(S (S (BASENP (DT This)) (VP (VBZ is) (NP (BASENP (DT the) (JJ first) (NN study)) (SBAR (WHNP (WDT that)) (S (VP (VBZ indicates) (NP (BASENP (JJ magnetic) (NN field) (NN detection)) (PP (IN in) (BASENP (JJ large) (NNS mammals)))))))))) (PERIOD .))