Meeting Abstract
69.6 Monday, Jan. 6 09:15 Body mass, limb length, and limb mass and their role in locomotor specializations in terrestrial and semi-terrestrial mammals KILBOURNE, BM; Friedrich-Schiller-Universität Jena brandon.kilbourne@uni-jena.de
Traditionally, broader, comparative assessments of limb specializations in terrestrial and semi-terrestrial mammals have focused on osteological measurements, most notably limb proportions. However, the mass of limbs and their constituent segments, which are inclusive of both hard and soft tissues, may also offer insight into the functional specializations of mammalian limbs, as relative muscle and bone size, as well as limb mass distribution, vary according to limb function. I performed a principal components analysis using data on body mass and fore- and hindlimb length and mass from 44 species of terrestrial mammals to determine whether whole limb design differentiates species according to the following specializations: cursorial, natatorial, fossorial, and scansorial. PC-1 represents overall species size in terms of all five variables. Though PC-1 represents 98% of the cumulative variance, PC-2 represents limb length relative to body and limb mass. PC-3 represents a trade-off between fore- and hindlimb mass. At one extreme of PC-3 are taxa possessing relatively more massive and longer forelimbs for digging or capturing/restraining prey, whereas at the other extreme of PC-3 are taxa with forelimbs reduced in length or mass relative to hindlimbs. Interestingly, in a morphospace plot of PC-1 vs. PC-2, cursorial taxa are separate from non-cursorial taxa, which all tend to overlap. The occupation by cursors of a distinct and separate region of morphospace suggests that body size and the length of limbs relative to mass traits contribute to the overall morphology of taxa that are specialized for locomoting at high speeds or long distances. Thus in order to better understand how limb design varies among different mammalian species, mass traits should be investigated alongside purely osteological traits.
