Report 50155: Memory of seeing something chimp-like in the trees and being chased out of the woods near Brereton

Was at a creek where I hung out almost every summer with my brothers and friends. Was probably sometime in July,1969. there was a huge tree about 300 ft. from a bridge that went across the creek. Myself and 2 younger brothers were on this bridge on our bikes. I saw something big in that tree 300 ft. away. I kept an eye on it, then I saw something same size as a full grown chimp. About 4 ft. tall, swinging from limb to limb and just playing in the tree. I told my brothers, look at that huge monkey!. We sat and watched it for 5 incredulous minutes. I could't believe my eyes. All of a sudden, I had this incredible over whelming sense of terror. Didn't see anything threatening; just felt terrified. I told my brothers we have to go and right now! I made them follow me and on the way up, my middle brother said go fast! There is a man chasing me. he was in the rear of us. We rode as fast as we could about a half mile home and he said it was a strange hairy man chasing us. I think it was a bigfoot protecting its young in the tree. It just chases us off. I didn't go back to that creek the rest of the summer. Scared me to death.