The supraorbital bone above the eye that contacted between the lacrimal and postorbital bones was eave-like, and similar to that of "Abelisaurus". The quadrate bone at the back of the skull was long, and had two pneumatic (air-filled) foramina (holes) on the inner side. The skull roof (formed by the frontal and parietal bones) was broad and formed a "shelf", which overhung the short supratemporal fenestrae at the top rear of the skull. The jaw articulated far behind the occipital condyle (where the neck is attached to the skull) compared to other theropods. The condyle was broad and low, and had pneumatic cavities. "Giganotosaurus" did not have a sagittal crest on the top of the skull, and the jaw muscles did not extend onto the skull roof, unlike in most other theropods (due to the shelf over the supratemporal fenestrae). These muscles would instead have been attached to the lower side surfaces of the shelf. The neck muscles that elevated the head would have attached to the prominent supraoccipital bones on the top of the skull, which functioned like the nuchal crest of tyrannosaurs. A latex endocast of the brain cavity of "Giganotosaurus" showed that the brain was similar to that of the related genus "Carcharodontosaurus", but larger. The endocast was long, wide, and had a volume of . The dentary of the lower jaw expanded in height towards the front (by the mandibular symphysis, where the two halves of the lower jaw connected), where it was also flattened, and it had a downwards projection at the tip (which has been referred to as a "chin"). The lower side of the dentary was concave, the outer side was convex in upper view, and a groove ran along it, which supported foramina that nourished the teeth. The inner side of the dentary had a row of interdental plates, where each tooth had a foramen. The Meckelian groove ran along the lower border. The curvature of the dentary shows that the mouth of "Giganotosaurus" would have been wide. It is possible that each dentary had twelve alveoli (tooth sockets). Most of the alveoli were about 3.5 cm (1.3 in) long from front to back.