( ( ( The ancestors ) ( of ( these organisms ) ) ) ( ( were ( ( the ( ( most primitive ) members ) ) ( of ( the clade ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NNS ancestors)) (PP (IN of) (NP (DT these) (NNS organisms)))) (VP (VBD were) (NP (NP (DT the) (ADJP (RBS most) (JJ primitive)) (NNS members)) (PP (IN of) (NP (DT the) (NN clade))))) (. .)))
The ancestors of these organisms were the most primitive members of the clade.
(ROOT (S (NP (DT A) (NN clade)) (VP (VBZ is) (NP (NP (CD one) (NN way)) (PP (IN of) (NP (VBG classifying) (NNS organisms))))) (. .)))