a pack of dogs who are smarter than him 
(ROOT (NP (NP (NP (DT a) (NN pack)) (PP (IN of) (NP (NNS dogs)))) (SBAR (WHNP (WP who)) (S (VP (VBP are) (ADJP (ADJP (JJR smarter)) (PP (IN than) (NP (PRP him)))))))))
(ROOT (NP (NP (NP (DT ) (NN )) (PP (IN ) (NP (NNS )))) (SBAR (WHNP (WP )) (S (VP (VBP ) (ADJP (ADJP (JJR )) (PP (IN ) (NP (PRP )))))))))