If the environment is filled with a mix of giant animals and smaller animals, and there is a food shortage, the smaller ones, who need less fuel to keep them going, are going to have a better chance of winning out. Your idea that animals should just get more and more dangerous while they grow bigger and bigger is, well, ridiculous. You do see that. In fact, every animal around could be considered a transitional species. But since we can't predict the future, we just don't know what they might be transitioning into.
Evolution works continually.
It's happening all around you whether you realize it or not. All I can do is urge you to pick up a basic biology textbook before making claims about this topic again. The best scientific minds in the world have discussed and debated evolution, according to scientific principles, for over 100 years. Cecil's Mailbag is researched and written by members of the Straight Dope Science Advisory Board, Cecil's online auxiliary. Inc. All rights reserved.