PMID: 9438835Mar 14, 1998Paper

Effects of speed on the hindlimb kinematics of the lizard dipsosaurus dorsalis

The Journal of Experimental Biology
C Fieler, b

Abstract

Lizards are the most diverse extant lineage of vertebrates believed to have retained the sprawling limb posture of ancestral tetrapods and, although the sprinting speeds of lizards are well documented, quantitative analyses of limb movements are lacking. We therefore examined a wide range of steady running speeds to quantify variation in the kinematics of a morphologically generalized hindlimb in the lizard Dipsosaurus dorsalis. From speeds of 50 to 350 cm s-1, stride length, step length and stride frequency all had significant curvilinear increases from 13.3 to 39.4 cm, from 8.9 to 12.8 cm and from 3.9 to 8.6 Hz, respectively, whereas duty factor (percentage of cycle when foot is on ground) decreased from 63 to 34 % with increased speed. For five standardized speeds ranging from 50 to 250 cm s-1, analyses of variance detected highly significant (P<0.001) effects of speed on 27 out of a total of 46 kinematic variables. The height of the hip at the time of footfall increased significantly with increased speed, whereas the amount of pelvic rotation in the horizontal plane (mean 36 degrees ) per stride was unaffected by speed. The orientation of the long axis of the foot changed by nearly 50 degrees with increased speed such that ...Continue Reading

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