“…Several hypotheses have been proposed to explain the function of these cranial pneumatisation, most of them related to physiology or architecture, development and biomechanics of the skull, such as: imparting resonance to the voice (Cleland, 1862;Bignon, 1889;Leakey & Walker, 1997;Dyce et al, 2002), protection of the brain from shocks (Rui et al, 1960;Schaffer & Reed, 1972;Davis et al, 1996), reducing cranial weight (Cleland, 1862;Paulli, 1900;Nemours, 1931;Shea, 1936;Buhler, 1972;Davis et al, 1996), increasing surface area of olfactory mucosa (Braune & Clasen, 1877;Negus, 1957Negus, , 1958, humidifying and warming the inspired air (Proetz, 1922(Proetz, , 1938O'Malley, 1924;Gannon et al, 1997), thermoregulation of the brain (Bignon, 1889;Bremer, 1940;Proetz, 1953;Verheyen, 1953;Dyce et al, 2002), or producing nitric oxide gas (Lundberg et al, 1994). Nevertheless, no one of these hypotheses is completely satisfactory or widely applicable.…”