Olfactory acuity in early sauropodomorph dinosaurs

Abstract

ABSTRACT The study of sensorial systems of extinct animals provides clues on their biology and behaviour. Olfaction is an important sensory modality, which is used in a range of tasks, such as foraging, reproduction, predator avoidance and social interaction. The olfactory acuity of dinosaurs has been investigated through quantitative approaches. However, these studies focused on the Theropoda lineage. Regarding sauropodomorphs, there are no studies focused on their olfactory capabilities. Furthermore, cranial endocasts with preserved olfactory portions are scarce for the earliest sauropodomorphs. Hence, the olfaction in the sauropodomorphs is obscure. Here, the olfactory ratio (ratio between the size of the olfactory bulbs and cerebral hemispheres) of some sauropodomorphs is calculated and plotted as a function of body mass in a sample of dinosaurs. The results reveal that the olfactory ratio increases with increasing body mass in sauropodomorphs. Moreover, the olfactory ratio of early sauropodomorphs is significantly higher than those predicted for dinosaurs of similar body mass, regardless of diet. In sauropods, the ratio ranges from low to high, revealing distinct olfactory capabilities. According to the present results, the olfactory system played an important role in the whole evolutionary history of sauropodomorphs.