Katz, E.P.*; Hillman, S.S.: Cross-Sectional Area of the Nasal Passages of the Odontoceti. Implications for Paleophysiology

In search of evidence bearing on the endothermic dinosaur hypothesis, a recent study by Ruben et al. (1996) revealed that endotherms tend to have larger nasal cross-sectional areas than ectotherms of the same mass. The reason offered for this observation was that larger nasal passages are needed to house the complex respiratory turbinates posessed by endotherms. Whales were excluded from the study on the grounds that they have no nasal turbinates. In the present study, the cross-sectional areas of the nasal passages of nine species of Odontoceti were measured using latex casts. The regression of log cross-sectional area vs. log mass for the whales was the same as for the endotherms of the previous study. Alternative explainations for the large nasal cross-sectional area of endotherms are sought.