Screaming or howling in Parker County, Texas

My girlfriend and I were parking at the edge of a creek flowing into the back of the lake. It was dark and under the cover of trees where we were parked you could not see your hand in front of your face. We had the windows cracked little and were in the back seat of the car when we heard something out of the ordinary. We had been there before so knew the usual night sounds in the area. A owl lived in the big tree near by and hooted all the time. The hill in front of the car went down to a swamp with a creek in the middle going to the lake. There was crickets, frogs and locust all making there normal sounds that night. But we heard something coming through the leaves in the bottoms, it sounded like it was heading to our car. I have spent a lot of time in the woods hunting, fishing and trapping growing up so I don't get spooked to easy. At first I thought it was a cow, but then we noticed all the night sounds were gone, no frogs, crickets, owl - dead quiet except the foot steps. They were on 2 feet a step and a drag step like it had a hurt foot or something. Then being a kid I thought of all the horror movies I watched and figured it was a guy who jumped the train and was coming to kill us and take our car. As the steps got closer I got really bugged, it was coming up the hill right at the car. Finally after what I thought was an eternity I flew over the front seat and started the car, the only problem was it was a new car she just bought and I never drove it. She was screaming about dieing or something when I threw it in reverse and stomped the gas. I was there before and new the road opened up behind me so as I was going backwards I hit the light switch. This was a big mistake because it turned out to be the cigarette lighter, as soon as we came out of the tree cover we got some moonlight and I found the headlight switch. This all happened really quick, but I looked up and there was this animal leaping over the hill going into the creek, it was really wide at the shoulders and had almost no neck. I thought at first it was a bear but there was not any bears in this area. I saw a big brownish black creature running through the trees. I saw two shoulders and the back of the head go between two trees, later measured to be about 4.5 feet apart. It covered between them easily. I asked my girlfriend did you see that, she said she saw a brown spot in the lights like a bear on two legs. I think the car scared it, so we went to town for help. After we got more people, truck's with lights and some equipment we came back. We left the truck lights shining in the bottoms and looked around for tracks with our flashlights. We started to look for footprints, the ground was dry and covered with leaves but we did find large scrapes going up the hill to where the car was parked, they looked like it was where the animal jumped over the hill. They were very far apart, I had to stretch as far as I could from the one on the bottom to the one at the top. I am 6' 4" with a 38" inseam, this was a large stride. This is when the whole woods went quiet again, it was nuts, 5 pretty big guys all standing in a circle like a herd of buffalo back to back, scared I guess, none of us moved a muscle. Flashlights and guns pointed out at the dark we listened to the dead quiet of the woods. Then all of a sudden a tree limb snaps - loud, and then everything gets back to normal. Then one by one the frogs, crickets, owls all started making noise again. Really strange night for sure. The next day my brother and a friend went to walk the creek with buckshot in our shotguns. We walked about a half mile down the creek spread out like small game hunting. We came to the area where the railroad tracks were up on the hill, my brother was at the bottom, I was in the middle, my friend was on the end farthest from the hill. Then we heard a lot of racket and looked over to my brother, he yelled my name in a really scared voice as something was going up over the hill. I remember seeing trees bending back as if being used to help something get up and over the top. When I got to where my brother was he was on one knee and had his gun pointed up at the hill. I said what was it and he said I DON'T KNOW, BUT IT WAS BIG. We found 2 marks on the really steep bank going up to the railroad tracks, I tried to climb it and could not. The marks were in the middle of the hill and at the top, something very strong and powerful went up the hill. It had a big stride also. The hill was about an 80% incline.