( it ( ( 's ( ( those ( three bones ) ) ( in ( the ( middle ear ) ) ) ) ) . ) )
(ROOT (S (NP (PRP it)) (VP (VBZ 's) (NP (NP (DT those) (CD three) (NNS bones)) (PP (IN in) (NP (DT the) (JJ middle) (NN ear))))) (. .)))
it's those three bones in the middle ear.
(ROOT (S (NP (DT The) (JJ mammalian) (JJ middle) (NN ear)) (VP (VBZ has) (NP (CD three) (NNS bones))) (. .)))