Ontogenetic scaling patterns and functional anatomy of the pelvic limb musculature in emus (Dromaius novaehollandiae)
- Published
- Accepted
- Subject Areas
- Bioengineering, Developmental Biology, Evolutionary Studies, Paleontology, Anatomy and Physiology
- Keywords
- tendon, ratite, : muscle, bone, scaling, Palaeognathae, emu, biomechanics, locomotion
- Copyright
- © 2014 Lamas et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2014. Ontogenetic scaling patterns and functional anatomy of the pelvic limb musculature in emus (Dromaius novaehollandiae) PeerJ PrePrints 2:e508v1 https://doi.org/10.7287/peerj.preprints.508v1
Abstract
Emus (Dromaius novaehollandiae) are exclusively terrestrial, bipedal and cursorial ratites with some similar biomechanical characteristics to humans. Their growth rates are impressive as their body mass increases eighty-fold from hatching to adulthood whilst maintaining the same mode of locomotion throughout life. These ontogenetic characteristics stimulate biomechanical questions about the strategies that allow them to cope through these changes. To answer such questions, in this study we have collected pelvic limb anatomical data (muscle architecture, tendon length, tendon mass and bone lengths) and calculated muscle physiological cross sectional area (PCSA) and average tendon cross sectional area from emus across an ontogenetic series (n=17, body masses from 3.6 to 42 kg). The data were analysed by reduced major axis regression to determine scaling relationships with body mass. Muscle mass and PCSA showed a marked trend towards positive allometry (26 and 27 out of 34 muscles respectively) and fascicle length showed a more mixed scaling pattern. The long tendons of the main digital flexors scaled with positive allometry for all characteristics whilst other tendons demonstrated a less clear scaling pattern. Finally, the two longer bones of the limb (tibiotarsus and tarsometatarsus) also exhibited positive allometry for length and the other two (femur and first phalanx of the pes) had trends towards isometry. These results indicate that emus increase their muscle force-generating capacities, as well as potentially increasing the force-sustaining capacities of their tendons, as they grow. Furthermore, we have clarified anatomical descriptions and provided illustrations of the pelvic limb muscle-tendon units in emus.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Supplementary information: Raw Data (five worksheets)
Raw data on which Statistical Analysis was performed. Five separate worksheets.