DOI: 10.5061/dryad.x0k6djhhg
title: Supplementary Information for Biogeography a key influence on distal forelimb variation in horses through the Cenozoic

description: Locomotion in terrestrial tetrapods is reliant on interactions between
 distal limb bones (e.g. metapodials and phalanges). The
 metapodial-phalangeal joint in horse (Equidae) limbs is highly
 specialised, facilitating vital functions (shock absorption; elastic
 recoil). While joint shape has changed throughout horse evolution,
 potential drivers of these modifications have not been quantitatively
 assessed. Here, I examine the morphology of the forelimb
 metacarpophalangeal (MCP) joint of horses and their extinct kin
 (palaeotheres) using geometric morphometrics and disparity analyses,
 within a phylogenetic context. I also develop a novel alignment protocol
 that explores magnitude of shape change through time, correlated against
 body mass and diet. MCP shape was poorly correlated with mass or diet
 proxies, although significant temporal correlations were detected at 0–1
 Ma intervals. A clear division was recovered between New and Old World
 hipparionin MCP morphologies. Significant changes in MCP disparity and
 high rates of shape divergence were observed during the Great American
 Biotic Interchange, with the MCP joint becoming broad and robust in two
 separate monodactyl lineages, possibly exhibiting novel locomotor
 behaviour. This large scale study of MCP joint shape demonstrates the
 apparent capacity for horses to rapidly change their distal limb
 morphology to overcome discrete locomotor challenges in new
 habitats. 
description: Supplementary information linked to the article,
 including: Word document containing: Laser Scanner
 details - Phylogenetic Reconstruction sources - Temporal ranges - Landmark
 Placements -  Hypothetical ancestral fetlock generation - Iterative OPA
 Alignments - Rates of Trait Evolution - Covariates - Correlation Analyses
 - Species-level OSS Key - Supplementary References. (required software: MS
 Word or similar word processing software) List of
 specimens used in the analysis containing: genus and species -
 institutional location - catalogue number - higher taxonomy (required
 software: Adobe Reader or similar PDF reader) Excel
 spreadsheet / comma separated value (CSV) files containing: 3D landmark
 coordinates for all specimens - Procrustes coordinates averaged per
 species - Univariate covriates - Hypothetical Ancestor raw coordinates
 (required software: MS Excel) MorphoJ file containing:
 Procrustes alignment - PCA plots and scores - Phylogenetic Partial Least
 Squares analysis (required software: MorphoJ) R codes
 ZIP file including: phylogenetic tree (NEXUS file) - Disparity across
 turnover - Correlation Analyses - Ordinary Procrustes Alignment procedure
 - Rates on Branches of tree (required software: R version 3.6.3; unzipping
 software) 3D polygon files for all specimens. 3D models
 used in this study are also available via Morphosource.org, project
 "MacLaren (2021) Equoid metacarpal 3D models" (ID: 0000C1187)
 [link: https://www.morphosource.org/projects/0000C1187?locale=en]. These models will be available for download from Morphosource following reasonable request to the author / institution. (required software: 3D software capably of reading PLY files - examples include Meshlab, Geomagic, 3D viewer, Blender etc.)