( ( During ( the ( early Paleozoic ) ) ) ( , ( ( ( the amount ) ( of ( ( carbon dioxide ) ( in ( the atmosphere ) ) ) ) ) ( ( was ( ( much greater ) ( than ( it ( is today ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN During) (NP (DT the) (JJ early) (NN Paleozoic))) (, ,) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN carbon) (NN dioxide)) (PP (IN in) (NP (DT the) (NN atmosphere)))))) (VP (VBD was) (ADJP (ADJP (RB much) (JJR greater)) (SBAR (IN than) (S (NP (PRP it)) (VP (VBZ is) (NP (NN today))))))) (. .)))
During the early Paleozoic, the amount of carbon dioxide in the atmosphere was much greater than it is today.
(ROOT (S (PP (IN During) (NP (DT the) (JJ early) (NN paleozoic))) (, ,) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN carbon) (NN dioxide)) (PP (IN in) (NP (DT the) (NN atmosphere)))))) (VP (VBD was) (ADJP (RB much) (JJR greater)) (PP (VBN compared) (PP (TO to) (NP (NN today))))) (. .)))