( ( Eukaryotic cells ) ( first ( ( appeared ( ( ( about ( 1.5 billion ) ) years ) ago ) ) . ) ) )
(ROOT (S (NP (JJ Eukaryotic) (NNS cells)) (ADVP (RB first)) (VP (VBD appeared) (ADVP (NP (QP (RB about) (CD 1.5) (CD billion)) (NNS years)) (RB ago))) (. .)))
Eukaryotic cells first appeared about 1.5 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))))) (. .)))