Bison antiquus, sometimes called the "ancient bison", was the most common known large herbivore of the North American continent for over ten thousand years, and is a direct ancestor of the living American bison. B. antiquus was taller, had larger bones and horns and was 15-25% larger overall than modern bison: It reached up to 2.27 m (7.5 ft) tall, 4.6 m (15 ft) long, and a weight of 1,588 kg. From tip to tip, the horns of B. antiquus measured approximately 3 feet (nearly one meter).