The remains of what may be the largest Dinosaur ever discovered have been found in Argentina:
http://www.nbcnews.com/news/world/dinos ... ed-n107966
I heard a little about this on the TV news this afternoon and it sounds like this thing was really huge, and it lived many, many, many years ago.
Although in a way they sound kind of scary, I think Dinosaur's are also kind of cool. I certainly would not want to meet up with one though.