Although dinosaurs were not so stupid as is usually supposed, they did not evolve to a civilization. Why other species evolved (we), that is precisely the question that antropology tries to solve. Of course thee are phyical factors, since a tiny organism will probably survive better bad times than a tank of fourty tons. But why did insects, which are, with no doubt, the organisms best adapted to almost any kind of adverse atmospherical conditions, not evolve to the leading group?
P.S: the crime statistics' in any big city show that human beings stopped to evolve many centuries ago.