( ( ( ( ( Birds ( evolved ( from reptiles ) ) ) , ) and ) ( ( ( a ( connecting link ) ) ( to ( their ( reptilian ancestors ) ) ) ) ( ( can sometimes ) ( be ( seen ( in ( their ( scaly legs ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNP Birds)) (VP (VBD evolved) (PP (IN from) (NP (NNS reptiles))))) (, ,) (CC and) (S (NP (NP (DT a) (JJ connecting) (NN link)) (PP (TO to) (NP (PRP$ their) (NN reptilian) (NNS ancestors)))) (VP (MD can) (ADVP (RB sometimes)) (VP (VB be) (VP (VBN seen) (PP (IN in) (NP (PRP$ their) (JJ scaly) (NNS legs))))))) (. .)))
Birds evolved from reptiles, and a connecting link to their reptilian ancestors can sometimes be seen in their scaly legs.
(ROOT (S (NP (NNP Birds)) (VP (VBD evolved) (PP (IN from) (NP (JJ reptile) (NNS ancestors)))) (. .)))