The term supramarginal gyrus refers to the more rostral of two subdivisions of the inferior parietal lobule identified by dissection in the human ( Carpenter-1983 ) and the macaque ( Martin-2000 ). In the human it is separated rostrally from the postcentral gyrus by the postcentral sulcus. Dorsally its border with the superior parietal lobule is marked by the intraparietal sulcus. Ventrally it surrounds the termination of the lateral fissure, which provides its boundary with the superior temporal gyrus rostral to the fissure. Its ventrocaudal border with the superior temporal gyrus is an ill-defined line that connects the terminal descending limb of the lateral fissure horizontally to the rostral boundary of the occipital lobe ( Duvernoy-1992 ). The boundaries in the macaque are the same except that the rostral border with the postcentral gyrus, a vertical line from the rostral tip of the intraparietal sulcus to the lateral fissure, is unmarked by anatomical feature. And it does not surround the termination of the lateral fissure, so its caudal boundary with the angular gyrus is marked by the superior temporal sulcus and the parieto-occipital sulcus ( Martin-2000 ). Equivalent structures are not found in the smooth cerebral cortex of the rat or mouse ( NeuroNames ).