( ( ( ( The ( ( famous crocodile ) smile ) ) , ) ( where ( they ( hold ( ( their mouths ) ( wide open ) ) ) ) ) ) ( ( is ( ( a ( cooling mechanism ) ) ( that ( exposes ( the ( ( highly vascularized ) throat ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (ADJP (JJ famous) (JJ crocodile)) (NN smile)) (, ,) (SBAR (WHADVP (WRB where)) (S (NP (PRP they)) (VP (VBP hold) (S (NP (PRP$ their) (NNS mouths)) (ADJP (RB wide) (JJ open))))))) (VP (VBZ is) (NP (NP (DT a) (VBG cooling) (NN mechanism)) (SBAR (WHNP (WDT that)) (S (VP (VBZ exposes) (NP (DT the) (ADJP (RB highly) (JJ vascularized)) (NN throat))))))) (. .)))
The famous crocodile smile, where they hold their mouths wide open is a cooling mechanism that exposes the highly vascularized throat.
(ROOT (S (S (VP (VBG Lying) (PP (IN with) (NP (PRP$ their) (NNS mouths))) (ADVP (RB open)))) (, ,) (NP (DT a) (NN behavior)) (VP (VBD called) (SBAR (S (NP (NNP gaping)) (, ,) (ADVP (RB probably)) (VP (VBZ serves) (NP (NP (DT the) (NN function)) (PP (IN of) (S (VP (VBG cooling) (PRT (RP down)) (PP (IN for) (NP (NNS crocodiles))))))))))) (. .)))