( ( The ( first cell ) ) ( ( ( appeared over ) ( ( ( 4 billion ) years ) ago ) ) . ) )
(ROOT (S (NP (DT The) (JJ first) (NN cell)) (VP (VBD appeared) (PRT (RP over)) (ADVP (NP (QP (CD 4) (CD billion)) (NNS years)) (RB ago))) (. .)))
The first cell appeared over 4 billion years ago.
(ROOT (S (NP (DT The) (JJ first) (VBG living) (NNS cells)) (VP (MD may) (VP (VB have) (VP (VBN evolved) (ADVP (NP (QP (RB around) (CD 4) (CD billion)) (NNS years)) (RB ago))))) (. .)))