( ( ( ( ( ( ( Crocodilians ' ) hearts ) ( have ( ( four chambers ) ( like ( ( mammals and ) birds ) ) ) ) ) , ) but ) ( there ( is ( ( a pore ) ( between ( ( the ( ( ( left and ) right ) ventricles ) ) ( which ( allows ( some mixing ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NP (NNP Crocodilians) (POS ')) (NNS hearts)) (VP (VBP have) (NP (NP (CD four) (NNS chambers)) (PP (IN like) (NP (NNS mammals) (CC and) (NNS birds)))))) (, ,) (CC but) (S (NP (EX there)) (VP (VBZ is) (NP (NP (DT a) (NN pore)) (PP (IN between) (NP (NP (DT the) (ADJP (NN left) (CC and) (JJ right)) (NNS ventricles)) (SBAR (WHNP (WDT which)) (S (VP (VBZ allows) (NP (DT some) (NN mixing)))))))))) (. .)))
Crocodilians' hearts have four chambers like mammals and birds, but there is a pore between the left and right ventricles which allows some mixing.
(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))))) (. .)))