These bones were found just above Cretaceous gravel layer at a local DFW creek today. One the leg bones measures almost 17 to 18 inches in length. Leg bone width on this one is around 3 to 4 inches. I also found vertebra bone of bison as well. They look juvenile. These are probably either adult steppe bison bones or juvenile bones. Earlier this month, at a another creek, I also found steppe bison dorsal vertebra with rib bones within similar layer. Your opinion helps.