and extant species where such data may not be available.

Methods

A dataset of 35 extant mammal species was collected. Each specimen was CT-scanned, before each scan was processed and segmented in both skin and skeletal forms. These skeletal segments were used to calculate convex hulls surrounding all points on the segment. Body segment parameters (mass, centre of mass and inertial properties) were calculated for each skin and convex hull segment using GaitSym. Regressions were subsequently performed for each segment-BSP combination, to produce predictive equations converting BSP values estimated using convex hulls to those values calculated from skin segments. 

Usage Notes

A ReadMe file is included.

Funding

Manchester Environmental Research Institute

Natural Environment Research Council, Award: NE/R011168/1

Manchester Environmental Research Institute