( ( Not surprisingly ) ( , ( ( ( the part ) ( of ( ( the brain ) ( that ( controls flight ) ) ) ) ) ( ( is ( the ( ( most developed ) part ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB Not) (RB surprisingly)) (, ,) (NP (NP (DT the) (NN part)) (PP (IN of) (NP (NP (DT the) (NN brain)) (SBAR (WHNP (WDT that)) (S (VP (VBZ controls) (NP (NN flight)))))))) (VP (VBZ is) (NP (DT the) (ADJP (RBS most) (JJ developed)) (NN part))) (. .)))
Not surprisingly, the part of the brain that  controls flight is the most developed part.
(ROOT (S (ADVP (RB Not) (RB surprisingly)) (, ,) (NP (JJ controlling) (NN flight)) (VP (VBZ is) (NP (NP (DT the) (NN function)) (PP (IN of) (NP (NP (DT the) (ADJP (RBS most) (JJ developed)) (NN part)) (PP (IN of) (NP (NP (DT a) (NN bird) (POS 's)) (NN brain))))))) (. .)))