Implications of an avian‐style respiratory system for gigantism in sauropod dinosaurs

• DOI: 10.1002/jez.517
• Publication Date: 2009-02-02T19:07:37Z
• Authors: Steven F. Perry; Andreas Christian; Thomas Breuer; Nadine Pajor; Jonathan R. Codd
• Keywords: 0106 biological sciences; Respiratory System; Animals; 01 natural sciences; Body Temperature; Dinosaurs

AbstractIn light of evidence for avian‐like lungs in saurischian dinosaurs, the physiological implications of cross‐current gas exchange and voluminous, highly heterogeneous lungs for sauropod gigantism are critically examined. At 12 ton the predicted body temperature and metabolic rate of a growing sauropod would be similar to that of a bird scaled to the same body weight, but would increase exponentially as body mass increases. Although avian‐like lung structure would be consistent with either a tachymetabolic‐endothermic or a bradymetabolic‐gigantothermic model, increasing body temperature requires adjustments to avoid overheating. We suggest that a unique sauropod structure/function unit facilitated the evolution of gigantism. This unit consisted of (1) a reduction in metabolic rate below that predicted by the body temperature, akin to thermal adaptation as seen in extant squamates, (2) presence of air‐filled diverticula in the long neck and in the visceral cavity, and (3) low activity of respiratory muscles coupled with the high efficiency of cross‐current gas exchange. J. Exp. Zool. 311A:600–610, 2009. © 2009 Wiley‐Liss, Inc.