( Mammals ( , ( ( like birds ) ( , ( ( possess ( a ( four-chambered heart ) ) ) . ) ) ) ) )
(ROOT (S (NP (NNS Mammals)) (, ,) (PP (IN like) (NP (NNS birds))) (, ,) (VP (VBP possess) (NP (DT a) (JJ four-chambered) (NN heart))) (. .)))
Mammals, like birds, possess 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))))) (. .)))