( ( Cambrian ( ( ( ( The ( earliest period ) ) ( of ( the ( Paleozoic era ) ) ) ) , ) ( ( spanning ( ( the time ) ( between ( ( 544 and ) 505 ) ) ) ) ( ( million years ) ago ) ) ) ) . )
(ROOT (S (VP (VB Cambrian) (NP (NP (DT The) (JJS earliest) (NN period)) (PP (IN of) (NP (DT the) (JJ Paleozoic) (NN era))) (, ,) (VP (VBG spanning) (NP (NP (DT the) (NN time)) (PP (IN between) (NP (CD 544) (CC and) (CD 505)))) (ADVP (NP (CD million) (NNS years)) (RB ago))))) (. .)))
Cambrian The earliest period of the Paleozoic era, spanning the time between 544 and 505 million years ago.
(ROOT (S (NP (NP (DT The) (JJ first) (NN period)) (PP (IN of) (NP (DT the) (JJ paleozoic) (NN era)))) (VP (VBD was) (VP (VBN called) (NP (NN cambrian)))) (. .)))