Sagittal long bone curvature in birds

The maximum sagittal curvature of the long bones (humerus, radius, ulna, fe mur, tibiotarsus and tarsometatarsus) of 45 specimens of birds, belonging t o 36 species, was measured and regressed to the corresponding body mass. Ma thematical results show a tendency of curvature to scale with strong positi ve allometry. Within the species studied, those with more characteristic fl apping flight tend to show relatively low values of curvature in the wing b ones. To check the agreement of the present results with current hypotheses on the origin of long bone curvature, previous results on scaling of myolo gical and cross-sectional parameters in birds are considered. Indirect evid ence suggests that curvature tends to increase bone stresses. Hypotheses th at consider curvature as a consequence of the mechanical action of muscle a llocation and optimization of functional strains are discussed at length. T he possible double genetic-epigenetic determinism of the curvature characte r is evoked. (C) 1999 Editions scientifiques et medicales Elsevier SAS.