DOI: 10.5061/dryad.tx95x6b78
title: Leveraging functional morphology to increase accuracy of body mass estimation: A study using canids

description: Body mass is an important facet of reconstructing the paleobiology of
 fossil species, and has, historically, been estimated from individual
 skeletal measurements. This paper demonstrates the potential advantages of
 estimating body mass using 3D geometric morphometrics on limb bones, which
 allows size to be explicitly contextualized within the functional
 morphology of the animal. Geometric morphometrics of the humerus and femur
 is used to estimate body mass in domestic dogs and wild canids, and the
 resulting estimates are compared to estimates made using limb bone
 dimensions and centroid size. In both groups, 3D methods produced more
 accurate estimates of body mass than linear dimensions. Additionally,
 centroid size was a poor predictor of body mass and should not be
 preferred over linear measurements. The use of 3D methods also reveals
 specific aspects of shape that are associated with different sizes. In
 general, relatively heavier individuals were associated with more robust
 bones and wider articulation sites, as well as larger attachment sites for
 muscles related to flexion and extension of the shoulder and hip joints.
 The body mass equations constructed based on dogs were further evaluated
 on wild canids, as a test of their potential efficacy on fossil canids.
 With some adjustments, the body mass estimation equations made for
 domestic dogs were able to reliably predict the mass of wild canids. These
 equations were then used to estimate body mass for a selection of fossil
 canids: Canis latrans, 16 kg; Aenocyon dirus, 67 kg; Phlaocyon
 multicuspus, 8 kg; and Hesperocyon gregarious, 2.5 kg.
description: # Leveraging functional morphology to increase accuracy of body mass
 estimation: A study using canids
 [https://doi.org/10.5061/dryad.tx95x6b78](https://doi.org/10.5061/dryad.tx95x6b78) ## Description of the data and file structure This data was collected in order to compare the precision of body mass estimation methods, with a focus on testing how 3D geometric morphometric methods compare to element dimensions. ### Files and variables #### File: Supplemental\_data.xlsx **Description:** Raw humeri and femur measurements. Data is split into 3 groups: domestic dogs, wild canids, and fossil canids. Domestic dogs were measured digitally from CT scans in 3D Slicer, wild and fossil canids were measured from physical specimens using calipers. All measurements are in mm. ##### Variables * HGL - humerus greatest length * HDB - humerus distal breadth * HPD - humerus proximal depth * FGL - femur greatest length * FHbr - femur head breadth * FPB - femur proximal breadth * N/A - Not Available. For the CT scanned domestic dogs this occurred when one of the bones was broken or was not completely captured by the scan. For the wild canids, this occurred when the specimen was downloaded from Morphosource and the other corresponding limb was not uploaded. For the fossil canids, this occurred because many of the fossils were found as isolated bones. #### File: Supplemental\_1.docx **Description:** Supplemental figures and tables. * Supplementary Table 1. List of domestic dog breeds used in this study. * Supplementary Table 2. List of wild canids used in this study * Supplementary Table 3. List of fossil specimens used in this study * Supplementary Table 4. Humerus and Femur Landmarks * Supplementary Table 5. Slope and intercept of body mass regressions * Supplementary Table 6. Slope and intercept of logistic regressions on robustness * Supplementary Figure 1. Limb bone morphology of selected dog breeds * Supplementary Figure 2. Linear measurements of the humerus and femur ## Code/software #### File: Bodymass\_supplemental\_code.R **Description:** Example script with representative code for: * Calculating percent prediction error and percent measurement error * Selecting optimal principal components to estimate body mass from shape * Predicting fossil canid body mass * Calculating measurement error * Performing mesh warps to visualize principal components