DOI: 10.5061/dryad.83bk3j9x2
title: Electronic supporting information for: Evolution of posture in amniotes–diving into the trabecular architecture of the femoral head

description: Extant amniotes show remarkable postural diversity. Broadly speaking,
 limbs with erect (strongly adducted, more vertically oriented) posture are
 found in mammals that are particularly heavy (graviportal) or show good
 running skills (cursorial), while crouched (highly flexed) limbs are found
 in taxa with more generalized locomotion. In Reptilia, crocodylians have a
 “semi-erect” (somewhat adducted) posture, birds have more crouched limbs
 and lepidosaurs have sprawling (well-abducted) limbs. Both synapsids and
 reptiles underwent a postural transition from sprawling to more erect
 limbs during the Mesozoic Era. In Reptilia, this postural change is
 prominent among archosauriforms in the Triassic Period. However, limb
 posture in many key Triassic taxa remains poorly known. In Synapsida, the
 chronology of this transition is less clear, and competing hypotheses
 exist. On land, the limb bones are subject to various stresses related to
 body support that partly shape their external and internal morphology.
 Indeed, bone trabeculae (lattice-like bony struts that form the spongy
 bone tissue) tend to orient themselves along lines of force. Here, we
 study the link between femoral posture and the femoral trabecular
 architecture using phylogenetic generalized least squares. We show that
 microanatomical parameters measured on bone cubes extracted from the
 femoral head of a sample of amniote femora depend strongly on body mass,
 but not on femoral posture or lifestyle. We reconstruct ancestral states
 of femoral posture and various microanatomical parameters to study the
 “sprawling-to-erect” transition in reptiles and synapsids, and obtain
 conflicting results. We tentatively infer femoral posture in several
 hypothetical ancestors using phylogenetic flexible discriminant analysis
 from maximum likelihood estimates of the microanatomical parameters. In
 general, the trabecular network of the femoral head is not a good
 indicator of femoral posture. However, ancestral state reconstruction
 methods hold great promise for advancing our understanding of the
 evolution of posture in amniotes.
description: # Gônet et al. Evolution of posture in amniotes–Diving into the trabecular
 architecture of the femoral head. Electronic supporting information.
 [Access this dataset on Dryad](10.5061/dryad.83bk3j9x2) This dataset
 contains the information files that support the results presented in the
 study by Gônet, J., Laurin, M., & Hutchinson, J. R. ## Description
 of the data and file structure The file entitled Phylogenetic\_Trees.tre
 contains the 100 phylogenetic trees used in the study. The trees are in
 Newick (parenthetic) format. The file can be opened and modified as a .txt
 file, but is intended for use in R as part of the analyses presented in
 the study. The file entitled Supporting\_Information.pdf contains the
 supplementary figures and tables mentioned in the main text of the study.
 The file entitled Bone\_Cubes.rar contains the new microanatomical data
 obtained to complement the original data from Doube et al. (2011). The
 archive contains 25 folders corresponding to the 25 amniote species
 studied for which new microanatomical data are available. These are
 provided as .tif files. The name of each folder is determined as follows:
 Genus\_species\_identifier.