Meeting Abstract

93.7  Monday, Jan. 6 15:00  Modulation of strain magnitude in the limb bones of tetrapods AIELLO, B.R.*; IRIARTE-DIAZ, J.; BLOB, R.W.; BUTCHER, M.T.; ESPINOZA, N.R.; MAIN, R.P; ROSS, C.F.; Univ. of Chicago; Univ. of Chicago; Clemson Univ.; Youngstown State Univ.; Clemson Univ.; Purdue Univ.; Univ. of Chicago braiello@uchicago.edu

Variation in bone strain magnitude can be correlated with variation in duration of the load cycle, load rate, or both. In the feeding system, mammalian mandibular strain magnitude is correlated strongly with strain rate, and only weakly with load duration. The goal of this study was to expand the evaluation of strain magnitude modulation to the tetrapod locomotor system. We performed new analyses of strain data that had been collected from the limb bones of terrestrial vertebrates from a range of tetrapod lineages employing different locomotor habits (frog, turtle, tegu lizard, emu, goats, and opossums). We hypothesized that strain magnitude is correlated with strain rate in limb bones, as in mandibles, and that the modulation of bone strain magnitude primarily by strain rate is therefore a common feature of the bones of all tetrapods. Bivariate correlations across all study taxa and all bones, including the femur, tibiotarsus, and radius reveal that principal strain magnitudes are always significantly correlated with strain rate but usually not correlated with the duration of the load cycle. Furthermore, in multivariate analyses, beta coefficients for load rate were usually twice those calculated for load duration. These results suggest that, across all taxa and all bones studied, variation in strain magnitude is best explained by variation in strain rate and not the duration of the load cycle. In combination with the results from mammalian mandibles, this broad survey across vertebrates suggests that strain modulation by loading rate is a common feature of all vertebrate bone.