WHEN: Late 60's - Early 70's

OBSERVED: This scenerio has been in my mind for a long time. Over 30 years ago, myself and some friends drove down a road that was pretty much farm roads. We stopped in a pasture and just sat around and talked. It was well after dark. We heard some noise coming frombehind the car and turned around and saw a large creature coming towards us, approaching the back of the car. We were all scared out of our minds and started the car and proceeded to leave. Needless to say, we ran into some tree stumps that the farmer had cut down and had a heck of a time getting out of there. My sister wet her pants she was so scared. We kept looking back and it was still chasing us. It wasn't until we gained road that we lost it. It was close enough to the back window that there were smudge marks on it. This was a field and or pasture which contained cows, but I seriously think a cow would not have done this kind of chase. This "Thing" came out from behind some trees that were edging the pasture and just came charging at us. This was in the summer so we had the windows down and the only way we heard the approach was the sound of a "thunp, thump" noise coming from the back of the car. All I can say is that whatever it was, it was much larger than the car and on two feet. Thanks, I have always wondered what it was.