( It ( ( is ( assumed ( to ( be ( either ( ( ( a herbivore ) or ) ( an omnivore ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (VP (VBN assumed) (S (VP (TO to) (VP (VB be) (NP (CC either) (NP (DT a) (NN herbivore)) (CC or) (NP (DT an) (NN omnivore)))))))) (. .)))
It is assumed to be either a herbivore or an omnivore.
(ROOT (S (NP (NNS Mammals)) (VP (MD may) (RB either) (VP (VB be) (NP (NNS herbivores) (, ,) (NNS omnivores) (CC or) (NNS herbivores)))) (. .)))