radiocarbon dating: a chemical analysis used to determine the age of organic materials based on their content of the radioisotope carbon-14; believed to be reliable up to 40,000 years
dating: use of chemical analysis to estimate the age of geological specimens
interventricular foramen: the small opening (on both the right and left sides) that connects the third ventricle in the diencephalon with the lateral ventricle in the cerebral hemisphere