DOI: 10.5061/dryad.bcc2fqz9w
title: Locomotion and paleoclimate explain the re-evolution of quadrupedal body form in Brachymeles lizards

description: Evolutionary reversals, including re-evolution of lost structures, are
 commonly found in phylogenetic studies. However, we lack an understanding
 of how these reversals happen mechanistically. A snake-like body form has
 evolved many times in vertebrates, and occasionally, a quadrupedal form
 has re-evolved, including in Brachymeles lizards. We use body form and
 locomotion data for species ranging from snake-like to quadrupedal to
 address how a quadrupedal form could re-evolve. We show that large,
 quadrupedal species are faster at burying and surface locomotion than
 snake-like species, indicating a lack of expected performance trade-off.
 Species with limbs use them while burying, suggesting that limbs are
 useful for burying in wet, packed substrates. Paleoclimatological data
 suggest that Brachymeles originally evolved a snake-like form under a
 drier climate likely with soil in which it was easier to dig. The
 quadrupedal clade evolved as the climate became humid, where limbs and
 large size facilitated fossorial locomotion in packed soils.
description: The dataset was primarily collected in the field, from high-speed
 videos of animals moving on the surface and burying into a coarse and a
 fine substrate. Force readings were also recorded in the field, as were
 soil load-bearing capacities and soil moisture. Morphometrics were
 collected form the preserved specimens. Dataset processing consisted of
 taking species averages of individual-level data for comparative
 analyses. The dataset contains several spreadsheets. It
 contains species means for 14 species of lizards
 (13 <em>Brachymeles</em> skinks, plus <em>Lygosoma
 bowringii</em>). These data are morphometric (body proportions and
 measurements), ecological (soil moisture and load-bearing capacity),
 surface locomotion (running or crawling on coarse and fine substrates),
 buring locomotion (in coarse and fine substrates), and burrowing force
 data. There is also a dataset of head length for 40 species
 of <em>Brachymeles</em>, individual morphometrics for the
 animals used in locomotion work (161 individuals distributed across the
 species), individual burrowing force data for 268 trails, individual-level
 surface locomotion data for 307 trials, and individual-level burying data
 for 297 trials. The individual-level data were used to calculate the
 species mean data. Additionally, there is a text file
 containing the two phylogenies that we used to analyze the data. One
 phylogeny contains 40 species of <em>Brachymeles</em> and was
 used with the head length data for the same number of species. The other
 phylogeny contains the 13 species of <em>Brachymeles</em>,
 plus <em>Lygosoma bowringii</em>). Finally,
 there is a text file containing R code used to conduct the analyses and
 construct the figures for the manuscript.
description: Everything needed to use the data is included in a single Excel
 file. There are several data spreadsheets, corresponding to the above
 description. Each spreadsheet also has a readme sheet included that
 explains each variable with a description and units of
 measurement.