[dinosaur] Was T. rex a lion or rather a crocodile?

Good day to all listmembers, I was wondering if the concept of agile, dynamic T. rex, running across the landscape (e. g. on wonderful Mr. Paul's illustrations) is correct according to recent discoveries and research? In other words, was it really (in the ecological sense) similar to modern lions or rather to a crocodiles (i. e. relatively slow ambush predator dwelling in more swampy areas)? Thank you for your thoughts!