( They ( ( ( ( hunted ( woolly ( ( rhino and ) cave-bear ) ) ) and ) ( disappeared ( ( ( about 30,000 ) years ) ago ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VP (VBZ hunted) (NP (JJ woolly) (NN rhino) (CC and) (NN cave-bear))) (CC and) (VP (VBD disappeared) (ADVP (NP (QP (RB about) (CD 30,000)) (NNS years)) (RB ago)))) (. .)))
They hunted woolly rhino and cave-bear and disappeared about 30,000 years ago.
(ROOT (S (NP (JJ Woolly) (NNS mammoths)) (VP (VBD began) (S (VP (TO to) (VP (VB go) (NP (NP (ADJP (JJ extinct)) (NNS thousands)) (PP (IN of) (NP (NNS years)))) (ADVP (RB ago) (PP (IN because) (PP (IN of) (S (VP (VBG hunting) (PP (IN by) (NP (NNS humans)))))))))))) (. .)))
Woolly mammoths began to go extinct thousands of years ago because of hunting by humans.