In researching the Society's usage of the above scriptures, and searching the forum for pre-existing discussions about this, I realized that there was a good one just a few days ago here: http://www.jehovahs-witness.net/watchtower/beliefs/268309/1/The-argument-JW60s-use-for-animal-predators-on-land-what-argument-do-they-have-for-marine-predators
But I think the only direct answer to the OP's question is that (1) the Society talks about dinosaurs as little as possible, besides the article I mentioned above from 1990, and (2) if dinosaurs ate each other it would only be as scavengers, to serve as a cleanup crew, rather than preying on their live fellow saurians.