DOI: 10.5061/dryad.2547d7wx9
title: Data from: Origins of mammalian vertebral function revealed through digital bending experiments

description: Unravelling the functional steps that underlie major transitions in the
 fossil record is a significant challenge for biologists due to the
 difficulties of interpreting functional capabilities of extinct organisms.
 New computational modelling approaches provide exciting avenues for
 testing function in the fossil record. Here we conduct digital bending
 experiments to reconstruct vertebral function in non-mammalian synapsids,
 the extinct forerunners of mammals, to provide insights into the
 functional underpinnings of the synapsid-mammal transition. We estimate
 range of motion and stiffness of intervertebral joints in eight
 non-mammalian synapsid species alongside a comparative sample of extant
 tetrapods, including salamanders, reptiles, and mammals. We show that
 several key aspects of mammalian vertebral function evolved outside crown
 Mammalia. Compared to early diverging non-mammalian synapsids, cynodonts
 stabilized the posterior trunk against lateroflexion, while evolving axial
 twisting in the anterior trunk. This was later accompanied by posterior
 sagittal bending in crown mammals, and perhaps even therians specifically.
 Our data also supports the prior hypothesis that functional
 diversification of the mammalian trunk occurred via co-option of existing
 morphological regions in response to changing selective demands. Thus,
 multiple functional and evolutionary steps underlie the origin of
 remarkable complexity of the mammalian backbone.
description: Range of motion of vertebral joints of extant amniotes and
 non-mammalian synapsids based on digital simulation using AutoBend
 software.
description: The enclosed datasets include the data and code required to generate range
 of motion data from digital models of vertebrae using AutoBend (see Jones,
 K. E., R. J. Brocklehurst, and S. E. Pierce. "AutoBend: an automated
 approach for estimating intervertebral joint function from bone-only
 digital models." *Integrative Organismal Biology* 3.1 (2021):
 obab026.) Detailed descriptions of the files are as follows: synapsid
 data.csv - CSV file containing the range of motion data generated in
 AutoBend. Data was generated for each specimen, each joint, and each
 iteration of AutoBend. Parameters that were varied were js (Joint spacing,
 mm), it (intersection threshold, %), and strain (unitless). Data that was
 generated were Tor (ROM in axial rotation, L/R mean), Latero (ROM in
 lateroflexion, L/R mean), Dorso (ROM in dorsoflexion), and Ventro (ROM in
 ventroflexion). ROM data are in degrees of motion. The 'type'
 columns indicate which constraint prevented motion for each itteration of
 AutoBend (e.g., 'intersect' is bony intersection). DORSO,
 VENTRO, and LATERO are the stiffness metrics which were calculated as
 described in the methods. synapsid morph data.csv CSV file containing the
 morphological data taken from the vertebrae, used for the stiffness
 calculation. Centrum and arch measurements are presented for each joint,
 where CL (centrum length) and ArchH (arch height) are the mean of the
 anterior and posterior vertebra. Measurements are in mm. Wrapper_vert
 bending_synapsids.PY Wrapper python code for operating AutoBend through
 MayaPy. This code applies AutoBend to each specimen and specifies the
 parameters used, as well as generating the results file. Use this file to
 specify the locations of your models and where results should be saved.
 Mayapy_synapsids.txt The code used to run Mayapy from the command line.
 This allows AutoBend to run automatically without directly opening Maya,
 and is much faster as the graphics interface is not needed. This code
 directs Mayapy to the python wrapper code above which contains details of
 how AutoBend should be run. AutoBend_Plotting_Functions.R A series of R
 functions used to process the data generated by AutoBend in R. These
 include functions which read and reformat the data, as well as plotting
 functions.