Affiliation:
1. Department of Biological Sciences, Clemson University, Clemson, SC 29634USA
Abstract
SUMMARYSalamanders are often used as representatives of the basal tetrapod body plan in functional studies, but little is known about the loads experienced by their limb bones during locomotion. Although salamanders' slow walking speeds might lead to low locomotor forces and limb bone stresses similar to those of non-avian reptiles, their highly sprawled posture combined with relatively small limb bones could produce elevated limb bone stresses closer to those of avian and mammalian species. This study evaluates the loads on the femur of the tiger salamander (Ambystoma tigrinum) during terrestrial locomotion using three-dimensional measurements of the ground reaction force (GRF) and hindlimb kinematics, as well as anatomical measurements of the femur and hindlimb muscles. At peak stress (29.8±2.0% stance), the net GRF magnitude averaged 0.42 body weights and was directed nearly vertically for the middle 20–40% of the contact interval, essentially perpendicular to the femur. Although torsional shear stresses were significant (4.1±0.3 MPa), bending stresses experienced by the femur were low compared with other vertebrate lineages (tensile: 14.9±0.8 MPa; compressive: –18.9±1.0 MPa), and mechanical property tests indicated yield strengths that were fairly standard for tetrapods (157.1±3.7 MPa). Femoral bending safety factors (10.5) were considerably higher than values typical for birds and mammals, and closer to the elevated values calculated for reptilian species. These results suggest that high limb bone safety factors may have an ancient evolutionary history, though the underlying cause of high safety factors (e.g. low limb bone loads, high bone strength or a combination of the two) may vary among lineages.
Publisher
The Company of Biologists
Subject
Insect Science,Molecular Biology,Animal Science and Zoology,Aquatic Science,Physiology,Ecology, Evolution, Behavior and Systematics
Cited by
19 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献