Cardio-pulmonary anatomy in theropod dinosaurs: Implications from extant archosaurs
Article first published online: 20 MAY 2009
Copyright © 2009 Wiley-Liss, Inc.
Journal of Morphology
Volume 270, Issue 10, pages 1232–1246, October 2009
How to Cite
Quick, D. E. and Ruben, J. A. (2009), Cardio-pulmonary anatomy in theropod dinosaurs: Implications from extant archosaurs. J. Morphol., 270: 1232–1246. doi: 10.1002/jmor.10752
- Issue published online: 14 SEP 2009
- Article first published online: 20 MAY 2009
- Manuscript Accepted: 21 FEB 2009
- Manuscript Revised: 16 FEB 2009
- Manuscript Received: 8 SEP 2008
- theropod heart;
- theropod lung;
- bird lung
Although crocodilian lung and cardiovascular organs are markedly less specialized than the avian heart and lung air-sac system, all living archosaurs possess four-chambered hearts and heterogeneously vascularized, faveolar lungs. In birds, normal lung function requires extensive, dorsally situated nonvascularized abdominal air-sacs ventilated by an expansive sternum and specially hinged costal ribs. The thin walled and voluminous abdominal air-sacs are supported laterally and caudally to prevent inward (paradoxical) collapse during generation of negative (inhalatory) pressure: the synsacrum, posteriorly directed, laterally open pubes and specialized femoral-thigh complex provide requisite support and largely prevent inhalatory collapse. In comparison, theropod dinosaurs probably lacked similarly enlarged abdominal air-sacs, and skeleto-muscular modifications consistent with their ventilation. In the absence of enlarged, functional abdominal air-sacs, theropods were unlikely to have possessed a specialized bird-like, air-sac lung. The likely absence of bird-like pulmonary function in theropods is inconsistent with suggestions of cardiovascular anatomy more sophisticated than that of modern crocodilians. J. Morphol. 2009. © 2009 Wiley-Liss, Inc.