Cranial endocast of the carcharodontosaurid theropod Giganotosaurus carolinii Coria and Salgado

PAULINA CARABAJAL, ARIANA; CANALE, JUAN IGNACIO

Trelew, Provincia de Chubut, Argentina

Jornada; XXIII Jornadas Argentinas de Paleontología de Vertebrados; 2007

A complete latex endocast was made after removing the sediment filling the cerebral cavity of the braincase of Giganotosaurus, thereby allowing the description of the endocranial anatomy of the specimen. The endocast is compared with the few other known natural or artifical theropod endocasts. As in Carcharodontosaurus Stromer, the olfactory bulbs are aligned with the forebrain, the midbrain is posteroventrally inclined  and the hindbrain is parallel but ventral to the forebrain, showing similarly angled cephalic and pontine flexures. The olfactory bulbs are well developed and are separated by a bony septum. The olfactory tract is robust, long and shallowly upward convex, and is vascularized by two pairs of unrecognized blood vessels. The floccular process of the cerebellum is large and is dorsal to nerve V. The cranial nerves and blood vessels have a similar disposition as in Carcharodontosaurus with the difference that in Giganotosaurus there is only one branch for cranial nerve XII and cranial nerve XI has a separate internal opening from the vagus foramen (metotic foramen). In Carcharodontosaurus is separate openings as well, but it is anterior in position and was probably utilized by cranial nerve IX. The length of the endocast, including the olfactory bulbs, is approximately 19% longer tan the endocast in Carcharodontosaurus.