DOI: 10.5061/dryad.14mb6
title: Data from: The evolution of bipedal running in lizards suggests a consequential origin may be exploited in later lineages.

description: The origin of bipedal locomotion in lizards is unclear. Modeling studies
 have suggested that bipedalism may be an exaptation, a byproduct of
 features originally designed to increase maneuverability, which were only
 later exploited. Measurement of the body center of mass (BCOM) in 124
 species of lizards confirms a significant rearward shift among bipedal
 lineages. Further racetrack trials showed a significant acceleration
 threshold between bipedal and quadrupedal runs. These suggest good general
 support for a passive bipedal model, in which the combination of these
 features lead to passive lifting of the front of the body. However,
 variation in morphology could only account for 56% of the variation in
 acceleration thresholds, suggesting that dynamics have a significant
 influence on bipedalism. Deviation from the passive bipedal model was
 compared with node age, supporting an increase in the influence of
 dynamics over time. Together, these results show that bipedalism may have
 first arisen as a consequence of acceleration and a rearward shift in the
 BCOM, but subsequent linages have exploited this consequence to become
 bipedal more often, suggesting that bipedalism in lizards may convey some
 advantage. Exploitation of bipedalism was also associated with increased
 rates of phenotypic diversity, suggesting exploiting bipedalism may
 promote adaptive radiation.
description: Clemente_Supp_data1Clemente_Supp_data1.csv contains data for the horizontal body center of mass and snout vent length for 124 species of lizards. Species names are as formatted in the Pyron et al. (2013) phylogeny. BCOM.hip represents the mean horizontal position of the body center of mass forward from the hip. SVL is the mean snout to vent length for each species measured. Two additional columns classify bipedal locomotion. Column 4 (bipedal) was used in the study and is divided into species for which bipedal locomotion has been observed (yes), with all other species being placed in the unknown category (unknown). Column 5 (bi.cat) is similar with the exception that species are divided into bipedal, where bipedalism is observed (yes), where only quadrupedal locomotion was observed after high speed filming and observation (no), and unknown where it is ambiguous (unknown).Clemente_Supp_data2Clemente_Supp_data2.csv contains accelerations for bipedal, quadrupedal and transitional strides for each species. Column 1 contain species names, formatted as in the Pyron et al. (2013) phylogeny. Column 2 contains mean acceleration during the stride. Column 3 contains the gait category for each stride as quadrupedal (0), transitional (0.5) or bipedal (1.0).Clemente_Supp_data3Clemente_Supp_data3.csv contains the stride kinematics used to determine predicted threshold kinematics for each species. Column 1 contain species names, formatted as in the Pyron et al. (2013) phylogeny. Column 2 contain the average position of the foot relative to the hip during the stance phase (xfh). Column 3 contains the average hip height during the stance phase used to approximate the vertical COM (ybc). Column 4 contains hind limb length (HLL) used to standardize kinematics for size. Column 5 contains the horizontal BCOM forward of the hip (BCOM). Pyron, R. A., F. T. Burbrink, and J. J. Wiens. 2013. A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC evolutionary biology 13:93.