Relationship between brain volume and body mass in primates and marsupials. Data represent 34 species of Haplorrhini, seven species of Strepsirrhini and 19 species of diprotodont marsupials on log–log axes. See Table 1 for equations and statistics for the regression lines.
Relationship between total internal carotid blood flow rate (both arteries) and brain volume for Haplorrhini on log–log axes. Symbols represent the Family Hominidae (great apes), Family Hylobatidae (lesser apes), Superfamily Cercopithecidae (Old World monkeys) and Parvorder Platyrrhini (New World monkeys). Regression line and 95% confidence belts for the regression mean are shown. Selected genera are indicated. See supplementary material Table S1 for the full list of species.
Diagrams of representative skulls of a diprotodont marsupial and a haplorrhine primate, showing the locations of major foramina. The radius of the external opening of the carotid canal is the focus of this study and is easily measured from a ventral view. The carotid canal of the diprotodont enters obliquely and is best viewed from a posterior–ventral–lateral perspective. Note the foramen lacerum of the primate skull, which is plugged with cartilage on the ventral surface, but transmits the carotid artery from the carotid canal into the brain case in life.