From Tar Pits to Game of Thrones: The Hidden History of the Dire Wolf
By Kyle Hill on June 1, 2014
North of Castle Black, far beyond the Wall, dire wolves roam. Paws press heavily into winter snow as the ferocious hunters scour the wilds for food and shelter. When winter finally comes to the rest of Westeros, maybe their range will extend south towards King’s Landing and put pressure on townsfolk to keep their children and cattle a little closer at night. Wolves the sizes of ponies aren’t easily fended off, after all.
The sigil of House Stark, Game of Throne’s dire wolf is the hunter of the north. But that’s where they stay. According to Theon Greyjoy, dire wolves had not been sighted south of the Wall for two hundred years, until Robb Stark found a litter of six pups romping around near their dead mother. History tells another story.
Game of Thrones has made the dire wolf famous 10,000 years after the last real one died. And though they lived to the end of the last ice age, you wouldn’t find one stalking in the snow and ice—dire wolves would be as disappointed north of the wall as the Night’s Watch. We know this from thousands of skulls and bones uncovered from bubbling pits of tar.
Canis dirus, or “dire wolf,” was a large canid that hunted in North and South America for about 1.8 millon years, going extinct with other megafauna around 10,000 years ago. Where we find their fossils suggests that the wolves’ habitats included grasslands, tropical marshes, and temperate forests, but not unyielding snow and ice. In fact, a dire wolf specimen has never been recovered further north than Alberta, Canada.
Dire wolves are the largest known species of Canis, a genus that includes wolves, dogs, dingoes, jackals, and coyotes. A formidable five feet long and 175 pounds, the dire wolf wasn’t much larger than the modern gray wolf. But the dire wolf was much stronger, based on its bones. The more robust skeletons that we find imply that the dire wolf was much more muscular than any canid walking the Earth today, and had a bite equivalent to 36 atmospheres pressing down on one square inch of flesh.
The dire wolf was a hyper-carnivore, adapted to take down whatever megafauna were available—such as bison and giant ground sloths. This affinity for large, easy prey could be why so many dire wolves joined in a gooey demise near modern day Los Angeles.
You can smell the La Brea tar pits before you see them.
Less than ten miles from the heart of Los Angeles, where once crude oil and methane bubbled up into ice age air, now sits the Page Museum. I was headed there on a blistering summer day to see the ooze that captured more ice age species than any other fossil deposit on Earth. Out of all the vertebrae fossils there, most of them are dire wolves.
I walked past numerous school groups sitting and playing on the park grass that surrounds the Page Museum and towards the main building with the distinct smell of freshly laid road filling my nose. Once inside the main building, Lead Gallery Interpreter Anya Hunter and Coordinator of School Programs Kelsey Ziff met me with a kind hello. I asked where all the tar was, unable to see the gurgling pits I had imagined on the way in. “It should be called ‘the asphalt seeps,’” said Ziff, “But no one would come if we called it that.”
Stay in California long enough and you’ll learn of its geologic faults. Deep, long cracks in the Earth criss-cross much of California, and the La Brea tar pits are no different. The 6th Street Fault, just a few miles from the Page Museum, has been leaking for thousands of years, unlocking fossil fuel created long before dire wolves ever showed up there. This crude oil and sediment (the “tar”) eventually reaches the surface, where more volatile chemicals in the oil evaporate off and turn the goo into hardened asphalt. If you dig a little bit, you can still get at the tar. The picture-perfect bubbling that you can see at La Brea is from bacteria decomposing the oil and belching methane.
“The word ‘ooze’ comes to mind,” says Ziff.
And it’s easy to imagine this ooze consuming animals like black quicksand—mammoths trumpeting as tar inched up their hairy legs until even their trucks were filled. But death-by-tar pit isn’t quite so dramatic; it’s boring. Animals that do get stuck in the stuff sink a few inches and stay there. “Basically, they get trapped as though on fly paper, completely exposed to the surface,” Hunter explained to me.
These “entrapment events” account for the large number of fossils at the tar pits, and the large number of carnivores. When an entrapped animal cries to its herd or just out of frustration, it attracts predators looking for an easy kill. “And then the predators get stuck in the asphalt seep as well,” said Hunter. It’s like a frog getting its tongue impossibly stuck on flypaper. However, entrapment events didn’t always end in bloodshed. “Sometimes it was just thirst and starvation because the animals couldn’t get away.”
The tar pits at La Brea get a lot of attention for its large mammals—who doesn’t want to inspect a saber tooth?—though the area is a gooey catalogue of a whole ancient ecosystem. That’s thanks in large part to the incredible preserving properties of tar. Go to another museum and look at the fossils and chances are those fossils are stone. This is because bones lucky enough to be fossilized have much of their structure mineralized, or replaced with minerals. Tar works differently. Instead of minerals replacing the organic matter of the bones, a tar pit’s oil and other hydrocarbons seep into the skeletons and preserve them. The fossils you see at the Page Museum are actually still bones, not rocks.
Researchers take advantage of the tar’s preserving qualities to learn more about the tar pits and the organisms found there. For example, fossilized insect larvae found inside the bones of entrapped animals can tell scientists how long an animal was exposed to the open air before more tar covered its corpse. “We have blowfly eggs from the bones of bison, and it teaches us about how long those animal remains were exposed to the surface,” Ziff told me. The museum has also uncovered a number of plant species in the muck, the extant species of which have been planted in the museum’s garden.
Everything preserved in the tar is something that can tell scientists what the conditions were like thousands of years ago. Even animals interactions stay in the ooze. “Whether it’s a wolf that got kicked in the face by a bison or a saber-toothed cat with back problems…it’s like we have a time machine!” Kelsey exclaimed.
“We have answers to questions we haven’t even asked yet.”
Hunter and Ziff lead me through the museum floor to a wall of skulls that were missing their jaws. All in all, the massive orange-lit case displayed 402 dire wolf skulls. They were detailed enough to see wear and tear on teeth and healing bone fractures. Each skull was a distinct brown color, something I did not expect considering that almost all museum specimens you will see are bleached white. Hunter and Ziff call it “La Brea brown”—a consequence of bones fossilized with crude oil.
Out of all the fossils found at La Brea, 90% of them are of carnivores, and most of those are dire wolves. Over 4,000 dire wolf specimens have been uncovered here, with the next most found fossil being saber-toothed cats with over 2,000 specimens. The dire wolf population at La Brea was large—what you might expect it to be like in Game of Thrones, north of the Wall. But researchers have excavated so many dire wolves here exactly because the ancient California climate was nothing like Craster’s Keep.
Dire wolves, along with other North and South American megafauna like saber-tooted cats and woolly mammoths, died out at the end of what geologists dub the Pleistocene, an epoch that lasted from 2.5 million years ago to just over 10,000 years ago and spanned the Earth’s most recent ice ages. Though the timing was right, it turns out that the dire wolf preferred its ice age habitat without much ice. At the Pleistocene La Brea, it was only ten degrees cooler on average than the 100 degree Fahrenheit summer heat I had walked through to get to the Page Museum. This favorable climate attracted large animal migrations, bringing more carnivores like the wolves.
Climate and habitat brought the wolves, and the tar pits trapped them there.
Leaning in towards the wall of skulls, I pointed to a hole near the top of a larger one. There was a spongy part of bone that looked different than the surrounding tissue creeping inwards to cover the hole. Ziff and Hunter explained that the change in tissue probably shows a partially healed head wound, something that presents itself better in carnivores that hunt in packs or have some kind of social structure.
Dire wolves hunted in large packs, which we know partially from how many specimens are at La Brea. Because of the similar morphology and bone structures that dire wolves have in common with modern gray wolves, researches suspect that they hunted in similar ways. “Dire wolf remains have many of the same kinds of injuries and wear at their muscle attachments that their modern ancestors do,” Hunter told me. These bone pathologies also show healed injuries, which suggest a pack structure allowing injured wolves to be taken care of until recovered. If a non-pack hunting cheetah breaks a femur, for example, that is almost certainly the end of that cheetah. Dire wolf bones suggest that individuals survived long enough to heal injuries and hunt again.
What you won’t find at Le Brea also supports the pack-hunting hypothesis. Hunter explained that for as many skeletons of adult dire wolves are in the collection, there aren’t very many preserved pups. “This suggests that they had a social structure that allowed for some wolves in the pack to be sent out hunting while others stayed home.”
If the dire wolf was so strong, so organized, and only recently extinct, I asked Ziff, why did they die out? She chuckled and replied: “If it was on Facebook, it would read ‘It’s complicated.’”
If she had to choose, Ziff said that the wolves, though undoubtedly formidable, weren’t the apex predators at the end of the most recent ice age—the cats were. Smilodon, most likely the animal you envision when you think of a saber-toothed cat, was a ferocious predator competing with the dire wolves for megafauna in the same environments. Ziff would take a Smilodon over Canis dirus any day. Hunter took the side of the wolves. “I bet a hardy male dire wolf could take down a saber-tooth cat with weak hips,” she contended. However, both agree that another cat, Panthera leo atrox—the so-called American lion—was the ultimate terrestrial hunter of the age.
The dire wolf had stiff competition from other megafauna for the same prey, but smaller animals competed with the wolves as well. During the late Pleistocene and up until the dire wolf’s extinction, the gray wolf migrated across the Bering Strait land bridge into the Americas to challenge the dire wolves even further. Both hunted similar prey in similarly large packs. Dire wolves also had to deal with smaller carnivores like coyotes. Gray wolves and coyotes still roam the Americas today, perhaps because they weren’t picky eaters.
Competition is only a problem when there isn’t enough food to go around. Changes to the climate at the end of the last ice age could have changed herbivore populations enough that the dire wolves were out-competed by the big cats or smaller carnivores with more varied diets. Human intrusion also could have contributed to the wolf’s demise, hunting the same massive herbivores like wooly mammoth and bison. With their primary prey gone, the dire wolf was probably forced to compete more directly with faster and ultimately more adaptable species like the gray wolf, and was forced to scavenge.
When the prey was gone, or when the climate changed too much, or when the humans encroached too far, or maybe all of the above, the dire wolves went too.
At the end of my visit to the Page Museum, having learned so much about the ancient wolves in my own backyard, the question that first drew me to La Brea finally made sense to ask: Is Game of Thrones’ dire wolf depiction even close? Did ancient history ever have a “Ghost”?
“Their depiction is pretty standard as far as fantasy depictions of dire wolves, like J.R.R. Tolkien’s ‘wargs’,” Ziff explained to me. “But dire wolves are a lot smaller than what fantasy seems to think.”
Ancient dire wolves looked more like modern day gray wolves than the monstrous canines the Starks cared for, but much more robust. Dire wolves were stockier and more muscular, a feature that explains the wolves’ incredible estimated bite strength. As for size, a big dire wolf would probably have shoulders that barely reached your hips.
“[Visitors] come here and want to know why they’re so small,” Ziff told me.
Standing there in the museum, looking at wolf skulls and dire dioramas, I realized that whether or not Game of Thrones’ wolves are too big or too mean wasn’t really important. The point was that a TV show got me to go into a museum just to learn more about an extinct species, to learn more science. It turns out that many museum visitors have done the same since Game of Thrones first aired.
Ziff thinks that it is a combination of alien and familiar that makes the dire wolf so interesting. “It’s almost believable that in some distant land that there could have been these huge mega wolves walking around.” Dire wolves feel more real than fanciful dragons, in other words. The canid is close enough to reality that making it a bit larger or more ferocious isn’t breaking any conceptual barriers, and sticks with us.
Game of Thrones dire wolves are so popular because we can effortlessly exaggerate today’s wolves. “It’s like Superman: he looks like a human but he can punch through a wall,” Hunter thinks. “That’s easier to do with something familiar.”
The pop culture interest in dire wolves spearheaded by Game of Thrones has translated to a real uptick in scientific interest for the museum. Every day, Hunter and Ziff see museum visitors who want to know about the large wolves that lived right in their backyard just a geologic blink ago. “People are interested to know that dire wolves and saber-toothed cats used to walk in the park that they just walked through,” says Hunter.
Scientists and researchers working at La Brea are happy to tell the true story of the dire wolf no matter why visitors are there. But the resurgence of interest in the ancient canids isn’t a one-way street. Just before I left the Page Museum, Hunter and Ziff wanted to show me something special. Behind a large, semi-circular glass window, they pointed inside the museum’s researcher lab, at boxes filled with characteristic “La Brea brown” bones waiting to be cleaned and classified. Dubbed their “Fishbowl Lab”, it looked like a regular museum research room before I slipped behind the barrier for a closer look.
Out of the handful of boxes containing dire wolf bones, one was clearly labeled “Ghost”.
Kyle Hill is the Science Officer of the Nerdist Enterprise. Follow the geekery on Twitter @Sci_Phile.