( ( For example ) ( , ( ( ( the wings ) ( of ( ( ( ( ( birds , ) ( human arms ) ) , ) and ) ( ( pectoral fin ) ( in fish ) ) ) ) ) ( ( ( are all ) ( derived ( from ( ( a ( common ancestor ) ) ( ( In contrast ) ( , ( ( features ( that ( are ( similar ( because ( they ( have ( ( evolved ( in response ) ) ( to ( a ( common ( environmental pressure ) ) ) ) ) ) ) ) ) ) ) ) ( are ( said ( to ( be analogous ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NN example))) (, ,) (NP (NP (DT the) (NNS wings)) (PP (IN of) (NP (NP (NNS birds)) (, ,) (NP (JJ human) (NNS arms)) (, ,) (CC and) (NP (NP (JJ pectoral) (NN fin)) (PP (IN in) (NP (NN fish))))))) (VP (VBP are) (RB all) (VP (VBN derived) (PP (IN from) (NP (NP (DT a) (JJ common) (NN ancestor)) (SBAR (S (PP (IN In) (NP (NN contrast))) (, ,) (NP (NP (NNS features)) (SBAR (WHNP (WDT that)) (S (VP (VBP are) (ADJP (JJ similar) (SBAR (IN because) (S (NP (PRP they)) (VP (VBP have) (VP (VBN evolved) (PP (IN in) (NP (NN response))) (PP (TO to) (NP (DT a) (JJ common) (JJ environmental) (NN pressure)))))))))))) (VP (VBP are) (VP (VBN said) (S (VP (TO to) (VP (VB be) (ADJP (JJ analogous))))))))))))) (. .)))
For example, the wings of birds, human arms, and pectoral fin in fish are all derived from a common ancestor In contrast, features that are similar because they have evolved in response to a common environmental pressure are said to be analogous.
(ROOT (S (NP (NP (DT The) (NN bird) (NN ancestor)) (SBAR (WHNP (WDT that)) (S (VP (VBD lived) (PP (IN in) (NP (NNS trees))))))) (VP (VBD developed) (NP (NP (NNS wings)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADVP (RB commonly)) (VP (VBN associated) (PP (IN with) (NP (NNS birds))))))))) (. .)))
The bird ancestor that lived in trees developed wings, which is commonly associated with birds.