During the later parts of the last Ice Age, the Americas were home to several different species of large cats. These included familiar faces like cougars and jaguars, as well as the fearsome sabre-toothed cats. But they were not the heavyweights of these cat-covered continents — that title goes unequivocally to Panthera Atrox: the American Lion.

Scientists hope that studying these huge kitties can give us insight into the dramatic ways our world has changed in the recent past — and in turn, help us predict how it might continue to change in the near future. As far as extinct species go, we have a good amount of intel about American Lions. Fossils have been found at over 50 sites from all over the continents, which date as far back as 2000 years.

We even have skulls from multiple sites. And the Rancho La Brea area of Los Angeles — home to the famous La Brea Tar Puts — has yielded the fossils of more than 80 individuals, including lots of skulls and other body parts to examine. All these fossils have taught us a lot about these animals. Like, for example, that they were really big.

The largest cats I’ve today are Siberian tigers, which max out at around 250 to 300 kilograms. Estimates vary for American Lions, but it’s generally thought that big males could grow well over 400 kilograms!

So they were some of the biggest cats ever, and possibly the biggest. In Ice Age North America, the only predators that outweighed them were giant short-faced bears — which weighed up to a ton.

Scientists have even extracted DNA from American Lions fossils! And when they compared those sequences to other cats, past and present, they figured out that Panthera Atrox split from the now extinct cave lion over 300 thousand years ago. So, we’re pretty sure we know how they got to the New World: most likely, a group of cave lions crossed the Bering Land Bridge from Asia into North America.

Some made themselves at home up in the Yukon area, while others moved south, eventually becoming American Lions.

But even with all the fossils, we have of these ginormous cats, there are some enduring mysteries — like what exactly they were up to here. Palaeontologists are somewhat confident that they roamed the plains.

That’s because they had relatively long legs, which is similar to Modern-day African lions that are specialized for the Savannah, but different from many cats, including their cave lion ancestors. And they might have stuck to the grasslands to avoid competition with the resident woodland predators: those terrifying sabre-toothed cats. But what exactly they ate and how they obtained it are still unclear.

Which would have included horses, bison, and even baby mammoths! And that’s only if they hunted solo. If they worked in groups as modern lions do, the study estimated they could have taken down 6 thousand kilogram prey.

That means giant ground sloths and even adult mammoths could have been on their menu! But here’s the thing: even though lions alive today hunt in groups, and there’s evidence that suggests cave lions might have too… we don’t know if American Lions did. We know they had particularly large brains, even considering their size. But big brains don’t necessarily mean social hunting. After all, modern-day tigers have bigger brains than lions, and tigers hunt alone.

And that could indicate that young males were roaming on their own while females stuck with a group, as we see in African lion prides today. So, maybe this is evidence of group living. But it’s hard to know for sure without finding, like, a perfectly fossilized pride, just like, covered in ash and waiting there for us to find it. Whatever they were doing, American Lions went extinct towards the end of Ice Age.

The youngest American Lion fossils anyone has found are around 11000 years old. The question of what caused this extinction is one of the longest-running debates in palaeontology.

It’s generally thought to be some combination of a warming climate and the global spread of humans. But more research on American Lions could give us some finer resolution there — like why they didn’t make it through when cougars and jaguars did. That resolution could help us figure out how to keep their smaller cousins from sharing their fate.

Ultimately, that’s why palaeontologists put so much effort into studying creatures that disappeared long ago. They hope they can learn from the past. That this learning means studying one of the most impressive animals to ever have existed? Just a bonus.