The Largest Wolf Of All Time Makes Even A Dire Wolf Look Small

Now living primarily on the screen and made popular by shows like "Game of Thrones," the dire wolf is more than just a work of fiction. It once existed and may have coexisted with gray wolves and humans on Earth before going extinct approximately 13,000 years ago at the end of the last ice age. The dire wolf would have cast an intimidating figure, weighing between 150 and 200 pounds and measuring 6 feet long. While impressively large, the dire wolf is considerably outsized by the Epicyon haydeni, a dog-like species that existed millions of years ago.

Eight feet long and standing at almost three feet at the shoulder, the average Epicyon haydeni would weigh between 220 and 276 pounds, though the largest ever found was a whopping 370 pounds. That is heavier than a full-grown male gorilla or an upright piano. These measurements put the ferocious ancient species at double the size of most dire wolves and triple that of many modern gray wolves that range from 60 to 145 pounds and 3 to 5 feet long.

Just as some dog breeds have gone extinct, the Epicyon haydeni went extinct around 12 to 6 million years ago. Modern humans would never have encountered the gigantic, intimidating figure. Still, the magnificent beast is undoubtedly a fascinating prehistoric creature, something those who have their own big dog at home will understand. Thankfully, science has been able to paint a picture of the life of the wolf-like giant.

Epicyon haydeni belongs to the Canidae family, which includes foxes, wolves, dogs, coyotes, jackals, and hyenas; the latter of which is believed to be descended from the ancient species. It is also part of the now-extinct subfamily, Borophaginae, which means "bone-crushing dogs". The intimidating family name is apt, as a hypercarnivore (living on a diet of 70% meat), it would have fed on a range of larger mammals, using its powerful jaws to bring down its prey.

Fossils of the Epicyon haydeni have been found throughout the United States, ranging from Texas to Montana. The first fossil was discovered in 1858 by Dr. Ferdinand Vandeveer Hayden, from which the big mammal gets its name. While it is unknown whether or not they hunted in packs, as an apex predator, the ancient canid would have been unlikely to have many other species prey on it. Still, it would have faced competition from other now-extinct species, such as the giant bear, Agriotherium, which weighed over 1,400 pounds.

Despite its size and strength, the Epicyon haydeni is believed to have gone extinct due to a tale that is as old as time: the rivalry between cats and dogs. Notably, the migration of other predators, such as the saber-toothed tiger (Smilodon), outpaced the bone-crushing dog when hunting. A declining food source led to fewer offspring, ultimately causing the once fearsome Epicyon haydeni to die out. While long gone, the giant canid showcases the remarkable process of evolution, from prehistoric wonder to the large dire wolf to our modern-day wolves and dogs.