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Research News at Vanderbilt

Evidence shows starvation did not cause saber-tooth cat extinction

by | Posted on Wednesday, Dec. 26, 2012 — 4:00 PM

Saber-tooth cats attacking a bison. (Copyright Mauricio Anton)

In the period just before they went extinct, the American lions and saber-toothed cats that roamed North America in the late Pleistocene were living well off the fat of the land.

Saber-toothed tiger exhibited at the Page Museum at the La Brea Tar Pits in Los Angeles. (Courtesy of Larisa DeSantis / Vanderbilt University)

That is the conclusion of the latest study of the microscopic wear patterns on the teeth of these great cats recovered from the La Brea tar pits in southern California. Contrary to previous studies, the analysis did not find any indications that the giant carnivores were having increased trouble finding prey in the period before they went extinct 12,000 years ago.

The results, published on Dec. 26 in the scientific journal PLOS ONE, contradicts previous dental studies and presents a problem for the most popular explanations for the Megafaunal (or Quaternary) extinction when the great cats, mammoths and a number of the largest mammals that existed around the world disappeared.

Larisa DeSantis making impressions of saber-tooth cat teeth at the Page Museum at the La Brea Tar Pits. (Courtesy of Larisa DeSantis / Vanderbilt University)

“The popular theory for the Megafaunal extinction is that either the changing climate at the end of the last Ice Age or human activity – or some combination of the two – killed off most of the large mammals,” said Larisa DeSantis, assistant professor of earth and environmental sciences at Vanderbilt, who headed the study. “In the case of the great cats, we expect that it would have been increasingly difficult for them to find prey, especially if had to compete with humans. We know that when food becomes scarce, carnivores like the great cats tend to consume more of the carcasses they kill. If they spent more time chomping on bones, it should cause detectable changes in the wear patterns on their teeth.”

In 1993, Blaire Van Valkenburgh at UCLA published a paper on tooth breakage in large carnivores in the late Pleistocene. Analyzing teeth of American lions, saber-tooth cats, dire wolves and coyotes from La Brea, she found that they had approximately three times the number of broken teeth of contemporary predators and concluded, “…these findings suggest that these species utilized carcasses more fully and likely competed more intensely for food than present-day large carnivores.”

The latest study uses a new technique, called dental microwear texture analysis (DMTA), developed by co-author Peter Ungar at the University of Arkansas. It uses a confocal microscope to produce a three-dimensional image of the surface of a tooth. The image is then analyzed for microscopic wear patterns. Chowing down on red meat produces small parallel scratches. Chomping on bones adds larger, deeper pits. Previous methods of dental wear analysis relied on researchers to identify and count these different types of features. DMTA relies on automated software and is considered more accurate because it reduces the possibility of observer bias.

DeSantis and Ungar, with the assistance of Blaine Schubert from East Tennessee State University and Jessica Scott from the University of Arkansas, applied DMTA to the fossil teeth of 15 American lions (Panthera atrox) and 15 saber-tooth cats (Smilodon fatalis) recovered from the La Brea tar pits in Los Angeles.

In order to study the microscopic wear on the extinct carnivore teeth, the researchers apply a dental impression material to make a tooth mold. (Courtesy of Larisa DeSantis / Vanderbilt University)

Their analysis revealed that the wear pattern on the teeth of the American lion most closely resembled those of the present-day cheetah, which actively avoids bones when it feeds. Similarly, the saber-tooth cat’s wear pattern most closely resembled those of the present-day African lion, which indulges in some bone crushing when it eats. (This differs from a previous microwear study using a different technique that concluded saber-tooth cats avoided bone to a far greater extent.)

The researchers examined how these patterns changed over time by selecting specimens from tar pits of different ages, ranging from about 35,000 to 11,500 years ago. They did not find any evidence that the two carnivores increased their “utilization” of carcasses throughout this period. If anything, their analysis suggests that the proportion of the carcasses that both kinds of cats consumed actually declined toward the end.

The researchers acknowledge the high rate of tooth breakage reported in the previous study, but they argue that it is more likely the result of increased breakage when taking down prey instead of when feeding.

“Teeth can break from the stress of chewing bone but they can also break when the carnivores take down prey,” DeSantis pointed out. Species like hyenas that regularly chew and crack bones of their kills are as likely to break the rear teeth they use for chewing as their front canines. Species like the cheetah, however, which avoid bones during feeding are twice as likely to break canines than rear teeth. This suggests that they are more likely to break canines when pulling down prey.

Examples of the results of DMTA analysis of saber-toothed cat and American lion teeth. The lack of deep pits in the American lion teeth suggest that it avoided chewing on bones unlike the saber-toothed cat whose teeth show deeper pitting. (Courtesy of Larisa DeSantis / Vanderbilt University)

The researchers report that previous examinations of the jaws of the American lions and saber-tooth cats from this period found that they have more than three times as many broken canines and interpret this as additional evidence that supports their conclusion that most of the excess tooth breakage occurred during capture instead of feeding.

In addition, the researchers argue that the large size of the extinct carnivores and their prey can help explain the large number of broken teeth. The saber-toothed cats were about the size of today’s African lion and the American lion was about 25 percent larger. The animals that they preyed upon likely included mammoths, four-ton giant ground sloths and 3,500-pound bison.

Larger teeth break more easily than smaller teeth. So larger carnivores are likely to break more canine teeth when attempting to take down larger prey, the researchers argue. They cite a study that modeled the strength of canine teeth that found the canines of a predator the size of fox can support more than seven times its weight before breaking while a predator the size of lion can only support about four times its weight and the curved teeth of the saber-toothed cats can only support about twice its weight.

“The net result of our study is to raise questions about the reigning hypothesis that “tough times” during the late Pleistocene contributed to the gradual extinction of large carnivores,” DeSantis summarized. “While we can not determine the exact cause of their demise, it is unlikely that the extinction of these cats was a result of gradually declining prey (due either to changing climates or human competition) because their teeth tell us that these cats were not desperately consuming entire carcasses, as we had expected, and instead seemed to be living the ‘good life’ during the late Pleistocene, at least up until the very end.”

Contact:
David Salisbury, (615) 322-NEWS
david.salisbury@vanderbilt.edu


  • http://www.facebook.com/mcfenning Michael C. Fenning

    Humans kill everything, especially creatures considered a danger to themselves. The search for alternative explanations is simply attempting to find a cover for the true fact of human nature: we kill.

  • http://www.facebook.com/DogFaced Zack Shoemaker

    Perhaps they were dining too good, and became the meal.

  • http://twitter.com/JackieBrownz Jackie Brown

    Will scientists ever stop trying to deny the obvious fact that the so called harmonious Native Americans showed up in North America a short time ago to the last untouched paradise on Earth. The Americas.

    And proceeded to slaughter the pinnacle of the mammalian evolution into extinction and oblivion in a relentless blitzkrieg assault from Canada to Patagona. Worse than what happened to the dinosaurs and such a short time ago, we can still hear the echoes of the greatest and largest mammals who ever roamed this earth. The greatest of the mammalian order did not stand a chance against the most ruthless, invasive and destructive species the world has ever known. Humans.

  • Daniel Cheshire

    They went extinct only 12,000 years ago. Climate change was severe but it is more likely a combination of men killing them for food and their skin as well as the change in climate. They didn’t stand a chance. It was us or them. Survival of the fittest. Just evolution at work. Big cats do not mix well with people; that’s why their numbers are sadly diminishing. But the good news is that we’re the dominant species for the moment! Better than the alternative…

  • http://profiles.google.com/pcwag33 Pete Wagner

    Big cats should not logically be saber-toothed. I say hoax.

  • http://www.facebook.com/people/Graham-Mattison/71210513 Graham Mattison

    Here’s my theory. Look to Columbus. Feline Herpesvirus (FeHV) &
    Feline Immunodeficiency Virus (FIV) – Are both highly prevalent in African big cats – infection rates are often observed at 90%+ through out wild african populations. Both are seen as generally benign to African lions.

    In general, I would assume a deadly virus would have been the culprit most likely one that is transmitted through bodily fluids – saliva, urine, feces, semem, etc. – my bet is on herpes.

    Other megafauna likely could have suffered similar effects as Asian elephants. Asian elephants, when exposed to certain strains of herpes from African elephants, (A benign affect is observed in African elephants) experience internal hemorrhaging and death within as little as 5 days.

    http://www.cbsnews.com/2100-870_162-34463.html

  • http://www.facebook.com/travis.mcdaniel.37 Travis McDaniel

    Just goes to show you everything we know could be wrong.

  • http://www.facebook.com/people/William-Harper/100001250824530 William Harper

    Look at the larger Clovis points and consider the use of the atlatl with Folsom points by teams of expert Humans. The animals the big cats fed on would have been killed. The cats themselves would have been killed. There is a tendency to underestimate the lethality of the spear. Also consider that bows have been found in the Old World and C14 dated to 12,000 BP. There is plenty of evidence that Homo sapiens was master of the Ice Age world by 30,000 B.P..

  • Terrence Kaufman

    I think I need to chew on this “‘not” starvation’” theory for a while. Sounds rather like something I would see on the History Channel not in a biology text.

  • per89

    Where did they get the notion that “prey” animals were in decline? Seems to me that by the end of the great ice ages, prey animals would have been increasingly plentiful due to the increase in grazing land in the northern hemisphere. Deer, antelope, bison, elk would have all numbered in the tens of millions by the time Europeans hit the continent. And that despite increasing populations of aboriginals. Wolves and other smaller feline predators made it in spite of climate change and human competition. Physical size doesn’t seem to be a factor either. Bison, moose, and large old world cats all made it. I think that it is rather obvious that other unknown natural factors played into the demise of the saber-toothed cats in the Americas. 99.9% of all species that ever lived were extinct before humans arrived on the scene. The scientific community is so arrogant in its assumption that humans are always at fault for naturally occuring ebbs and flow in the biosphere.

  • http://www.facebook.com/bert.mcdirt Bert McDirt

    uh, hello, poleshift…

  • http://www.facebook.com/profile.php?id=100003533488721 David Bortfeld

    Given the large number of bison roaming the American West during the taming of the 1800s, it seems there were plenty of dining choices for the big cats, casting doubt to the “tough times” theory.

    • http://www.candleforex.com/ CandleForex

      The article was talking about over 12,000 years ago. The the cats in question were long gone before the 1800′s.

  • Chuck

    Interesting. So, if the evidence toward the end points toward these animals bringing down bigger prey, then they would also be less likely to eat on the bones because they would be full. Normally, they would have been eating smaller prey and ate at the bones a little.

    If the smaller prey was disappearing, where was it going? Since they bigger prey seemed to have been there, was the smaller prey disappearing because newly arrived humans were starting to deplete it? Or was some weather condition killing off the smaller prey but not the bigger?

    Either way, this is very interesting stuff.

  • Guest

    Saber tooth cat! Told you, Maya!

  • http://www.facebook.com/people/Wilf-Tarquin/100003677547260 Wilf Tarquin

    The most effective predator the Earth has ever seen invades a new continent, in the next thousand years nearly all large-to-very-large animal species go extinct, but hardly any small animals or plants.

    Clearly the species which went extinct… uh… starved. Because of the ice age. Which was, ummm, somehow different than the dozen or so other glaciation cycles they had already survived.

    Yeah, that’s the ticket.

  • http://www.candleforex.com/ CandleForex

    Very interesting. So whats the new theory or explanation then for their extinction?

  • ChuckTerzella

    Maybe they went vegan…it nearly killed me when I tried it.

    • Azi Smythe

      excellent!

  • http://www.facebook.com/jeff.vachon Jeff Vachon

    I suspect a virus killed these creatures off. For lack of any other reason.

  • http://www.facebook.com/people/Pete-Draganic/1536174014 Pete Draganic

    Is it simply possible that they succumbed to disease?

  • Rex Havoc

    Clearly the cold snap at the end of the late Pleistocene period was too much particularly since the Flintstones were in the habit of putting the cats outside at night.

  • Arthur Valla

    The Saber Toothed Tiger died of starvation. In the Flintstones, at the end of every show, Fred puts out the cat, which then jumps through the window and locks Fred out of the house.

    But Fred never feeds the cat. He feeds Dino the dinosaur, but never the cat. In fact, I don’t think the cat even has a name.

  • Azi Smythe

    Really interesting stuff for me, once a zoology major, who hasn’t formally worked or studied the field in many years…..but really loved that senior evolution course they made me take! This article considers famine/competition as a cause of the population’s demise. Predation doesn’t seem likely, but disease has always seemed to me a possible contender for gulity party.

  • http://www.facebook.com/sam.england.167 Sam England

    I’d still bet that neolithic man had something to do with the extinction of the great cats of North America. From the time of the crossing of the Bering Strait, until we reached Tierra del Fuego, how long did it take? About 1,000 or so years?

    (Notice I say, “we”, as all humans alive today share a common ancestor female who lived in East Africa about 100,000 years ago.) We’re all in this together.

  • http://www.facebook.com/people/John-Nicoletti/100002104523712 John Nicoletti

    …I think it was those guys with the spears….lol…………

  • http://twitter.com/AzalpYerbua Azalp Yerbua

    They were done in by a change in their health care system.

  • EllenWedum

    So this re-opens the puzzle of their extinction.

  • http://profiles.google.com/craigbhill craig hill

    At some point perhaps evidence of arrowheads and bashed-in heads of smilodon may cue us to their demise. If not the first humans in the Americas, how else???

  • Larry Burfield

    So, Why did the large cats survive in Africa, with more human and animal competition for everything? Did North America have some unknown blight?
    burfield@aolcom

  • http://twitter.com/tim333 Tim S

    Guess the humans wiped them out along with the dodos, mammoths, most of the bison and numerous other species

  • LevonTostig

    They fed well… Off each other.

  • Htos1

    Not starvation,or hunting,a catastrophic climate event.

  • rob

    Maybe God sent a flood to wipe out all creatures. 12000 yrs ago would pretty much correspond perfectly with the bible’s account.

  • lloyd lloyder

    there has been more nd more evidence coming to light about a large asteroid breaking up over the eastern portion of Canada and causing a catastrophic event that made life in north america impossible for any larger living thing. This is an ongoing project and would account for the decimation of all the larger animals; including human; clovis man, that inhabited north america at that time and coincides with it. Knowledge network had a peice about it recently showing. The same trace elements that are indicators of this type of event are being found in the right age range. Nature doesn’t play favorites, if you are in the wrong place at the wrong time, that’s it.