( ( Some tetrapods ) ( , ( ( like ( ( whales and ) snakes ) ) ( , ( ( have ( ( lost ( ( some or ) ( all ( of ( the ( four limbs ) ) ) ) ) ) ( ( ( ( that ( ( their ancestors ) had ) ) , ) but ) ( because ( ( of ( their ancestry ) ) ( they ( ( are still ) ( grouped ( as tetrapods ) ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (NP (DT Some) (NNS tetrapods)) (, ,) (PP (IN like) (NP (NNS whales) (CC and) (NNS snakes))) (, ,) (VP (VBP have) (VP (VBN lost) (NP (NP (DT some)) (CC or) (NP (NP (DT all)) (PP (IN of) (NP (DT the) (CD four) (NNS limbs))))) (SBAR (SBAR (IN that) (S (NP (PRP$ their) (NNS ancestors)) (VP (VBD had)))) (, ,) (CC but) (SBAR (IN because) (S (PP (IN of) (NP (PRP$ their) (NN ancestry))) (NP (PRP they)) (VP (VBP are) (ADVP (RB still)) (VP (VBN grouped) (PP (IN as) (NP (NNS tetrapods)))))))))) (. .)))
Some tetrapods, like whales and snakes, have lost some or all of the four limbs that their ancestors had, but because of their ancestry they are still grouped as tetrapods.
(ROOT (S (NP (NNS Caecillians)) (VP (VBD evolved) (PP (IN from) (NP (JJ tetrapod) (NNS ancestors)))) (. .)))