Neurovascular system and dental renewal in the rostrum of Spinosauridae: new descriptions and implications on non-olfactive snout sensitivity of dinosaurs

The morphological analogy between the Spinosauridae and crocodilians rostrum has been widely documented. More recently, the supposed existence in Spinosauridae of specialized sensory organs such as those encountered in crocodilians (called ISOs for Integumentary Sensorial Organs) has been advanced by some authors. However, no complete representation of the neurovascular network in Spinosauridae rosette had yet been described and the association between dense neurovascular branching and skin sensitivity remained only a hypothesis. The amazing internal preservation of the premaxillae of Cristatusaurus lapparenti Taquet & Russell, 1998 and Spinosaurus maroccanus Russell, 1996 from the MNHN of Paris finally gives us now a precise idea of the situation. We show by our tomographic results one of the best-preserved neurovascular complex discovered in a dinosaur and the very first complete in a Spinosauridae with the mature specimen of Cristatusaurus lapparenti. We found that the volume of the neurovascular system, the size of the foramina that coincides admirably with that of the underlying branches, and the complexity of the observed ramifications represent additional evidence supporting the hypothesis of a hypersensitivity of the rosette of these animals. Comparisons with other extinct and modern creatures that have developed efficient sensory structures on the front of their snouts were also made. In addition, our results tend to show a particularly high rate of tooth replacement in Spinosauridae from a very young age.