Evolution....I was just wondering....?

I would like to have the opinions of some well educated people on this particular subject.I was just considering the incredible evolutionary journey of the humankind and was left pondering about a few things.I find this human journey even more incredible as I realize how relatively fast we`ve evolved into the very complex living creatures we are today.But my question is,why is that?I mean,the dinosaurs roamed the Earth pretty much undisturbed for about 160 millions years,and apparently,it took only something as major and cataclysmic as an asteroid to bring the reign of these giant reptiles to an abrupt end.By comparison,the earliest hominids fossils found up til now, take us back to only 13-15 millions years ago.On the grand scheme of things,on a cosmic scale,it`s as if we`ve appeared some 5 minutes ago,and already we have acquired such complexity.I just can`t believe that absolutely nothing happened in 160 millions years for some pre-hominids species to develope some sort of intelligence.It`s just strange that in 160 millions years,all what the living creatures did then was to prey,eat,reproduce and die,while in the space of just 15 millions years,hominids has reached a level of intelligence so great that we were lead to call our own brain"the most complex living structure known in the universe"..This is puzzling me and I would like to read your opinions on this matter.Thanks.