Scaling and functional morphology in strigiform hind limbs.
Strigiformes are an order of raptorial birds consisting exclusively of owls: the Tytonidae (barn owls) and the Strigidae (true owls), united by a suite of adaptations aiding a keen predatory lifestyle, including robust hind limb elements modified for grip strength. To assess variation in hind limb morphology, we analysed how the dimensions of the major hind limb elements in subfossil and modern species scaled with body mass. Comparing hind limb element length, midshaft width, and robusticity index (RI: ratio of midshaft width to maximum length) to body mass revealed that femoral and tibiotarsal width scale with isometry, whilst length scales with negative allometry, and close to elastic similarity in the tibiotarsus. In contrast, tarsometatarsus width shows strong positive allometry with body mass, whilst length shows strong negative allometry. Furthermore, the tarsometatarsi RI scales allometrically to mass0.028, whilst a weak relationship exists in femora (mass0.004) and tibiotarsi (mass0.004). Our results suggest that tarsometatarsi play a more substantial functional role than tibiotarsi and femora. Given the scaling relationship between tarsometatarsal width and robusticity to body mass, it may be possible to infer the body mass of prehistoric owls by analysing tarsometatarsi, an element that is frequently preserved in the fossil record of owls.
School of Earth Sciences, University of Bristol, Bristol, United Kingdom.
Meena A
MA
Madan
School of Earth Sciences, University of Bristol, Bristol, United Kingdom.
Emily J
EJ
Rayfield
School of Geosciences, University of South Florida, Tampa, Florida, USA.|Center for Virtualization and Applied Spatial Technologies, University of South Florida, Tampa, Florida, USA.
Jen A
JA
Bright
D000818:Animals; D005269:Femur / Q000033:anatomy & histology; D006614:Hindlimb / Q000033:anatomy & histology* / Q000502:physiology*; D020305:Strigiformes / Q000033:anatomy & histology* / Q000502:physiology*