The animal in this frame is descended from one of very few groups that were never wiped out.
North America held tens of millions of bison. By the late 1800s the continental population had been reduced to a few hundred animals, and the herd that survived inside what is now Yellowstone was one of the only wild groups to persist continuously on ground it had always occupied. Nearly every bison alive today traces back through a very narrow genetic bottleneck, and the Yellowstone animals are unusual in not carrying cattle genes from the crossbreeding experiments that went on elsewhere.
They are also genuinely wild, which visitors persistently fail to register. A bull weighs close to a ton, can run at thirty miles an hour, turns faster than a horse, and is responsible for more injuries in the park than bears are by a wide margin. Photographing one properly means a long lens and a great deal more distance than most of the people beside you on the road are keeping.