( ( Amniotic eggs ) ( ( have ( ( a shell ) ( that ( retains water ) ) ) ) . ) )
(ROOT (S (NP (JJ Amniotic) (NNS eggs)) (VP (VBP have) (NP (NP (DT a) (NN shell)) (SBAR (WHNP (WDT that)) (S (VP (VBZ retains) (NP (NN water))))))) (. .)))
Amniotic eggs have a shell that retains water.
(ROOT (S (NP (NNS Mammals)) (VP (VP (VBP have) (NP (CD four) (NNS limbs))) (CC and) (VP (VBP produce) (NP (JJ amniotic) (NNS eggs)))) (. .)))