| Dal Sasso C., Maganuco S. & Cioffi A., 2009. A neurovascular cavity within the snout of the predatory dinosaur Spinosaurus. First International Congress on North African Vertebrate Palaeontology, 25-27 May 2009 Marrakech (Morocco), 22-23.|
In 2005, Dal Sasso et al. described an almost complete snout of the unusual theropod Spinosaurus, from the Late Cretaceous of Morocco. Siemens CAT scan analysis, performed recently on the same specimen at the Ospedale Maggiore di Milano, reveals that the numerous foramina located on the outer wall of the rostrum communicate with a common internal cavity, deeply encased medially within the premaxillae, which is unique among theropod dinosaurs. The extreme retraction of the external nares in Spinosaurus permits to exclude any respiratory/olfactory function of this cavity, which in turn has a neurovascular nature. The cavity flows into two paired neurovascular passages, going through the entire snout and meeting caudally at level of the fifth maxillary tooth. This suggests that a rostral extension of the trigeminal nerve innervated the cavity.
Soares (2002) demonstrated that the foramina on the facial bones of living and extinct semi-aquatic crocodilians house dome pressure receptors, innervated by the trigeminal nerve, that are useful to hunt even in darkness, detecting prey-made pressure waves associated with disruptions to the air-water interface. According to Taquet (1984) and Holtz (2003), spinosaurids might have hunted in riparian habitats in a manner similar to herons. As for Spinosaurus, we postulate the presence of croc-like pressure receptors, that might have given its mouth, when positioned on the air-water interface, an unexpected tactile function, useful to catch swimming preys without relying on sight.