( ( Unlike tunicates ) ( , ( lancelets ( ( retain ( ( all ( four ( defining ( chordate traits ) ) ) ) ( in ( the ( adult stage ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Unlike) (NP (NNS tunicates))) (, ,) (NP (NNS lancelets)) (VP (VBP retain) (NP (NP (DT all) (CD four) (JJ defining) (NN chordate) (NNS traits)) (PP (IN in) (NP (DT the) (JJ adult) (NN stage))))) (. .)))
Unlike tunicates, lancelets retain all four defining chordate  traits in the adult stage.
(ROOT (S (NP (JJ Adult) (NNS humans)) (VP (VBP lack) (NP (NP (DT some)) (PP (IN of) (NP (NP (DT the) (VBG defining) (NNS traits)) (PP (IN of) (NP (NNS chordates))))))) (. .)))