To trace the roots of prehistoric carnivores and herbivores, we must first bridge the gap between their ancient past and our present.
Imagine the African bush elephant, a sun-baked behemoth lumbering across the plains and craters of present day Ngorongoro. Standing at an impressive height of nearly 13 feet, capable of reaching lengths of 24 feet, and often weighing more than seven tons, this beast has become the largest and heaviest land animal on the planet.
It’s hardly a surprise that a mammal so robust doesn’t need to worry about impending threats from natural predators. Aside from a coordinated pride of lions (and their number would have to be many), or perhaps a particularly ferocious gathering of crocodiles, this variety of elephant will remain virtually unscathed for a lifespan that can stretch to upwards of 70 years.
That’s a long time for any animal, and especially for a species with no real comeuppance in the food chain. In fact, aside from humans, the African bush elephant lives far longer than any other mammal.
This can pose a serious problem for the surrounding ecosystems. In the course of a single day, one of these elephants will consume nearly 350 pounds of vegetation. And although some scientists posit that certain limiting factors–such as falling nutrient levels in plants–will inevitably regulate populations, the elephantine growth remains a constant.
So what about 15,000 years ago, when the planet was inhabited by much larger varieties of herbivores? How could the biosphere possibly sustain itself when mastodons, giant ground sloths, and Columbian mammoths roved the wilderness, devouring entire ecosystems of vegetation in their wake?
Lest we forget, nature always finds a way to sustain the greater cycle. Its answer? Hypercarnivores.
Rewinding back two million years, all the way up until only around 11,000 years ago, lands us squarely in the Pleistocene epoch. It’s an age of great interest to both scientists and paleontologists alike, thanks to the incredible diversity of species it boasts. While megaherbivores such as the aforementioned mastodons and mammoths scoured the land and threatened to overgraze, hypercarnivores served as the sole source capable of mediating their populations.
Simply put, a hypercarnivore is a species whose diet is greater than 70 percent meat. In most cases, however, the figure extends upwards of 90 percent. Today, lions and tigers who only consume meat are considered hypercarnivores, as are wolves and polar bears (the only type of bear to qualify).
But while these brutes are certainly considered deadly and formidable opponents in the wild, their ancient ancestors dwarfed them by comparison.
Blaire van Valkenburgh has dedicated her life to studying these ferocious beasts of yesteryear. As a paleontologist and Professor of Ecology and Evolutionary Biology at UCLA, Valkenburgh uncovers Pleistocene-era teeth and examines them to determine exactly how these predators survived.
“For a while, scientists would often underestimate how much larger these predators were compared to modern ones,” Valkenburgh explains. “Take lions, for instance. In the old world, they were at least 50 percent larger than the biggest ones alive today.”
To put matters into perspective, imagine a typical gray wolf. The males clock in at a standard of 95 pounds, with dense and bushy tufts of hair to help with insulation during frigid winters. To the untrained eye, they could resemble little more than a wild dog.
You’d be hard-pressed, however, to confuse our canine friends for the gray wolf’s hypercarnivore ancestor–the dire wolf. Not only were their teeth larger, and their bites 129 percent the force of a gray wolf, but they could also weigh close to 175 pounds (probably attributed to their steady diet of horse meat). A stocky build, powerful bite, and ruthless pack hunting tactics rendered them formidable opponents against mastodons and even saber-tooth tigers.
Speaking of their feline counterparts, the saber-tooth tiger (technically known as Smilodon fatalis) has persisted as perhaps the most iconic killing machine of the Pleistocene era. The curved fangs of this megafauna mammal have forever etched its place into our collective fears and imaginations. And if the tooth length alone (close to 12 inches) isn’t enough fodder for lasting nightmares, then consider this: they could also open their jaws up to 120 degrees wide–a snake-worthy feat that doubles the capability of today’s lions.
The teeth are of particular interest to Valkenburgh; without them she wouldn’t be able to accurately assess the size of prehistoric carnivores. For species with only scant fossil evidence available, she employs an entirely different method of identification.
“In those instances, you have to use modern animals,” she tells BTR. “For example, the size of a first lower molar is a pretty good predictor of body mass in living species–so you can make a linear model of that.”
Using the same equation and applying it to a fossil’s lower molar can then provide a close estimate of body size.
It’s hard to imagine what creature could possibly be capable of causing the extinction of such deadly predators. The answer, it turns out, isn’t bigger or faster carnivores.
It’s us. Or, rather, our Neanderthal ancestors.
“It’s very impressive that our ancestors were able to deal with and survive in the midst of all these large carnivores,” says Valkenburgh. “Part of our ability to out-compete with them stems from our domestication of wolves.”
She explains how these wolves (or proto-dogs) might have lingered on the outskirts of human encampments at night–utilizing their heightened senses of smell and hearing to alert their masters to the presence of prowling saber-toothed tigers.
It’s hardly a coincidence that patterns of extinction amongst the large carnivores coincide with the arrival of intelligent hominids. In some manner, this kind of regulation might have been necessary in an environment filled to the brim with domineering super carnivores. However, this cycle of dominance and decline raises a new, ineludible question:
Who’s left to regulate us?
Feature photos courtesy of Wikimedia Commons.