Screaming or howling in Greene County, Missouri

The events of that I am about to relate to you happened on August 9, 2002. just outside of Springfield Missouri. It was about 2:00am. My son and I had driven out into the country to get away from the city lights to watch the Persudes meteor Shower. We drove south on Hwy ZZ and stopped at the top of a large hill. We turned west onto a gravel road and stopped on the top of a hill. There were no close by trees or structures to interfere with our viewing of the night sky. It was a clear night with no moon. After a few minutes in the dark our eyes adjusted quite well. We could see the open fields to the East and south and north of us. Looking west we could see the light colored road going down the hill and off into the distance. After watching the sky for a few minutes I noticed out of the corner of my eye something large moving in the field south of us. At first I couldn't tell if I was actually seeing something or not, when I looked directly at it I couldn't see it but then if I looked off center of it I could see it in my peripheral vision. At times it seemed to be moving west then east. I realized it was zigzagging back and forth. I asked my son if he saw it but he didn't. About then there was a flurry of shooting stars and I diverted attention to the sky again figuring it must have been a cow or a deer. After a few minutes both my son and I were facing north east when we heard a very deep and loud growl from behind us. Almost together we turned to each other and said" did you hear that". Turning around we both could see a large object in the road. We could not make out any details except its outline against the light colored roadway. It was huge, it seemed to have a roughly man like shape but a kind of cone head and extremely wide shoulders. It was swaying back and forth about half way down the hill. After watching it for a few seconds I realized that it was swaying back and forth because it was walking up the hill toward us. At this time it growled yet again, a very low deep rumble like growl. I noticed how quiet everything else was. In fact I remember thinking how funny it was that the thing made no sound on the gravel as it walked. By this time it was getting fairly close, perhaps three to four car lengths away. It growled once again very loud and what seemed unnaturally long. With that my son screamed "lets get the hell out of here" We jumped into our car and I floored it down the road and back to the highway. I didn't slow down till we hit town. The next day, (in full daylight of course) I went back out to the spot. I didn't find any tracks or anything. I did however notice that there was a 4 foot high barbwire fence between the field on the South and the road. If this thing was the same thing that I had seen in the field zigzagging across it would have had to step or jump the fence, as the fence was not strong enough for anyone to climb. Especially something as big as this. I do not know what it was but it obviously did not want us there and made no bones about it. I am very curious if anyone else in this area has seen anything similar recently.