The American Lion

Panthera atrox image by Sergiodlarosa

I’ve spent most of my professional life looking at questions to do with the evolution and spread of the lion (Panthera leo). One of my most cited papers looked at the DNA from recent and Pleistocene lions and sorted them into three “types”.

1. The African and South Asian maned lion that we all know (Panthera leo ssp.).

2. The Cave lion (Panthera leo spelaea) from Pleistocene Eurasia (including Alaska and the Yukon Territory, which was connected by the Bering land bridge to Siberia at the time).

3. The American lion (Panthera leo atrox) which was found from Southern Canada down to Mexico

Of the three, we are left with the veritable runt of the litter. The Cave lion and American lion were enormous cats. Probably the biggest felids ever to evolve, with spelaea commonly cited as 20-30% bigger than modern lions. Atrox may have ranged up to 350kg, exceeded only (perhaps) by the South American Smilodon populator. The American lion is most famously known from the LA tarpit site of Rancho La Brea. It is also known from many sites ranging from Florida to Wyoming, and even Edmonton. It used to be thought that the American lion was found as far south as Peru, but these remains are probably from a large form of Jaguar which was around at that time. It’s notoriously difficult to separate the Panthera cats, once their skins are off. It has definitely been found in Mexico, at the site of  Chiapas, and this is probably as far south as they got. The heavily forested isthmus of Panama would have acted as an efficient barrier to what is and was, essentially, a cat of the open plain.

So what was atrox like? Can we make some general assumptions about the biology of this extinct cat? Based on the phylogeny, the American lion is simply an isolated and distinctive population of the Cave lion. Therefore, deductions about the Cave lion should probably apply to the American lion as well. We know that the Cave lion probably lived in prides like modern lions do. Most of the Pleistocene art from places like Chauvet cave and Lascaux cave show multiple lions interacting with each other. Cave art is probably a good indicator of life habits as behaviours we know about from observing modern lions are also found in depictions of Panthera spelaea. For example this image:

Shows what appears to be a male Cave lion (note prominent testicles under the base of tail) “hunkering down” to a female as a courtship gesture. Also note that the mature male does not have a mane- there are no depictions of maned lions in European Pleistocene art. The mane is probably a recent evolutionary innovation unique to the modern African/Asian lineage. So, American lions were probably maneless, pride dwelling cats too.

The last radiocarbon dates for this species overlaps with the first humans in the Americas. As well as dodging Sabretooths like Smilodon fatalis and Homotherium serum, and the giant bear Arctodus simus, you would also have to outwit super sized, cooperatively hunting, smart lions.