( ( ( Carbon 14 ) dating ) ( ( is ( ( based ( on ( ( the measurement ) ( of ( ( the amount ) ( of ( ( a ( radioactive isotope ) ) ( of carbon ) ) ) ) ) ) ) ) ( in ( ( an object ) ( that ( once ( was living ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Carbon) (CD 14)) (VP (VBG dating))) (VP (VBZ is) (VP (VBN based) (PP (IN on) (NP (NP (DT the) (NN measurement)) (PP (IN of) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (DT a) (JJ radioactive) (NN isotope)) (PP (IN of) (NP (NN carbon))))))))) (PP (IN in) (NP (NP (DT an) (NN object)) (SBAR (WHNP (WDT that)) (S (ADVP (RB once)) (VP (VBD was) (VP (VBG living))))))))) (. .)))
Carbon 14 dating is based on the measurement of the amount of a radioactive isotope of carbon in an object that once was living.
(ROOT (S (NP (NP (NNP Carbon) (CD 14) (NN isotope)) (PP (IN of) (NP (NN carbon)))) (VP (VBZ is) (ADVP (RB typically)) (VP (VBN used) (PP (TO to) (NP (NN date) (JJ ancient) (NNS items))))) (. .)))