Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs
- Published
- Accepted
- Subject Areas
- Animal Behavior, Evolutionary Studies, Paleontology
- Keywords
- Dinosaur, Cartilage, Neck, Cervical vertebra, Sauropod, Posture
- Copyright
- © 2014 Taylor
- 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. Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs. PeerJ PrePrints 2:e588v2 https://doi.org/10.7287/peerj.preprints.588v2
Abstract
Attempts to reconstruct the neutral neck posture of sauropod dinosaurs, or indeed any tetrapod, are doomed to failure when based only on the geometry of the bony cervical vertebrae. The thickness of the articular cartilage between the centra of adjacent vertebrae affects posture. It extends (raises) the neck by an amount roughly proportional to the thickness of the cartilage. It is possible to quantify the angle of extension at an intervertebral joint: it is roughly equal, in radians, to the cartilage thickness divided by the height of the zygapophyseal facets over the centre of rotation. Applying this formula to published measurements of well-known sauropod specimens suggests that if the thickness of cartilage were equal to 4.5%, 10% or 18% of centrum length, the neutral pose of the Apatosaurus louisae holotype CM 3018, would be extended by an average of 5.5, 11.8 or 21.2 degrees, respectively, at each intervertebral joint. For the Diplodocus carnegii holotype CM 84, the corresponding angles of additional extension are even greater: 8.4, 18.6 or 33.3 degrees. The neutral postures calculated for 10% cartilage – the most reasonable estimate – appear outlandish, but it must be remembered that these would not have been the habitual life postures, because animals habitually extend the base of their neck and flex the anterior part, yielding the distinctive S-curve most easily seen in birds.
Author Comment
I revised the manuscript in response to three very helpful reviews (four if you count the handling editor's comments). This version, which I have also resubmitted to the journal, is the result.