Giant Bison

The Giant Bison skeleton stands at just over 2 meters from the floor to the top of the tallest vertebral spine. In life, this animal would have stood about 2.5 meters tall, with horns at least 2 meters wide (Royal Saskatchewan Museum).

Scientific Name

Bison latifrons

Scientific Classification

• Phylum: Chordata
• Class: Mammalia
• Order: Artiodactyla
• Family: Bovidae

The giant bison became extinct sometime between 21,000 and 30,000 years ago. It ranged widely across what are now the United States and southern Canada. The modern American bison (Bison bison) is considered the quintessential American mammal, with an estimated population of 60 to 100 million bison roaming North America before the arrival of Europeans. As settlers moved westward, they ravaged bison herds, pushing the species to the brink of extinction. Fortunately, with protection, strong populations of bison now exist in several national parks in the United States and Canada, as well as on private ranches.

The bison we know today is one of the last vestiges of American megafauna. These lands were home to several different kinds of bison, all of which originated from animals that migrated into North America from Asia via the Bering land bridge. It remains unclear whether these fossils represent distinct species or variations of one highly variable species of bison. The ancestors of bison evolved in Eurasia about 2 to 3 million years ago, spreading to North America approximately 300,000 years ago. This continent, rich in opportunity, allowed these ancestral bison to diversify into various forms, the most impressive of which was the giant bison.

While modern plains bison are substantial animals, with males reaching 2 meters at the shoulder and weighing 900 kg, they would be dwarfed by a giant bison, which stood around 2.5 meters at the shoulder and could weigh as much as 1,800 kg. The giant bison also had incredible horns. Like all bovids, its horns consisted of a core of bone surrounded by a keratin sheath, which rots away after being buried for thousands of years, leaving only the bony cores. Some of these skulls exhibit a horn span of just over 2 meters, but in life, the keratin sheath would have made the span even wider, as demonstrated by a Californian specimen where the outer sheaths were replaced by sediment casts.

Modern male American bison are significantly larger than females, but this sexual dimorphism was even more pronounced in the giant bison. A fully grown male giant bison, with its massive, shaggy forequarters and tremendous horns, would have been a striking figure compared to much smaller females.

The living bison is classified into two subspecies: the plains bison (B. bison bison) and the wood bison (B. bison athabascae), with the latter exhibiting similar behavioral traits. It is believed that the giant bison did not live in the large herds characteristic of plains bison; rather, it may have formed small, close-knit family groups. Fossils of the giant bison have been found across a wide geographic area, indicating that the animal could thrive in various habitats, including forests, parklands, and steppe grasslands, where it grazed on a diverse range of plants.

The exact purpose of the giant bison’s massive horns remains unclear, but they were likely important during the breeding season. Males probably fought for access to females, although it is possible that those with the most impressive horns could avoid conflict through display, intimidating rivals with their size. Pleistocene North America was home to a diverse array of predatory mammals, many of which could challenge a giant bison. Larger saber-toothed cats, American lions, and pack-hunting wolves could overpower a fully grown giant bison, but tackling an adult male, armed with vicious horns and great strength, would have been perilous. Thus, predators likely focused on calves or old and sick adults.

The giant bison seems to have vanished before humans arrived in North America, but it likely did not go extinct in the typical sense. As the giant bison adapted to the changing American landscape, it evolved into the smaller species known as the ancient bison (Bison antiquus), which lived between about 20,000 and 10,000 years ago and eventually gave rise to the modern bison. Mitochondrial DNA recovered from Bison antiquus shows a close relationship with modern bison. Although no DNA has yet been extracted from giant bison fossils, a clear reduction in size from the giant bison to the ancient bison and then to the modern bison illustrates evolutionary change.

The first humans to colonize North America, known as the Clovis culture, were likely familiar with the ancient bison—descendants of the giant bison. By Clovis times, around 13,000 years ago, ancient bison were grassland animals with swelling numbers. Hunting an adult bison probably provided small groups of humans with enough food for weeks, along with raw materials for tools, shelter, and clothing. However, it is unlikely that human hunting caused the extinction of this bison. As with many of North America’s great beasts, we cannot attribute their disappearance to a single event or cause.

For nearly the last 2 million years, Earth’s flora and fauna have had to adjust to substantial climatic changes, some occurring abruptly, such as glaciations and their associated interglacials. These changes have most significantly impacted low latitudes, yet animals have been able to move in response to deteriorating conditions, even at the cost of reduced populations. Alongside the entry of humans into North America, climate change had already led to a reduction in the giant bison’s size, evolving into the smaller modern bison.

Hunting likely impacted bison populations, but they were unique in their ability to endure these pressures and even expand their numbers until the advent of firearms nearly drove them to extinction in the nineteenth century. It has been inferred that the bison that crossed into North America from Asia were steppe bison (Bison priscus), which were ancestral to the giant bison and gave rise to the two American bison subspecies we recognize today.

In the United States and Canada, archaeologists have unearthed what appear to be kill sites—locations where the first Americans processed ancient bison for their meat, skin, bone, and sinew. Some of these sites have yielded remains of hundreds of bison, highlighting the animals’ importance to the survival of prehistoric humans in North America.

A species of bison also survives in Europe: the European bison, or wisent (Bison bonasus), a forest-dwelling animal that once roamed much of Eurasia. Over-hunting reduced its population until the last wild specimen was killed in 1927. Fortunately, several wisent were kept in zoos and private collections, allowing for a reintroduction program. Today, thanks to these efforts, the largest European land animal can be found in several eastern European countries.