"Radioisotope dating is done on the rocks that fossils are found in ."
"Actually , the dating is done on layers above and below the rock in which fossils are found . You see , generally fossils are found in some sort of sedimentary rock . And sedimentary rock can not be dated . But a layer of volcanic ash above and below the fossil can be dated and thus give a date within a range ."
"Radioisotope dating is done on the rocks that fossils are found in ."
"the dating is done on layers above and below the rock in which fossils are found ."