Nasal aperture area and body mass in felids: Ecophysiological implications and paleobiological inferences

In order to study the adaptive significance of the nasal chamber in felids (Mammalia, Carnivora), we measured the nasal aperture area and used it as an indirect estimate of the nasal chamber volume. We assume that this measurement relates to the metabolic demands for oxygen by animals, which in turn would depend on their mass, hunting techniques and/or the environment inhabited. The proven relationship between nasal aperture area and body size among living felids was used to estimate the mass and different aspects of the paleobiology of nine extinct felids from the New and Old World, six of the subfamily Machairodontinae and three of the subfamily Felinae. Results obtained confirm that the North American lion and the Eurasian cave lion were both comparable in size, with a body about 25% heavier than in today's lions. The large nasal apertures of smilodontines suggest that, compared to extant felids with skulls of similar length, these ambushing saber-tooth cats had a more robust body and thus greater oxygen demands. In contrast, coursing homotherines had longer skulls, narrower palates and a more lightened body than other saber-tooth cats.