Screaming or howling in Tarrant County, Texas

It was the Friday before Christmas, 1976. School was out that day. Everything is a blur except what happened that night at the Nature Center. It was called Greer Island then. My name is Robert. After work, I picked up the new kid in my class, Mike, and my best friend, Al, bought a 6 pack, and drove out to the lake roads. We drove north off of highway 199 and through the Nature Center to where we fished, called the bend in the river. Mike and I got out and were putting the batteries in the flashlights, while Al was in the truck with the music loud. We were talking in back of the truck watching the river running by and shining the flashlights. It was cold. We were facing north and we hear this "roar, scream, howl," behind us. It was so loud that I ducked foward, gritting my teeth, Mike grabbed my jacket and said "What the hell is that?" I said "We gotta get out of here.", and it does it again, "scream, howl, roar." It was echoing, and it felt like the the woods were shaking. Al lowered the radio while rolling down the window and said "Robert, what the hell was that?" As Mike I were getting in the truck, it does it again, "scream, howl, roar." It's loud and long and sounds mad as all get out. You could almost hear it taking a breath before it howled. By this time, I'm starting the truck and when my hand started to go to Drive, Al put his hand on mine and said "Whatever you do, don't wreck. Let's go." I knew this road real well, so we knew that after we're going about 50 mph, that we were safe. Nobody says a word till we stop at Hwy 199. and then we start saying "What was that?, What was that?"