In mammals, the cortical part of the pallium registers a definite evolutionary step-up in complexity, forming the cerebral cortex, most of which consists of a progressively expanded six-layered portion isocortex, with simpler three-layered cortical regions allocortex at the margins.
12.
A small area where the frontal lobe meets the temporal lobe and the area of cortex on the uncus of the parahippocampal gyrus ( both belonging to the olfactory cortex ) have a different structure ( so called " allocortex " ) than most of the telencephalon and are phylogenetically older ( so called paleocortex ).
13.
It used to be thought that pallium equals cortex and subpallium equals telencephalic nuclei, but it has turned out, according to comparative evidence provided by molecular markers, that the pallium develops both cortical structures ( allocortex and isocortex ) and pallial nuclei ( claustroamygdaloid complex ), whereas the subpallium develops striatal, pallidal, diagonal-innominate and preoptic nuclei, plus the corticoid structure of the olfactory tuberculum.
