How Jaguars Survived the Ice Age

A jaguar at the St. Louis Zoo. Photo by Brian Switek.
A jaguar at the St. Louis Zoo. Photo by Brian Switek.

The mastodons, ground sloths, and sabercats are all gone. They all slipped into extinction around 10,000 or so years ago, along with an even wider variety of fantastic beasts and birds that fall under the category “megafauna.” But not all the Ice Age megamammals died out. We spend so much time mourning the losses that we often forget the survivors that carry whispers of the Pleistocene world. Among these resilient beasts is the jaguar.

Jaguars are old cats. They first evolved in Eurasia sometime around three million years ago before spreading both west and east, eventually inhabiting a range from southern England to Nebraska and down into South America. Today’s range of southern Arizona to Argentina—over 3.4 million square miles—is only a sliver of their Ice Age expansion. And it wasn’t just the jaguar’s range that shrunk. Today the spotted cats are about fifteen percent smaller than their Pleistocene predecessors.

Nevertheless, jaguars survived while the American lion, the sabercats, and other predators vanished. How? In order to investigate this question, biologist Matt Hayward and colleagues looked at the jaguar diet and how the cat’s prey preferences changed over time.

Drawing from 25 published studies documenting 3,214 jaguar kills, Hayward and coauthors found that jaguars are pretty finicky for apex predators. The big cat’s menu spans 111 species—ranging from cattle to rodents to monkeys to turtles—but, contrary to what has often been written about the cat, the jaguar is not really a generalist that hunts anything and everything.

The most common parts of the jaguar diet, Hayward and colleagues found, are capybara, wild pig, caiman, collared peccary, nine-banded armadillo, giant anteater, and white-nosed coati. These species account for 16-21% of the jaguar diet. The stats also showed that prey including peccaries, brocket deer, giant anteaters, and coatis which were hunted 85% of the time when they were present in the jaguar’s range. Crunching the numbers a bit further, the zoologists found that jaguars seemed to especially target capybara and giant anteater. On the other hand, jaguars never preyed upon tapirs and almost never touched primates.

Jaguars come out of all this as a paradox. They are burlier than leopards, yet they prefer to hunt a narrow range of prey that falls in the shallow end of what jaguars should be able to tackle. This might have something to do with why the cats have shrunk. Jaguars aren’t large enough to take on tapirs alone, yet human hunting on mid-range prey—such as deer—has made such herbivores too rare to rely upon. So despite their size, jaguars responded by picking out smaller prey which Hayward and coauthors dub “suboptimal” for what the cats initially evolved to do.

The jaguar’s not alone in this. Coyotes have gone through similar changes. The scrappy canids are Ice Age survivors, too, and they were significantly larger during the Ice Age. When all their competition disappeared, coyotes became smaller and ended up living on the fringes in a world heavily influenced by humans.

Flexibility made all the difference for these carnivores. Even though jaguars no longer prowl as much of the world as they once did, and are currently listed as “near threatened” on the IUCN Red List, they were able to persist where so many other carnivores perished by shifting their diets. “It may be that jaguars survived this mass extinction event by preferentially preying on relatively small species,” Hayward and coauthors write. The fossil record of cougars tells a similar story: By eating parts of carcasses other cats didn’t want, mountain lions were able to survive the tough times. And even though the cause of the loss of many Ice Age celebrities remains debated, the survivors are truly the animals we should be looking at in greater detail. How they succeeded may hold the secrets to why so many other species failed.


Hayward, M., Kamler, J., Montgomery, R., Newlove, A., Rostro-García, S., Sales, L., Van Valkenburgh, B. 2016. Prey preferences of the jaguar Panthera onca reflect the Post-Pleistocene demise of large prey. Frontiers in Ecology and Evolution. doi: 10.3389/fevo.2015.00148

Did Sabercats Have Spotted and Striped Coats?

A Smilodon angles to get a better bite on a sloth at the La Brea Tar Pits and Museum. Photo by Brian Switek.
A Smilodon tries to get a better bite on a sloth at the La Brea Tar Pits and Museum. Photo by Brian Switek.

As far as fossil cats are concerned, there is no greater artist than Mauricio Antón. He has a knack for capturing the essence of fossil felids – be it a Homotherium pinning its prey or Dinofelis taking a cat nap – and I love that so many of Antón‘s illustrations feature spots and stripes. The sabercats I saw in books and stop-motion documentaries were never so colorful. They always seemed to wrapped in a relatively plain, dun-colored coat, making Smilodon look like a lion with abnormally-long canines.

Unfortunately, short of finding a frozen sabercat comparable to the steppe lion kittens announced earlier this year, we’ll  probably never know the precise span of sabercat shades. But maybe we can narrow the field a little. Today’s cats, both big and small, might be able to help us predict the presence of spots and stripes in their toothy, extinct relatives.

Today’s cats wear a beautiful array of coat patterns, from plain to dense constellations of spots and stripes. These different color options are largely dictated by two genes – Taqpep and Edn3 – the first of which lays down the general pattern of spots and stripes while the second controls local color differences, like hair banding. But these patterns don’t follow family lines. Just have a look at Panthera, the genus that includes most of the classic big cat species. There are lions (spots giving way to “plain” coloration), jaguars (large, filled-in spots), leopards (large open spots), snow leopards (large open spots), and tigers (vertical stripes) all within the same genus. Something else is more important than felid family ties in determining coat colors, and, in a 2010 study, ethologist William Allen and colleagues suggested that the answer is “ecology.”

After pulling images of 35 wild cat species from the web – because what else is the Internet good for other than cat pictures? – Allen and coauthors analyzed how coat patterns related to different species’ habitat preferences and activity patterns. Cat coats, they realized, “function as a background matching camouflage.” Cats in open, well-lit environments are more likely to have relatively plain coats while those living in forested habitats or active at primarily at night typically have complex patterns of spots and horizontal stripes.

Cats in open environments are more likely to have "plain" coats. Photo by K. Fink.
Cats in open environments, like mountain lions, are more likely to have “plain” coats. Photo by K. Fink.

There are some exceptions to this rule. Cheetahs, servals, and black-footed cats have spotted coats despite living in the same type grasslands as lions, while the elusive bay cat has a mostly-uniform coat despite prowling forests. Maybe these discrepancies have something to do with “microhabitats” or some sort of behavior not parsed out in the study, Allen and colleagues wrote, but for the most part a cat’s coat is more influenced by its ecology than who its related to.

The same probably held true for the sabercats. So while the forest-dwelling Dinofelis would be more likely to bear spots and stripes, Homotherium and other open-country cats may have lost their spots to be less conspicuous out in the grasslands.

So what about Smilodon? The cat is the ambassador for its long-fanged relatives as well as the Ice Age in general. While we may never know for sure, places like La Brea – where the sabercat is found in abundance – suggest that the iconic sabercat frequented shrubby chaparral. If the ecological connection held, therefore, Smilodon may have worn more subdued hues like the modern mountain lions that live in southern California today, or perhaps it was decked in solid spots much like the cheetah, serval, black-footed cat trio in Africa.

Despite its common nickname “saber-toothed tiger”, though, we can be pretty sure Smilodon didn’t have vertical stripes. Not only are sabercats and tigers distant relatives, but, as Allen and colleagues found, tigers are the only cats to have vertical stripes on their flanks. Perhaps the best we can hope for is that some Pleistocene artisan somewhere was inspired enough by the fossil cats to record their pelage palette for us to envision as Ice Age world that we just missed.


Allen, W., Cuthill, I., Scott-Samuel, N., Baddeley, R. 2011. Why the leopard got its spots: relating pattern development to ecology in felids. Proceedings of the Royal Society B. doi: 10.1098/rspb.2010.1734

Kaelin, C., Xu, X., Hong, L., David, V., McGowan, K., Schmidt-Küntzel, Roelke, M., Pino, J., Pontius, J., Cooper, G., Manuel, H., Swanson, W., Marker, L., Harper, C., van dyk, A., Yue, B., Mullikin, J., Warren, W., Eizirik, E., Kos, L., O’Brien, S., Barsh, G., Menotti-Raymon, M. 2012. Specifying and sustaining pigmentation patterns in domestic and wild cats. Science. doi: 10.1126/science.1220893

Ortolani, A. 1999. Spots, stripes, tail tips and dark eyes: Predicting the function of carnivore colour patterns using the comparative method. Biological Journal of the Linnean Society. 67: 433-476

When Lions Abound, Hyenas Pick a New Menu

Hyenas and a jackel at a lion kill in Kenya. Photo by Roger Smith,
Hyenas and a jackal at a lion kill in Kenya. Photo by Roger Smith, CC BY-NC 2.0.

For as long as there have been lions and spotted hyenas, the carnivores have competed with each other. The gore-flecked conflicts over carcasses on the African grassland are just the latest skirmishes in a carnivoran competition that has been going on since the Pleistocene.

I root for the hyenas. There’s something strangely charming about the tittering predators, and their dining habits are incredibly flexible. Despite their public image as desperate scavengers, clans of hyenas are capable of taking down prey as large as juvenile elephants as well as reducing carcasses to piles of splinters with their exceptionally powerful jaws. This combination of skills has allowed them to thrive in lands stalked by their Ice Age competitors. As Stéphanie Périquet and colleagues have found during a long-term study of hyenas in Zimbabwe’s Hwange National Park, when too many lions are around the hyenas simply change what’s on the menu.

The new study came out of observations of the park’s hyenas carried out between 1999 and 2013. And it was during the later part of this span, between 2005 and 2008, that lions made a minor comeback. A ban on lion trophy hunts around the park borders let the big cats proliferate and prowl the park in greater numbers than before, coming into greater competition with hyenas. You can see it in what the hyenas ate.

Over two study periods – one before and one during the lion surge – researchers followed groups of hyenas as they foraged and collected scat for analysis of the prey remnants inside. (The process for this latter effort involved soaking each turd in water and bleach for thirty minutes in a nylon stocking to extract the hairs inside, sun-drying those contents, and picking through them to match hair to prey species.) What the zoologists found didn’t match their expectations.

During the first period, when there were fewer lions, the hyenas focused on hunting mid-size and large prey like zebra, kudu, and buffalo, supplemented by smaller species. Périquet and coauthors thought that competition with lions would drive hyenas to focus on small prey. That way the hyenas could finish their meals before lions would have a chance to find them and steal the carcasses. Instead, however, the zoologists discovered that hyenas started traveling in mid-sized groups and started to avoid hunting zebra and kudu in favor of feasting on elephant and giraffe carcasses.

The strong jaws of spotted hyenas make them adept at both hunting and processing carcasses. Photo by Brian Switek.
The strong jaws of spotted hyenas make them adept at both hunting and processing carcasses. Photo by Brian Switek.

These changes were not in proportion to the availability of prey species. The number of giraffes actually declined between the two study periods, yet the hyenas were consuming giraffe more often. Lions may have been inadvertently supplying them. While the hyenas likely killed some of the giraffes, other times the carnivores acted as scavengers. This didn’t necessarily involve running the cats off their kills. Even when they pick a body “clean”, lions still leave a wealth of meaty morsels and marrow-filled bones on a carcass. All hyenas have to do is show up as a clean-up crew.

The scavenging shift may be attributable to the way hyenas hunt. Hyenas are pretty noisy when taking down prey, Périquet and colleagues note, and this makes it all the easier for lions to find them and snatch their kills away. By traveling in smaller groups and hunting less the Hwange National Park hyenas were able to go dark and avoid risking fights with enraged lions.

And the change worked. The hyena population, Périquet and coauthors note, remained stable even as lions moved in. Hyenas didn’t go from apex predators to dangling at the bottom of the food chain. Their magnificent jaws offered them another option, giving them plenty of reason to laugh at those pushy lions.


Périquet, S., Valeix, M., Claypole, J., Drouet-Hoguet, N., Salnicki, J., Mudimba, S., Revilla, E. Fritz, H. 2015. Spotted hyaenas switch their foraging strategy as a response to changes in intraguild interactions with lions. Journal of Zoology. doi: 10.1111/jzo.12275

Sabercats and Other Carnivores Kept the Ice Age World Green

A Smilodon angles to get a better bite on a sloth at the La Brea Tar Pits and Museum. Photo by Brian Switek.
A Smilodon angles to get a better bite on a sloth at the La Brea Tar Pits and Museum. Photo by Brian Switek.

The huge herbivores of the Ice Age were ecosystem engineers. Wherever they went, mastodons, sloths, bison, and their ilk changed the landscape by eating, defecating, trampling, and otherwise going about their plant-mashing business. But they were not isolated agents. Following out the engineer analogy, the megaherbivores of times past had managers. These were the sabercats, hyenas, wolves, and other predators past.

Many Pleistocene carnivores certainly look menacing enough. The long fangs of Smilodon have made it a staple of museum halls as well as schlock horror, and the thought of staring down a giant hyena is enough to send a shiver down my spine. So given that some prehistoric predators had such impressive weapons it’s not surprising that we’ve often imagined them setting into mammoths and other Ice Age giants. Bigger prey requires bigger cutlery, right?

Well, not quite. Many of the most iconic Ice Age herbivores were simply too big to kill. It’s the same reason why lions don’t chase after adult elephants. Clawing into a pachyderm is a high-risk scenario, even considering the fleshy reward, and fossil evidence has suggested the same pattern held in the Pleistocene. Smilodon didn’t take on adult mammoths and Megatherium, for example, but often targeted camels and bison instead. Large size was a refuge was most Pleistocene giants. But their offspring were a different story.

In a new study surveying the effects of large carnivores stalking the Ice Age landscape, University of California, Los Angeles paleontologist Blaire Van Valkenburgh and colleagues found that the young of many large Pleistocene herbivores would have been right in the sweet spot for hungry carnivores.

Part of the analysis involved sizing up the predators themselves. For starters, Van Valkenburgh and coauthors point out, not only were many extinct Pleistocene carnivores significantly larger than the predators that survived them, but each “carnivore guild” in the sample included a greater number of species in the past than comparable ecosystems today.

Even just looking at the felids, the researchers write, “nearly all Pleistocene predator guilds found outside of Australia included at least one and often two species of large sabertooth cat.” This pattern is directly related to the number of big herbivores there were to eat. Even in modern ecosystems, Van Valkenburgh and colleagues point out, the likelihood that three or more large carnivores might be present steadily increases. In addition to the herbivores creating more open habitat that give predators the opportunity to hide along the forested margins, there’s simply more meat to carve up.

Much of that flesh came in the form of juvenile giants. Even though we tend to think of adult specimens embodying any given fossil species, all prehistoric animals had to grow up. And just as with modern species – like the 74 juvenile elephants taken by lions over a four year period in Botswana – the little ones are vulnerable. Juveniles would have been even more at risk in the Ice Age, when apex predators were larger and there were far more of them.

Baby mastodon - like this one at the La Brea Tar Pits and Museum - would have been vulnerable until they reached about six years of age. Photo by Brian Switek.
Baby mastodon – like this one at the La Brea Tar Pits and Museum – would have been vulnerable until they reached about six years of age. Photo by Brian Switek.

Drawing from data on prey selection by modern carnivores, Van Valkenburgh and colleagues applied the same ecological arithmetic to the fossil record. While a solitary extant lion probably can’t capture even a two-year-old baby elephant, the paleontologists found, a lone Smilodon, Homotherium, cave lion, or other large cat would have been capable of hunting a baby mammoth or mastodon in the two-to-four-year-old range. (A sabercat den full of baby mastodon bones in Texas supports this contention.)  The chances of the Pleistocene predators only got better if they formed a pride, and social strategy was a boon to packs of wolves and clans of hyenas, too.

So while none of the Ice Age carnivores could have taken on an adult mammoth or mastodon, all of them – especially if they were social predators – were capable of tearing into the young. The big proboscideans would have been vulnerable until they were about six years old, which is a long time to have to be looking out for hungry eyes peering through the brush.

This is how the landscape was shaped by the subtle paw of the carnivores. Many paleontologists previously thought that Ice Age herbivores were too big to fail. That they existed at “saturation levels” because their size made them immune. But now Van Valkenburgh and coauthors have made a solid case that carnivores greatly influenced herbivore populations by preying on the young. This was violent, and even sad, but all a part of the constant ecological shuffle. Unchecked by carnivores, large herbivores can proliferate to destructive levels until they start eating themselves out of house and home. Smilodon, dire wolves, and other beasts of prey actually defended the plants – vegetation has no greater friend than a predator. That’s how large carnivores have been keeping the world green for millions of years , and I hope that our species can yield them the space to keep doing so.


Van Valkenburgh, B., Hayward, M., Ripple, W., Meloro, C., V. Roth. 2015. The impact of large terrestrial carnivores on Pleistocene ecosystems. PNAS. doi: 10.1073/pnas.1502554112


Life in the Slow(er) Lane: Revisiting the Long-Lost Giant Cheetah

For the most part, a cat is a cat is a cat. Large or small, domestic or wild, most are agile ambush predators that subsist almost entirely on meat. But then there’s the cheetah. It’s a cat that hunts like a dog. The felid’s claws are more like cleats than the retractable armaments of its relatives, its nasal cavity is enlarged to house the soft tissues necessary to keep it cool while sprinting, and, as the fastest land mammal, the cat relies on speed to chase down and trip up fleeing antelopes and gazelles. Cheetahs are so different, in fact, that figuring out when they adopted this speedy lifestyle has been clouded by the imagery invoked when we apply the term “cheetah” to their fossil relatives.

Take Miracinonyx, for example. The two species of this svelte fossil cat have often been called “American cheetahs” on the basis of their bones, and even inspired the idea that cheetahs first evolved in the New World rather than the Old. But this idea fell apart. Skeletal and genetic clues have shown that Miracinonyx was more closely related to cougars than cheetahs, and there’s some doubt about whether this cat rocketed over open ground after pronghorn or stalked steep rock walls and caves. The title of “American cheetah” invokes scenes of speed, but, even if the carnivore did so, this cat was a false cheetah.

Acinonyx pardinensis from France. From Geraads, 2014.
Acinonyx pardinensis from France. From Geraads, 2014.

The modern cheetah’s true fossil relatives started off in Africa about three million years ago and eventually dispersed through Eurasia before leaving only one species behind. But even though they were more closely related to today’s Acinonyx jubatus than other cats, the prehistoric forms didn’t live and hunt just like the living one. In fact, as Sorbonne University paleontologist Denis Geraads recently concluded, the cheetah as we know it today is a relatively recent evolutionary spinoff.

The focus of Geraads’ study was a skull of Acinonyx pardinensis found in France. This species ranged from Spain to Georgia about 2.4 million years ago, and previous paleontologists had concluded that the felid’s skull was already quite similar to that of the modern cheetah. Through using a technique called geometric morphometrics to compare the cat’s skull shape to that of other felids, however, Geraads found that Acinonyx pardinensis was not simply a big version of its living relative. The cat’s skull shape more closely resembled that of a cougar than the more specialized short, deep form of today’s cheetah. In short, the giant cheetah had a skull more like that of other pantherine cats, and the distinctive profile of the modern species evolved much more recently.

A comparison of a modern cheetah (a), Acinonyx pardinensis (b and c), and a jaguar (d). From Cherin et al., 2014.
A comparison of a modern cheetah (a), Acinonyx pardinensis (b and c), and a jaguar (d). From Cherin et al., 2014.

Two skulls and a jaw found in Italy bolster Geraads’ argument. Uncovered at a site in Pantalla, Italy and described by Perugia University paleontologist Marco Cherin and coauthors, these Aciononyx pardinensis skulls had some cheetah-like traits – such as a shorter relative length and enlarged nasal openings – but they also retained some traits of their ancestors, such as a high keel on the back of the skull for greater jaw muscle attachments. Acinonyx pardinensis was its own cat, with a skull intermediate in shape between today’s cheetah and its more cougar-like ancestors.

So what does this mean for how the extinct cheetah hunted? On the basis of muscle reconstructions threaded on CT scans of the Pantalla skulls, Cherin and colleagues tentatively suggest that the extinct cheetah had enough biting power to crush neck and skull bones like jaguars and cougars do. (Modern cheetahs, by contrast, often kill prey with a suffocating death grip on the throat.) More than that, Cherin and coauthors point out that Acinonyx pardinensis weighed about 176 pounds – twice as heavy as modern cheetahs – and that the relatively slender proportions of the cat’s postcrania cannot be immediately taken as evidence that it was a fast runner. The skeletons of snow leopards show some striking similarities to those of cheetahs, the researchers note, even though the two cats occupy very different habitats and hunt in very different ways. Despite its relationship to the modern cheetah, Acinonyx pardinensis was more like a typical big cat.

Restorations of Acinonyx pardinensis. Art by D.A. Iurino, from Cherin et al., 2014.
Restorations of Acinonyx pardinensis. Art by D.A. Iurino, from Cherin et al., 2014.

The term “cheetah” isn’t inaccurate for Acinonyx pardinensis. The fossil cat surely belonged to that lineage. But the title has also obscured how different this felid truly was. The exceptional nature of the modern cheetah has masked the unique nature of its fossil relatives. If we can remove that bias and understand fossil species in the context of their own time, we gain more than a richer understanding of the past. We earn a deeper appreciation for the vast changes that made our modern megafauna what they are.


Cherin, M., Iurino, D., Sardella, R., Rook, L. 2014. Acinonyx pardinensis (Carnivora, Felidae) from the Early Pleistocene of Pantalla (Italy): predatory behavior and ecological role of the giant Plio-Pleistocene cheetah. Quaternary Science Reviews. doi: 10.1016/j.quascirev.2014.01.004

Geraads, D. 2014. How old is the cheetah skull shape? The case of Acinonyx pardinensis (Mammalia, Felidae). Geobios. doi: 10.1016/j.geobios.2013.12.003

The Rise and Fall of America’s Fossil Dogs

When it came time to adopt a dog, I knew I wanted a dog. An angry, yappy gremlin wouldn’t do. I was on the lookout for a companion that at least somewhat resembled the gray wolf stock from which our domesticated canine companions descended. A real canid. Jet, a black German shepherd I took in earlier this summer, met that description perfectly.

But while I appreciate that Jet has a bit of ancient wolfishness about him, he’s not anything like the earliest dogs. Those dawn canids, which split from their cat cousins around 50 million years ago, were more weasel-like than any modern pooch. These were little ambush predators with dexterous forelimbs that let them grapple with prey. Wolves and other canids as we know them today – pursuit predators that use teeth, rather than paws, to catch and dispatch their victims – are relatively new creatures, and the last remaining sliver of what was once a wider array of prehistoric dogs.

A pair of papers published this month by two different teams of researchers tell the tale. The latest, published today by Universidad de Málaga‘s Borja Figueirido and colleagues, tracks how prehistoric dogs changed as forests gave way to grasslands.

Prior to 40 million years ago, much of North America would have be unrecognizable. Places that host prairies and deserts today were clothed in thick, humid forests where lemur-like primates and little, multi-toed horses browsed on soft leaves. By about 37 million years ago, though, these forests were ceding ground to grasslands.

Herbivores track the change. Some, like the forest-bound primates, went extinct, while the horses, rhinos, and other plant-chewers evolved higher-crowned molars better suited to grinding, grinding, grinding the tougher grasses. And while it was previously thought that this major ecological shift had relatively little effect on North America’s large carnivores, the new study by Figueirido and coauthors concludes that dogs actually went through some dramatic changes as grasslands carpeted the continent.

There were three major lineages of North American dogs during the past 40 million years. There were the early, weaselish hesperocyonines, the bone-crushing borophagines, and the more familiar, wolfish canines. And by looking at the elbow joints of species in all three groups, Figueirido and colleagues were able to reconstruct when canids evolved distinct hunting methods over time.

The hesperocyonines, for the most part, were ambush predators. They could easily turn their paws upwards and had arm flexibility similar to cats. But by around 27 million years ago, when grasslands had become widespread, the borophagines started doing something different. Their elbow joints, Figueirido and co-authors report, were more similar to “pounce-pursuit” predators – similar to modern foxes. Being able to run out in the open was becoming more important as the receding cover gave ambush predators less space to hide. And, speaking of the vulpine canids, the same pounce-pursuit method apparently evolved again around 7 million years ago around the last common ancestor of foxes and wolves. It wasn’t until the Pleistocene, around 2 million years ago, that the first full-on pursuit canids evolved. These dogs, including the predecessors of wolves, were endurance runners with elbows that primarily permitted a forward-back range of motion. As prey wandered out into the open, canids evolved into predators that could go the distance.

The skull of the small dog Archaeocyon pavidus compared to the large Epicyon haydeni. © AMNH/J. Tseng.
The skull of the small dog Archaeocyon pavidus compared to the large Epicyon haydeni. © AMNH/J. Tseng.

But dogs couldn’t stay on top forever. A second study, published earlier this month by University of Gothenburg paleontologist Daniele Silvestro and colleagues, found that competition between carnivores eventually drove two of the three dog lineages extinct.

Why some groups of organisms prosper and others are totally obliterated is the sort of mystery that keeps paleontologists up at night. Why, for example, were dinosaurs winnowed down to only the birds while mammals were better-able to resist the mass extinction of 66 million years ago and proliferate? This is still unknown. Yet, even if we can’t always get a handle on why balances tip this way or that, researchers can still track how rates of speciation and extinction have altered the course of life. The record of North America’s dogs offered one such opportunity.

In addition to the hesperocyonines, borophagines, and canines, Silvestro and coauthors investigated the speciation and extinction records for cats, nimravids (false sabercats), barbourofelids (another false sabercat lineage), amphicyonids (bear dogs), and bears over the last 40 million years. All of these included large carnivores that jostled for space and prey with the canids. By looking at how these different groups fared, the paleontologists picked up patterns that can be explained by groups outdoing each other.

Some of the competition was between the dogs. Between 20 and 10 million years ago, for example, the archaic hesperocyonines suffered a high extinction rate just as the borophagine dogs were undergoing an expansion in their range of body sizes. They were infiltrating the predatory niche the hesperocyonines had controlled for millions of years. This, Silvestro and coauthors write, is a sign of what’s called active displacement – one lineage shouldering out another. The telltale clue is that once the more archaic dogs were gone, the borophagines didn’t undergo a major radiation (as would be expected if they were somehow being suppressed under “passive displacement” by their competition).

But the borophagines eventually went extinct, too, and competition with a wider array of predators may be the reason why. The borophagines had an intermediate, pounce-pursuit joint structure and many were hypercarnivorous, subsisting almost wholly on flesh and bone. This put them in direct competition with the more dexterous cats who jumped from the tall grass as well as the marathon-running canines. Borogphagines may have wound up in the middle of two guilds of predators that had specialized on the ambush and pursuit modes of taking down prey, respectively, leaving the borophagines in the generalist valley between them. Their extinction rate outpaced the rate at which they spun off new species, leaving the running to the canines and the stalking to the felids. Think about that the next time you throw a ball for your puppy or dangle a toy mouse in front of your housecat. The way they play – which is itself predatory practice – is a faint, compact glimmer of 40 million years of extinction and evolution.


Figueirido, B., Martin-Serra, A., Tseng, Z., Janis, C. 2015. Habitat changes and changing predatory habits in North American fossil canids. Nature Communications. doi: 10.1038/ncomms8976

Silvestro, D., Antonelli, A., Salamin, N., Quental, T. 2015. The role of clade competition in the diversification of North American canids. PNAS. doi: 10.1073/pnas.1502803112

Saberkittens Were Double-Fanged for 11 Months

The La Brea asphalt seeps have me trapped. It seems I can’t visit Los Angeles without stopping by the Ice Age treasure trove to pester the paleontologists at Project 23 about what they’re finding and wander among the chocolate-colored skeletons inside the Page Museum. And in those halls, there’s one exhibit that never ceases to amaze me. Lined up behind glass are Smilodon skulls with two sets of fangs.

It’s actually not surprising that young sabercats temporarily carried two sets of upper canines. If you’ve ever raised a kitten, you may have noticed when their permanent teeth started to erupt and push their milk teeth out of the way. That’s a standard mammalian feature, as true for Smilodon as your household moggie. But juvenile Smilodon were a bit different. They were double-fanged for nearly a year.

The new numbers come from the latest paper on Smilodon tooth growth. Building on previous work by University of California paleontologist Robert Feranec, the study by M. Aleksander Wysocki, Feranec, and coauthors used a combination of geochemical traces, micro CT scans, and growth data from living carnivores to come up with absolute ages for major events in the early years of La Brea’s Smilodon cubs.

Little Smilodon started to grow their teeth while still in the womb. Wysocki and colleagues calculate that the felid’s teeth started to develop about a month before birth and those little grippers, slashers, and slicers grew at about 6 millimeters a month (close to Feranec’s earlier estimate of 5.8 millimeters a month). At this rate, Smilodon cubs had almost all their milk teeth by 4 to 7 months old, with their temporary baby sabers fully in place between 11.5 and 18 months.

Young Smilodon had their milk and permanent canines for about 11 months. Photo by Brian Switek
Young Smilodon had their milk and permanent canines for about 11 months. Photo by Brian Switek

But the permanent, characteristic, killing canines of Smilodon didn’t simply push the milk versions out. They came in alongside, and, according to the new study, the young sabercats were in the awkward position of having milk canines and still-growing adult sabers for about 11 months. This could’ve been a simple byproduct of growth. The adult canines required about 22 months to fully erupt, putting Smilodon at around three years old by the time their teeth had finally settled. Then again, Wysocki and colleagues write, perhaps this arrangement had a functional advantage. Maybe the milk teeth helped shield the flattened and relatively fragile adult sabers as they came into place.

The overall picture is that Smilodon upper canines erupted at a faster rate than those of lions, tigers, and other modern cats, but, by dint of the sabers’ size, that the process took a much longer time. This might provide some clues to how the sabercats grew up. Smilodon kittens younger than seven months may have required more attentive care from their mothers and stayed near their dens, which could explain why these earliest days of Smilodon life are totally unknown from La Brea. And depending on how effectively young Smilodon could have caught and dismantled prey while their adult canines were coming in, the findings could throw indirect support to the idea that these sabercats were highly social carnivores that relied on pride life while young.

As much as I’m tickled by the thought of awkward, double-fanged Smilodon youngsters, though, this new study has some serious implications for reconstructing past life. If paleontologists can determine when a certain skeletal part—like a tooth—starts growing and accurately measure the rate at which that feature grew, Wysocki and co-authors suggest, then they can pin absolute dates on developmental milestones in the life of that animal. For example, the new study was able to assign dates to when certain Smilodon skull bones fused because those events occurred during the span of time when the adult canines were growing. The same technique could be applied to other animals with long-growing teeth, such as mastodons and narwhals, to piece together a more precise view of how they changed with age. If you really want to understand the day-to-day life of extinct animals, it’s wise to look them in the mouth.


Wysocki, M., Feranec, R., Tseng, Z., Bjornsson, C. 2015. Using a novel absolute ontogenetic age determination technique to calculate the timing of tooth eruption in the saber-toothed cat, Smilodon fatalis. PLOS ONE. doi: 10.1371/journal.pone.0129847

How Cougars Survived the Ice Age

Extinction can make animals seem stranger than they really are. Consider woolly mammoths. The last of these Ice Age beasts died out about 4,000 years ago, which really does seem like ancient history when compared to the span of a single life. Yet the reality is that 4,000 years is only a bare sliver of geologic time, and if mammoths had survived to the present day they probably wouldn’t seem all that unusual or out of place. After all, that’s how we treat the Ice Age survivors that continue to thrive around us.

The reasons mammoths, sabercats, short-faced bears, and other Pleistocene megafauna went extinct is a puzzle that has spawned a surge of scientific papers over the past century. Why other creatures survived through the same extinction pulse has received comparatively little attention. Coyotes, for example, loped around the La Brea asphalt seeps at the same time as Smilodon and still inhabit Hollywood. Cougars are Ice Age survivors, too. They prowled the same landscapes as sabercats and American lions, and, with a range from Canada to almost the southern tip of South America, are among the world’s most successful big cats. Why did pumas prosper while their hypercarnivorous kin slipped away?

Cougars lived at La Brea, alongside dire wolves, Smilodon, and other Ice Age megafauna. Art by Robert Bruce Horsfall, from A History of Land Mammals in the Western Hemisphere.
Cougars lived at La Brea, alongside dire wolves, Smilodon, and other Ice Age megafauna. Art by Robert Bruce Horsfall, from A History of Land Mammals in the Western Hemisphere.

Paleontologists Larisa DeSantis and Ryan Haupt think diet made all the difference.

Looking at the microscopic scratches and dents on the teeth of cougars, Smilodon, and American lions that became entombed in the muck of La Brea over 12,000 years ago, the researchers found that the wear patterns on the ancient cougar teeth most closely matched those of modern African lions. This suggests that, like lions, cougars not only ate flesh, but also gnawed bones and chewed through tougher-skinned prey that other predators ignored. The different patterns of damage of Smilodon and American lion teeth, by contrast, suggests more specialized soft tissue diets for these lost carnivores.

Much like their living representatives, Ice Age cougars caught and scavenged a variety of prey. (A dried cougar scat I saw in Argentina a few weeks ago contained armadillo armor and articulated raptor claws, along with tufts of hair from furrier meals.) This may have given cougars an edge in the long run. They may not have been slaughtering bison, camels, or baby mammoths like the other cats of their time, but cougars were experts at breaking down carcasses. This allowed them to persist through gluts and famines alike. And if paleontologists can get a clearer picture of what allowed cougars, coyotes, and other Ice Age species to survive, maybe we can better understand the weaknesses that stripped the world of the megafauna we miss so much.


DeSantis, L., Haupt, R. 2014. Cougars’ key to survival through the Late Pleistocene extinction: insights from dental microwear texture analysis. Biology Letters. 10: 20140203

How Leopards Helped Make the Fossil Record

I have to apologize to carnivores. In an article about how to become a fossil, published last summer, I wrote that I wasn’t enamored with the idea of being deposited in the fossil record as bone scraps in carnivore dung. That’s still true, but I should have done more than make a passing joke about my fossilization preferences. There’s more to the story than scat. Carnivores have contributed greatly to literally assembling the fossil record.

From crocs to hyenas, predatory animals past have inadvertently assisted paleontologists by bringing their meals to lake bottoms, caves, and other places amenable to preservation. Worse for wear the skeletons they may be, but it’s better to have bitten bones than none at all. And among all these carnivorous accumulators, leopards have been especially helpful.

Watch any nature documentary about big cats and you’re likely to see a guarding a kill the cat has stashed up a tree. Prehistoric leopards likely did the same, but they also dragged carcasses back to caves. Lairs replete with bones are cat-created records of prehistoric fauna, including early humans, and one such Ice Age site in northeastern Spain is the focus of a new PLoS One paper by paleontologist Víctor Sauqué and colleagues.

Known as Los Rincones, the cave contains a Pleistocene mix of mammals that lived in the area prior to 12,000 years ago. From 1,443 collected fossils, the researchers counted brown bear, wolf, leopard, lynx, red deer, roe deer, Spanish ibex, Pyrenean chamois, a large bovid, and two horse species among the large mammals. From the details of those bones – including the ages of the animals that deposited them to the pattern of remains preserved – Sauqué and coauthors concluded that leopards were the primary agents creating the assemblage. To do that, though, they had to navigate some tricky aspects of the boneyard.

A breakdown of identified large mammal elements at Los Rincones. From Sauqué et al., 2014.
A breakdown of identified large mammal elements at Los Rincones. From Sauqué et al., 2014.

Looking at the representation of animal remains found in Los Rincones, brown bears might initially seem to be the most important carnivores. Their skeletons are far more complete and significantly more numerous than those of leopards, embodying a range of ages from cubs to adults. But rather than representing a predatory presence, Sauqué and colleagues argue, these aspects of the bear bones indicate that the ursids were hibernating in the cave. Maybe they chewed on bones already there, but, since bears aren’t known to take food back to lairs, their numerous bones mean that they used Los Rincones as a spot to snooze more than anything else.

A few of the cave’s bones also bear cutmarks made by humans. Was the cave a slaughterhouse used by prehistoric people? Unlikely. The cut marks and remnants of stone tools are few, and there’s no sign of sustained human presence. People may have used the cave to butcher kills on occasion, Sauqué and coauthors suggest, or the bones could have been scavenged by carnivores after humans had taken their share from carcasses. If humans stopped by the cave at all, they didn’t stay.

Given that the cave’s bones looked to be accumulated by animals, rather than washed in from the outside, this left Sauqué and colleagues with two candidates – hyenas and leopards.

Hyenas are bone hoarders, and also roamed across Spain during the last Ice Age. But they probably had little, if anything, to do with Los Rincones. For one thing, no sign of hyenas has been found in the cave so far. No scat, no bones chawed in a hyena-like fashion, no milk teeth from the pups they would have raised there. Not to mention that hyenas often tear off pieces of larger mammals to run back to their dens. A hyena-created cave assemblage would have elements from mammoths and other big beasts, which are lacking at Los Rincones.

Leopard bones found in Los Rincones. From Sauqué et al., 2014.
Leopard bones found in Los Rincones. From Sauqué et al., 2014.

Leopards are a better bet. Not only are they the second most common carnivore at the site – their bones making up a little more than 12% of the recognized fossils – but the details of the rest of the assemblage fit their modus operandi. The majority of the herbivorous animals found in the cave are juveniles of mid-sized herbivores such as the especially-prevalent Spanish ibex. These horned herbivores fit within the preferred prey range seen among leopards alive today – big enough for a good meal, but not so big as to be impossible to haul away to a secretive spot. More than that, leopards left the skeletons of the carcasses much more intact than hyenas would. Cats mainly feed on soft tissues with hyenas are capable of crunching bones down to shards.

Based on the fossil trail the cats left behind, it seems that the leopards pounced on unwary ungulates that grazed and browsed near the cave. Rather than dismember their prizes at the scene, though, the spotted felids dragged their kills back to the cave to eat in relative safety, littering the lair with skeletal leftovers. The cats didn’t stay there permanently – brown bears and humans left their mark on the assemblage as they took their turns in Los Rincones – but leopards were responsible for hoarding most of the fossil riches paleontologists now pick over. Thanks, cats.


Sauqué, V., Rabal-Garcés, R., Sola-Almagro, C., Cuenca-Bescós, G. 2014. Bone accumulation by leopards in the Late Pleistocene in the Moncayo Massif (Zaragoza, NE Spain). PLoS ONE. 9, 3: e92144. doi:10.1371/journal.pone.0092144

How Saberkittens Got Their Fangs

Smilodon fatalis – one of the last great sabercats – was a ferocious carnivore. Gaping museum mounts are a reminder of the extinct cat’s destructive capabilities. But such menacing skeletons only offer a snapshot of predator’s life. It’s not as if Smilodon sprung from the ground fully-formed and started tearing after the nearest baby mammoth. If there were sabercats, there must have been saberkittens.

When I visited the famous La Brea asphalt seeps last year for a Smilodon story, I asked curator John Harris and collections manager Aisling Farrell if they had any young sabercats in the rows upon rows of chocolate-colored bone collected from the site. They led me to a specific tray among the racks of immaculately-cleaned Smilodon bones and, sure enough, there were skull pieces from several juvenile cats nestled against the plastic.

It was heartbreaking to think of the unwary saberkittens becoming trapped in the black ooze. If I happened across such a scene I would rush to pick up the cats, end up trapped in the tar myself, and, following anthropological convention, be named “Cat Man” when paleontologists later discovered the associated skeletons. But although the thought of helpless, tar-matted Smilodon kittens is tragic, their bones have not gone to waste. Their rare remains, and those of their older kin, are helping paleontologists understand how roly-poly Smilodon infants grew up into intimidating throat-rippers.

Like all cats, Smilodon got through life with two sets of teeth. Their first dental armaments were milk teeth, including canines that were not quite so long as their parents’ but were still flattened and saber-like. And much like kittens you may have raised yourself, little Smilodon kept their milk teeth until their adult teeth pushed the old ones out of the way. Skulls of this transition in action show the sabercat’s awkward, double-fanged teething phase.

A young Smilodon with the adult canine pushing past its milk tooth. Photo by Brian Switek.
A young Smilodon with the adult canine pushing past its milk tooth. Photo by Brian Switek.

Those adult fangs came in quick. In a pair of papers, University of California paleontologist Robert Feranec looked to the teeth of adult La Brea Smilodon to estimate the growth of the famous weapons. By tracking fluctuations of carbon and oxygen isotopes, which were laid down in the enamel of the two sampled Smilodon canines as they formed, Feranec determined that those distinctive, permanent slashers grew at a rate of about 5.8mm each month over a period of 22 months. In the same amount of time it takes modern lions to grow their adult canines, Smilodon sprouted insanely-long slashers.

Despite the high rate of growth, though, 22 months was a long time for a Smilodon to be without its fully-developed cutlery. The saber teeth would have been functional before they ceased growing, of course, but many months of early growth – when their grown-up canines were pushing aside their milk fangs bit-by-bit – likely kept young Smilodon cute for a long time. An extended period of infancy and weaning, megafauna expert Ross Barnett pointed out on Twitter, might mean that saberkittens stayed adorable and playful for longer than other cats. Science has yet to ascertain how dangerous it would have been to give saberkittens chin scritches, however.

[A big hat-tip to paleontologist Ross Barnett for pointing me to Feranec’s papers.]

Related Reads:

Tracing the Roots of Smilodon
A Living Sabertooth
The Many Lives of Smilodon
Smilodon the Vampire
Q: How Do You Sex a Smilodon? A: Very Carefully


Feranec, R. 2004. Isotopic evidence of saber-tooth development, growth rate, and diet from the adult canine of Smilodon fatalis from Rancho La Brea. Palaeogeography, Palaeoclimatology, Palaeoecology. 206, (3-4): 303-310

Feranec, R. 2008. Growth differences in the saber-tooth of three felid species. PALAIOS. 23: 566-569

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Sneaky Spotted Cat Has Been Disguised As Another Species

Cats are known for being elusive and stealthy, but the southern tigrina takes those qualities to a new level. For decades, this South American feline has been hiding in plain sight, mistaken for a close relative called the tigrina or oncilla.

Physically, the two species are almost indistinguishable—both look like domestic cats with leopard-like spots. There southern tigrina is slightly darker than its north-eastern cousin, its spots are slightly larger, its tail is slightly shorter, and its ears are slightly rounder. But there’s more physical variation within each species than between them.

It’s their DNA that reveals the gulf between them. By analysing the genes of 115 “tigrinas” from all over Brazil, Tatiane Trigo showed those in the north-east are genetically distinct from those in the south and south-east, and the genetic differences between them are as large as those between other cat species. Although both tigrinas are found in central Brazil, some unknown barrier stops them from mating and they have not bred for some time.

Thanks to its genes, a second tigrina species has blinked into view, like a reverse Cheshire cat.

Trigo is assigning the classic name—tigrina (Leopardus tigrinus)—to the  north-eastern cats, and she has named the others southern tigrinas (Leopardus guttulus).

These felines are the latest examples of cryptic species, where a single animal actually turns out to be two or more, largely thanks to genetic studies. There are two species of African elephants, two Nile crocodiles, and possibly many species of killer whales and giraffes.

Things get even more complicated when you consider two other small cats that live in South America. Geoffroy’s cat (Leopardus geoffroyi) is larger and stockier than the tigrinas, and its spots are solid dots rather than open rosettes. The pampas cat (Leopardus colocolo) is even more distinctive—it has stripes on its legs, pointed ears, and a shorter tail.

Geoffroy's cat. Credit: Charles Barilleaux.
Geoffroy’s cat. Credit: Charles Barilleaux.

Trigo showed that some of the genes in the tigrinas (but not the southern ones) came from the pampas cats. Although the two species don’t mate any more, they must have hybridised at some point in their history. This may have been important for the tigrinas. Unlike their forest-dwelling southern cousins, they live in open plains… and so do the pampas cats. Maybe they gained important adaptations for life in the open after their ancestors bred with plains specialists. “This is an intriguing possibility in this case, and we plan to further investigate it,” says Trigo.

The team also found that Geoffroy’s cat is still hybridising with the southern tigrinas! Southern Brazil, where the two species overlap, is effectively a “hybrid swarm”—a zone where almost all southern tigrinas and Geoffroy’s cats are partial hybrids of the two.

So, do they still count as separate species? Trigo thinks so. Their genes tell a story of separation and reunion. The two cats did properly split off from each other some time ago. But after the last Ice Age, the southern tigrinas experienced a population boom, and started expanding into southern Brazil where they met up with their long-separated Geoffroy’s cat cousins. They bred, and their offspring are clearly fertile. But there are still strong genetic differences between the two cats in parts of their range outside the contact zone. They’re not going to merge back into a single species.

Trigo’s priority now is to find out more about the north-eastern tigrinas, which have been poorly studied compared to their southern kin. How does it live? How many are there? Is it in need of protection? There are still many secrets to be learned from biodiversity, including cryptic species in groups that are thought to be well-known, such as wild cats,” she says.

The team are now planning to study other South American cats, like the ocelot and margay. They’ve already found some interesting genetic divisions within both species throughout their range, although nothing definitive yet. On the flipside, they’ve found some evidence that the pampas cat is not, as others have suggested, two or three distinct species.

Reference: Trigo, Schneider, Oliveira, Lehugeur, Silveira, Freitas & Eizirik. 2013. Molecular Data Reveal Complex Hybridization and a Cryptic Species of Neotropical Wild Cat. Current Biology

More on hybrids and cryptic species:

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Photo Safari – Serval

On our recent trip to South Africa, we saw all of the big cats – lions, cheetahs and leopards. But it was the serval that really captivated me, not least because never expected to see one. It’s long, slender legs allow it to leap metres into the air, and sometimes catch flying birds. It can just as easily direct the pounce downwards to snag rodents that it detects with those large ears. Which is exactly what the one we saw did.

It took a couple of minutes to finish its meal and lick itself clean, and then it was off stalking again.


Claw Cuts and Postmortem Paleo Clues

“A tiger enrichment program was used to document actual bone damage unequivocally caused by claws.” As soon as I read that line in the abstract of this new study, I was hooked. An image hovering over the abstract pulled me in further. Embedded inside a piece of wood is a piece of bone. Reads the caption, “Figure 1. Bovid femur bolted in log, accessible to paws, but not jaws.” All this in the name of paleontology.

Fossil bones are rarely found pristine and intact. In the early days of their afterlives, bones can be burrowed into by insects, tumbled along stream beds, trampled, and otherwise come to bear the marks of postmortem history under the banner of what researchers call “bone modifications.” Sifting through these clues is part of the science of taphonomy – reconstructing how an organism died and what happened afterwards – and among the common clues that paleontologists regularly puzzle over are gouges, scrapes, and pits that seem to record bite marks. But when is such damage a clue of a prehistoric bite and when is it an indicator of scraping claws? This question is what led paleopathologist Bruce Rothschild and coauthors to devise bony toys for tigers.

Cow bone bolted into a log for the claw damage experiment. Image from  Rothschild et al., 2013.
Cow bone bolted into a log for the claw damage experiment. Image from Rothschild et al., 2013.

After carefully removing flesh from cow femora – thigh bones – so as not to damage the thin, surrounding membrane called the periosteum, researchers bolted one bone at a time inside a piece of wood. This allowed the tiger at Wichita, Kansas’ Sedgwick County Zoo to reach inside and paw the bone, but not mouth the scientific plaything. True to feline nature, the big cat was quite curious about the object. “The tiger expressed major interest in the object, pawing at the bone in the log,” Rothschild and colleagues write, “but was unable remove it from its bolted location.”

The tiger’s claws scratched the bone in at least four places. Each shallow rut created by the tiger “appeared marred and lacked periosteal covering compared to unscratched (control) regions” of the bone, the researchers report. Microscopic examination confirmed that the tiger’s claws punched through the outer periosteum to leave shallow scratches on the actual bone beneath.

Despite being composed of a material softer than bone, the tiger’s claws were able to slightly damage the cow femur. That’s a simple finding, but one that suggests that paleontologists should be on the lookout for claw scratches as they pore over fossil bones.

Frustratingly, however, the PLoS One study doesn’t go beyond a simple experiment to demonstrate that claws can damage bone tissue. The authors provide no details about the tiger’s behavior during the time the scratches were created, nor do they attempt to categorize what might separate a prehistoric claw mark from a bite wound or other damage. Likewise, I’m quite curious to know how claw scrapes created by tigers differ from those left by other cats, birds of prey, and other clawed vertebrates, as well as how scratches created by pawing differ from claw damage on bones that big cats grasp and gnaw. Documenting that claws can scratch skeletons is only a bare bones beginning to a thread of interrogation that may help us better understand the postmortem fates of creatures that perished so very long ago.


Rothschild, B. Bryant, B., Hubbard, C., Tuxhorn, K., Kilgore, G., et al. 2013. The power of the claw. PLoS ONE 8, 9: e73811. doi:10.1371/journal.pone.0073811

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It’s a Myth That Cheetahs Overheat While Hunting

In 1973, two Harvard scientists bought a couple of hand-reared cheetahs from an African farmer, flew the animals over to their laboratory, made them run on treadmills, and stuck thermometers up their bums. Based on the readings, they concluded that cheetahs can’t lose heat quickly enough while running. Once their body temperature hits 40.5 degrees Celsius, they’re forced to stop.

It was a groundbreaking experiment, but an incredibly artificial one. The cheetahs had lived in captivity for their entire lives, and they were running in a lab rather than a savannah. They ran at 30 kilometres per hour for 2 kilometres whereas, in the wild, they sprint for just a few hundred metres but at speeds of up to 100 km per hour.

And yet, based on this single contrived set-up, it became common knowledge that cheetahs abandon hunts because they overheat. You’ll find that little factoid in zoo placards, books, and wildlife documentaries. It seems plausible, especially since cheetahs are the world’s fastest land animals. They’re also relatively inefficient hunters that only kill 40 percent of the prey they chase. In some cases, they seem to give up even when their quarry is within range. Is that because they get too hot? Sure. Why not? It has the ring of truth.

It’s not true.

Robyn Hetem from the University of Witwatersrand in South Africa has disproved this myth by actually studying wild hunting cheetahs. She worked with six animals from the Tusk Trust Cheetah Rehabiliation Park, which allows orphaned or injured animals to hone their hunting skills before returning to the wild. Her team surgically implanted two sensors into each cheetah—one in their hips to track their movements, and another in their bellies to track their temperature. For seven months, the cheetahs did their thing and Hetem watched.

Her data showed that their body temperature naturally fluctuates between 37.3 and 39.5°C over the course of a day, and hunting doesn’t change that. Despite their enormous speed and acceleration, they barely get any hotter while sprinting. And while they finished successful hunts with an average body temperature of 38.4°C, they finished unsuccessful ones at… 38.3°C. That’s a definition of “overheating” that I’m unfamiliar with.

Clearly, cheetahs don’t give up because of heat. They do, however, heat up more if they actually catch something. In the 40 minutes after they stopped, their temperature rose by 0.5°C if they had flubbed their chases, but by 1.3°C if they made a kill.

This wasn’t due to the ambient temperature, the length of the chase, or how fast the cheetahs ran. It wasn’t due to the act of killing, since that only takes 10 minutes. It wasn’t due to energetic eating either, since cheetahs take long rests before tucking into their prey.

Instead, Hetem thinks it’s a sign of stress. Cheetahs are built for speed not strength, and they can be easily overpowered by other plains predators like lions, hyenas or leopards. Indeed, a leopard actually killed two of the six cheetahs that Hetem was studying! This means that a freshly killed carcass could attract deadly competitors, as well as providing a meal, which is why other biologists have described cheetahs as being “nervous at kills” and “alert when feeding”. Hetem thinks that their temperatures rise as a result.

Of course, none of this explains why cheetahs abandon chases early. Perhaps Alan Wilson’s work might eventually provide an answer, using the astonishing collars he developed to track the movements of wild cheetahs. These same collars helped to check another cheetah factoid—the idea that they can actually hit top speeds of 100 km per hour. That was also based on a single artificial study, but to the relief of cheetah fans everywhere, it turned out to be right. Wild cheetahs do actually get very close to that speed when they hunt.

I’ve been fascinated recently by how much of our natural history consists of similar barely-substantiated claims that have only been recently tested. Some turn out to be true, like the cheetah’s speed or the function of the thresher shark’s tail. Others are myths, like the cheetah’s heat problems, or the komodo dragon’s bacterial bite (they use venom), or the honey badger’s partnership with honey guides (deceitful documentary-makers), or the suicidal tendencies of lemmings (deceitful film-makers). One wonders what other myths will be busted in coming years.

Reference: Hetem, Mitchell, de Witt, Fick, Meyer, Maloney & Fuller. 2013. Cheetah do not abandon hunts because they overheat. Biology Letters

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Collars Reveal Just How Extreme Cheetahs Can Be

In Botswana, a cheetah explodes into action, and so does its collar. Within seconds, it hits a top speed of 59 miles per hour, driven by leg muscles that generate more power than those of any other runner. Awakened by this phenomenal acceleration, the sensors around its neck record its position and movements, from its first footfalls to the death of its impala prey.

Using these collars, Alan Wilson from the Royal Veterinary College has shown just how extreme a wild cheetah’s movements can be. It’s the culmination of his long-running fascination with an animal that combines two of his great loves—veterinary science and track athletics. “If you’re interesting in running, you very quickly develop an interest in what the cheetah does,” he says.

The cheetah is the world’s fastest land creature, and exists at the very limits of what an animal’s body can accomplish. We know a lot about the adaptations that make them so fast. For example, its flexible spine allows its shoulders and hips to swing through large arcs, greatly extending the length of its stride. In this mind-blowing National Geographic video, watch any foot leaving the ground, and note just how far the cheetah travels before that foot lands again.

But just how fast are they? The published top speed is 64 miles per hour (29 metres per second), which is considerably faster than greyhounds (40 mph), racehorses (42 mph) or Usain Bolt (28 mph). But that figure was based on a single measurement taken in the 1960s. Whenever Wilson clocked captive cheetahs chasing lures on strings, they only performed at greyhound level. “Most of these animals have been reared in a zoo for many generations and have never run for their dinner,” he says. “They’re resting on their evolutionary laurels.”

To really understand what these cats can accomplish, Wilson wanted to study wild ones. He flew to northern Botswana, where a local charity had been studying five cheetahs using tracking collars. Wilson replaced these with new ones of his own design, which could record the animals’ position and acceleration, and were programmed to record more data if the animals were moving quickly. “I’m very proud of the design,” says Wilson. “We made all the hardware and software ourselves.”

“It took substantial imagination to realize how these technologies could be used to investigate these elusive mammals,” says John Bertram at the University of Calgary. “Cheetahs are only highly active for very brief periods, so they’re extremely difficult to observe any other way.”

The data from the collars is astonishing, not least when Wilson overlays it onto maps of the terrain captured through Google Earth. In one hunt, he can see one of the cheetahs using a termite mound to bank! He could even distinguish between runs when cheetahs killed their quarry and those when the prey got away.

Collared cheetah. Credit: Alan Wilson, RVC.
Collared cheetah. Credit: Alan Wilson, RVC.

Wilson recorded a total of 367 runs, of which a quarter ended in a kill. There were many surprises. Wildlife documentaries typically show these cats hunting during the day in open grassland. But Wilson’s individuals were hunting day and night. They also made half their runs among shrubs or thick vegetation, and were actually more successful in thicker cover.

The collars cemented the cats’ speedy reputation. The fastest individual, appropriately named Ferrari, hit a top speed of 59 mph, very close to the reported 64 mph maximum. And while that old measurement was taken on a flat, track-like surface, Ferrari was running through vegetation.

But most of the time, the cheetahs didn’t run as fast as they could. Across their hunts, their average top speed was just 33 mph (15 metres per second) and they only hit that for one or two seconds. That’s because speed isn’t the critical factor in a hunt—when the cheetahs killed their prey, they weren’t running any faster than when they flubbed their hunts.

It’s manoeuvrability that matters. To hunt agile prey like impala, cheetahs have to dodge and weave, which becomes much harder at full pelt. Just think about how much harder it is to turn a car at 60 mph than at 20 mph. “If you want to catch something, you don’t want to go faster than you have to,” says Wilson. “Manoeuvring becomes harder if you go quickly.” So, perhaps counter-intuitively, the ability to slow down sharply before a turn is incredibly important.

Cheetahs accomplish this with leg and back muscles that make up half its body weight. These contract at such high speeds that each kilogram of muscle generates 100 watts of power. For comparison, greyhounds produce just 60 watts with the same amount of muscle, horses manage just 30 watts, and Usain Bolt can produce just 25. With these powerful muscles, a cheetah can speed up or slow down by up to 9 mph in a single stride. The cat is like a sports car that always runs on second gear.

The importance of turning also helps to explain some bizarre aspects of the cheetah’s anatomy. People often assume that its limbs should be light and slender so they can move quickly through the air. “However, cheetah limbs are actually quite massive for the animal’s body weight,” says Bertram. “[Wilson’s study] indicates that the extreme forces borne by the skeleton, in manoeuvres such as braking, require a reinforced skeleton.”

Wilson now has bigger plans for his collars. He wants to study other populations of cheetahs, including those that hunt in packs (the collars can be programmed to turn each other on if they sense a hunt has started). The latest collars can also relay their position to cameras on overhead planes, allowing Wilson to film hunts from above.

He has also started to collar other predators, like wild dogs, leopards, lions… and domestic cats. In The Secret Life of the Cat, a documentary airing on BBC2 tomorrow, Wilson’s collars were fixed onto 50 cats in Surrey, England to see what they do when they exit their cat-flaps.

Reference: Wilson, Lowe, Roskilly, Hudson, Golabek & McNutt. 2013. Locomotion dynamics of hunting in wild cheetahs. Nature

More: Cheetahs do not prosper. Fewer than 10,000 of them survive in the wild, and you can read about their plight in this excellent National Geographic feature.