( ( In birds ) ( , ( oogenesis ( ( is ( lacking ( one ( of ( these events ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NNS birds))) (, ,) (NP (NNS oogenesis)) (VP (VBZ is) (VP (VBG lacking) (NP (NP (CD one)) (PP (IN of) (NP (DT these) (NNS events)))))) (. .)))
In birds, oogenesis is lacking one of these events.
(ROOT (S (NP (CD One) (JJ large) (NNS eggs)) (VP (VBP are) (VP (VBN generated) (PP (IN during) (NP (NNS oogenesis))))) (. .)))