A CT-based survey of supramedullary diverticula in extant birds
- Published
- Accepted
- Subject Areas
- Evolutionary Studies, Zoology, Anatomy and Physiology
- Keywords
- bird, respiratory system, diverticula, pneumaticity, neural canal, spinal cord, computed tomography, vertebrae, osteological correlates
- Copyright
- © 2018 Atterholt 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
- 2018. A CT-based survey of supramedullary diverticula in extant birds. PeerJ Preprints 6:e27201v2 https://doi.org/10.7287/peerj.preprints.27201v2
Abstract
Birds are unique among extant tetrapods in having pneumatic diverticula of the lungs and air sacs that pass among the viscera and muscles, under the skin, and into the skeleton. In addition, some birds also have supramedullary diverticula inside the neural canal, adjacent to the spinal cord. The anatomy of the supramedullary diverticula has only been documented in a handful of birds to date. Using CT scans, we surveyed the morphology of the supramedullary diverticula in a phylogenetically broad sample of extant birds.
Although supramedullary diverticula are present in some small-bodied taxa such as hummingbirds and pigeons, the diverticula are typically larger and more complex in large forms such as ostriches and pelicans. Absence of these diverticula in loons and grebes is consistent with the lack of skeletal pneumatization in diving birds. Other absences, for example in the kestrel, are less explicable.
When present, the supramedullary diverticula are best developed in presacral vertebrae, but only occasionally present in the synsacrum, and rarely present in caudal vertebrae. In most taxa we have surveyed, the diverticula are not continuous craniocaudally, but exist as separate segments extending fore and aft from each intervertebral joint, as documented by Müller for the pigeon.
Occasionally supramedullary diverticula communicate with interosseous diverticula through foramina in the wall or roof of the neural canal. These foramina are osteological correlates of supramedullary diverticula and allow the presence of these diverticula to be inferred in dry skeletal material and fossil organisms.
Author Comment
This is the abstract for our presentation at the 66th Symposium on Vertebrate Palaeontology and Comparative Anatomy (SVPCA), Manchester, UK, 5th-8th September 2018. Dr. Atterholt presented the talk on the morning of Friday, September 7. We are currently preparing a manuscript on this work for submission to a peer-reviewed journal. This abstract is identical to the previous version. The only difference is that now the slideshow presented in Manchester is attached as a supplementary file.