Résumé
Sinuses are internal skull cavities of elusive function, which are often neglected and considered as rare in rodents. Given the great morphological and ecological diversity of ctenohystrican rodents, they represent a promising model to investigate sinuses cavities. Thus, we employed X-Ray μComputed Tomography and 3D segmentation protocols to visualize, reconstruct, and describe sinus presence and shape in 42 genera of Ctenohystrica rodents. Within them, 19 genera exhibitsdeveloped frontal sinuses, conspicuously in genera of chinchilids, capromids, dactylomines, dinomyids, South American and African porcupines, and the giant extinct species Elasmodontomys obliquus. Sinuses are majorly distributed in frontal bones, although in some genera extend to nasals and parietal bones, e.g. Coendou and Histrix. The other 23 genera did not present sinuses, however can display extensively developed spongeous bone in some cases (e.g. Dasyprocta and Cuniculus). Sinuses and turbinals are often connected via recesses, which challenges the recognition of the former as independent skull cavities. This study provides novel insights into sinus morphology and evolution in Ctenohystrica, which are more commonly found than previously reported. We show that their presence, shape, and size vary greatly between genera, with large to medium size ctenohystrican rodents often showing more developed sinuses. Although their adaptive nature remains uncertain, we demonstrate their contribution to high-level systematics of mammals as potential novel informative diagnostic traits, for which proper quantitative analyses are now necessary.