Battle royale: Prehistoric cave bears versus cave lions
Deep inside the bowels of a dark cave in central Europe, a noise rouses a fierce creature.
Sleeping on its bed, a giant cave bear opens one eye, alert to any intruder.
It stands, lifting its massive 400kg frame and bares its teeth.
In front of it is an equally sized cave lion; a giant predatory cat, and the cave bear's mortal enemy.
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Only one will survive, while the bones of the fallen will litter the cave floor for millennia.
New evidence reveals how such titanic struggles likely took place in caves across central Europe in the Upper Pleistocene epoch, which ended around 11,500 years ago.
While excavating caves in Germany and Romania, scientists have unearthed the bones of large numbers of cave bears, a now extinct species that stood bigger than today's grizzly bears.
The bears' bones, claw marks they left in the caves in which they lived, and even the beds they slept on, paint the best picture yet of how these magnificent creatures once lived.
But more than that, researchers have also uncovered the petrified bones of the cave bear's foe, the Pleistocene cave lion.
More than 25% bigger than today's African lions, the cave lion was itself an impressive predator, one that may have specialised in hunting cave bears for food.
Details of the two massive animals' remarkable battles have been released by palaeontologist Dr Cajus Diedrich of PaleoLogic, based in Halle, Germany.
"We have found spectacular things," he told BBC News. "Cave bear dens with skeleton remains, which [show] cave bears clearly were eaten by large predators."
Paws and claws
During extensive surveys inside, Dr Diedrich has discovered tens of thousands of bones belonging to several generations of cave bears, from young cubs to old animals.
End Quote Palaeontologist Dr Cajus Diedrich
Lions and hyenas ate the intestines and inner organs first”
The location of the bones reveals that the bears likely only entered the cave through the main opening and inhabited its drier areas.
He has also found several hundred tracks made by cave bears walking through the caverns, scratch marks on the walls made by bears and even hibernation nests the bears dug out to sleep on.
Well preserved foot prints are rare, and they can help establish the behaviour of the cave bears compared to modern brown bears or black bears.
For example, cave bears made much larger prints than those of its later relatives, and had short broad claws.
That suggests cave bears had dull digging claws like black bears, and were herbivorous. In contrast, brown bears are omnivorous and have sharp pointed claws useful for catching and killing small animals and fish.
"The feeding habits, diet and food-gathering behaviour of cave bears must therefore have been more similar to those of black bears than brown bears, with both cave and black bears using their claws more for scratching and digging," writes Dr Diedrich.
The footprints also reveal that the prehistoric bears wandered the cave's inner caverns, even walking down to a stream to drink, possibly during the time the bears were hibernating.
Scratch marks even indicate that very young bears lived inside, evidence that bears were born and raised in the cave.
Hibernation nests are better known from other sites, but few have been analysed in detail.
In the cave, known as Ursilor cave after its bear inhabitants, Dr Diedrich uncovered 140 cave bear beds, most oval-shaped and up to 50cm deep.
Scratch marks establish for the first time that the bears excavated these beds to sleep on, and there is evidence some even died in their sleep.
Dr Diedrich has found the skeletons of an adult and a one-year-old cub within their beds, the cub still in its sleeping position.
But it is the battles these bears fought with the equally impressive cave lions that is perhaps the most intriguing.
Three skeletons of cave lions have been found so far 800m deep within Romania's Ursilor cave.
The truth about lions
- European cave lions were a subspecies of the modern lion, which today exists in Africa, with a small population remaining in Asia
These remains overlap with the cave bear's territory, suggesting the lions had entered to hunt and kill bears.
Another cave, known as the Zoolithen cave near Burggeilenreuth, Germany has yielded a far more impressive hoard, however.
Dr Diedrich has researched the remains of 13 cave lions found in Zoolithen.
In the journal Historical Biology he describes how none were cubs, suggesting that cave lions, like their modern African relatives, didn't also raise their young inside the rocky caverns.
Crucially the lions were mostly older males, reinforcing the impression that only the bigger males entered the caves, supporting the idea they did so to hunt bears.
Or it could be that whole prides entered, with the adult males doing most of the fighting.
The cave lions may have targeted the bears after their usual prey, mammoth and woolly rhinoceros, disappeared.
Hunters become victims
Backing this idea are two cave bear skulls found within Zoolithen cave, which have been marked by lion's teeth.
Also found are the skeletons of giant hyenas, which also frequented similar Pleistocene caves.
They suggest that lions and hyenas also did battle, with some of these lion remains being dragged into the caves by giant hyenas, packs of which either killed the lions of scavenged their carcasses.
And hyenas may have scavenged cave bear bodies.
"Lions and hyenas ate the intestines and inner organs first," says Dr Diedrich.
But they also strongly suggest that some cave lions lost the fight with cave bears.
Being herbivorous, the cave bears wouldn't have scavenged the bodies of any lions they killed.
Instead they would have just trampled them into the cave floor, leaving the evidence we see today of these titanic struggles.