( ( As ( in mammals ) ) ( , ( birds ( ( have ( a ( four-chambered heart ) ) ) ; ) ) ) )
(ROOT (S (PP (IN As) (PP (IN in) (NP (NNS mammals)))) (, ,) (NP (NNS birds)) (VP (VBP have) (NP (DT a) (JJ four-chambered) (NN heart))) (: ;)))
As in mammals, birds have a four-chambered heart;
(ROOT (S (PP (IN Like) (NP (NP (DT all) (NNS tetrapods)) (PP (IN except) (NP (NNS birds) (CC and) (NNS mammals))))) (, ,) (NP (NNS frogs)) (VP (VBP possess) (NP (NP (DT a) (NN heart)) (PP (IN with) (NP (CD three) (NNS chambers))))) (. .)))