Open AccessTorsional resistance as a principal component of the structural design of long bones: Comparative multivariate evidence in birds
Author(s) -
De Margerie Emmanuel,
Sanchez Sophie,
Cubo Jorge,
Castanet Jacques
Publication year - 2005
Publication title -
the anatomical record part a: discoveries in molecular, cellular, and evolutionary biology
Language(s) - English
Resource type - Journals
eISSN - 1552-4892
pISSN - 1552-4884
DOI - 10.1002/ar.a.20141
Subject(s) - humerus , torsion (gastropod) , ulna , femur , anatomy , principal component analysis , biology , multivariate statistics , geology , mathematics , statistics , paleontology
Here we study the occurrence of torsion‐resisting morphological and histological features (thin bone walls, circular shaft cross‐section, oblique collagen fibers, and laminar tissue arrangement) in a sample of 168 long bones from wings and legs of 22 bird species. These structural parameters were measured in mid diaphyseal undemineralized cross‐sections and analyzed using uni‐, bi‐, and multivariate (principal components analysis) data analysis techniques. We found that the four variables are significantly and positively correlated, and that covariation between variables accounts for as much as 58% of the total variation. These results suggest that torsion is a main determinant of the macro‐ and microstructural design of long bones in birds. Humerus, ulna, and femur generally possess torsion‐resisting features, while other bones (radius, carpometacarpus, tibiotarsus, tarsometatarsus, and foot phalanx) rather show bending/axial load‐resisting structural properties. These results are congruent with in vivo strain data from the literature, which reported high torsional loading in humerus and ulna during flapping flight, but also in the subhorizontal avian femur during terrestrial locomotion. The precise function of the laminar tissue spatial arrangement, the role of pneumatization, and the influence of flight mode are discussed. © 2004 Wiley‐Liss, Inc.