Thomas Jefferson's Monster, by B.J. Hollars

Thomas Jefferson’s Monster

By B.J. Hollars

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In April of 1796—nearly three years after resigning his post as Secretary of State—Thomas Jefferson received an unexpected package from Colonel John Stuart of Greenbrier County, Virginia. Curious, he opened it, taking note of the letter within.

“Being informed you have retired from Public Business and returned to your former residence in Albemarle,” the colonel wrote, “and observing by your Notes your very curious desire for Examining into the antiquity of our Country, I thought the Bones of a Tremendous Animal of the Clawed kind lately found . . . might afford you some amusement. . . .”

Certainly, he was in need of some. Since retiring from the political spotlight, Jefferson had recommitted himself to a few of his earlier passions—agriculture, architecture, and natural history—while also dedicating time to his clover field. All of which brought him joy, no doubt, but none of which gave him what Colonel Stuart’s package did.

Upon reaching deeper into the package, Jefferson discovered several bone fragments, including three large, unidentifiable claws. Jefferson eyed the bones with astonishment. He had seen marvels the world over, yet he’d never seen a marvel quite like this.

Was it possible that a creature of such terrifying proportions once roamed the American landscape? And was it possible—however remote—that such a creature might still exist?


Despite French political thinker Alexis de Tocqueville’s 1835 remarks on American exceptionalism, not all his countrymen felt similarly. One of America’s chief critics was French naturalist George-Louis Leclerc, Comte de Buffon, who wondered, quite publicly, what exactly made the fledgling country exceptional. Certainly not its flora and fauna.

In 1781 Buffon made his case, publishing a 36-volume encyclopedia entitled Histoire naturelle, a comprehensive look at the natural world, including commentary on what would become known as Buffon’s Theory of Degeneracy—the idea that North American creatures were wholly inferior to their overseas counterparts. In the Old World, Buffon argued, species were bigger, stronger, and at the very least, existed, whereas “[t]he horse, the ass, the zebra, the elephant, the rhinoceros, and the hippopotamus, had no existence in America.” Buffon added that in the instances in which the Old and New Worlds shared a species, these species were typically “smaller in the latter.” He attributed America’s menagerie of second-rate creatures to the New World’s inhospitable climate—a damp, swampy place, he concluded, that provided little more than a refuge for mosquitoes and snakes.

Francophile though he was, Jefferson’s allegiance was for the home team. As such, he was expectedly frustrated by Buffon’s theory. Not only because he believed it to be wholly unsubstantiated, but also for the insinuation left festering beneath the surface. If Buffon argued that the animals of the Americas were the weakest of their species, what might he be implying of its human inhabitants? French philosopher Abbé Raynal seized on Buffon’s rough treatment of the New World, adding that its people had failed to produce “one good poet, one able mathematician, one man of genius in a single art or a single science.”

Buffon and Raynal’s theories of America’s inferiority demanded a rebuttal, and Jefferson was happy to oblige. Four years after Buffon published Histoire naturelle, Jefferson published Notes on the State of Virginia, a scientific-based love letter boasting the wonders of his home state, and by extension, America as a whole. Initially, Jefferson had been inspired to write it at the request of another Frenchmen, François Barbé-Marbois, who posed questions on various facets of colonial life—from geography and geology to the economy and the laws. Jefferson’s eloquent responses provided a strong defense for America’s standing, and further solidified him as a worthy spokesperson for the nation. Not only did Jefferson exemplify the American spirit, but he possessed the scientific and rhetorical skills to persuade one hemisphere that the other was a force to be reckoned with. And, of course, Jefferson himself was a force. As historian James Parton remarked in 1874, “If Jefferson was wrong, America is wrong. If America is right, Jefferson was right.” That the fate of a country was placed on the shoulders of a single man seems like lunacy, yet Parton was hardly alone in his assessment. Today, we can’t celebrate just how right Jefferson was without mentioning just how wrong he was, too. Most notably, how the man who had professed that “all men are created equal” had failed to put his claim into personal practice.  

Jefferson was far more comfortable defending what was defensible, countering Buffon’s Theory of Degeneracy by noting that America was home to some of the biggest palmated elk and moose the world had ever seen, and far larger than their equivalents in Europe.

In the off chance that his elk/moose argument didn’t send Buffon trembling, Jefferson made reference to the mighty American mammoth as well. After all, if Buffon’s Theory of Degeneracy was correct, then where were Europe’s mammoths? Had any been spotted strolling in the Gardens of Versailles? Along the Champs Élysées?  

“It may be asked, why I insert the Mammoth, as if it still existed?” Jefferson wrote. “I ask in return, why I should omit it, as if it did not exist?” He reminded readers (though mostly Buffon) that much of the American West remained “unexplored and undisturbed” and remained optimistic that the mammoth “may as well exist there now.”

(When dispatching Meriwether Lewis and William Clark in 1804, Jefferson encouraged the western expedition to keep an eye out for mammoths).

While Jefferson attacked the French flank with his Notes on the State of Virginia, he waged a frontal assault by bestowing upon Buffon physical proof of America’s dominance in the animal kingdom—presenting him with a panther skin, mastodon bones, and after much searching, the finest dead moose the country had to offer. Measuring in at over seven feet tall, the moose’s skin and bones arrived at Buffon’s doorstep in October of 1787.

As Jefferson had hoped, it was impossible to argue with a dead emissary of such an impossible size.

What could the French naturalist say but that he was wrong?

In conceding, Buffon ensured that America’s most glorious moose had not died in vain. Buffon promised to set the record straight, though he died before he had the chance to.


By 1796, America had much to be proud of. Over the course of two decades it had grown from 13 disjointed colonies under British rule to a fully functioning country, one whose military, economy, and system of government would become the envy of the world.  

Nevertheless, Buffon’s dismissiveness of the New World’s flora and fauna remained firmly stuck in Jefferson’s craw. Since Buffon’s death ensured that he was no longer in a position to restore America’s honor, Jefferson sought other means to right the perceived wrongs wrought upon the nation. An opportunity presented itself with Colonel John Stuart’s 1796 package. What better than a giant, unknown creature to disprove Buffon’s Theory of Degeneracy once and for all? In Colonel Stuart’s opinion, he believed the bones belonged to an animal “of the Lion kind. . . .” Following his own careful assessment, Jefferson came to the same conclusion, believing the fragments likely belonged to an undiscovered American lion which he dubbed the megalonyx or, more informally, “Great-claw”—a reference to the eight-inch claw included in Stuart’s package. Jefferson’s “lion” classification was based on several scientific factors, though perhaps his conclusion was also the result of a psychological one—his desire to believe that a giant, carnivorous, quadruped once roamed freely along the American landscape. Buffon and the Old World could keep their rhinos and hippos; the New World was home to an enormous lion.

Anxious to make his findings public, on July 3, 1796—just three months after receiving the bones from Stuart—Jefferson wrote to American Philosophical Society president David Rittenhouse to inform him of having come into possession of bones belonging to a creature in the family of “the lion, tiger, panther &c but as preeminent over the lion in size as the Mammoth (mastodon) is over the elephant.”

Had he been alive to read it, Rittenhouse would have been shocked by the claim that such a creature once marauded in America, though his death the previous week ensured that the mystery of the megalonyx remained unknown to him. News of Rittenhouse’s death hadn’t yet reached Monticello, and when Jefferson’s letter arrived in Philadelphia, Rittenhouse’s nephew, botanist and fellow society member Benjamin Smith Barton, gladly read its contents to the American Philosophical Society. Today, we can only speculate whether Rittenhouse would have done the same. Or if, instead, Rittenhouse might have served as a much-needed check to balance Jefferson’s unbelievable claim.

Yet “what-might-have-been” is not nearly as important as what actually transpired: Jefferson’s letter was read aloud to the society, and it proved of such interest that Barton asked to publish Jefferson’s findings in the forthcoming issue of Transactions of the American Philosophical Society.

Jefferson was pleased by the news though he remained somewhat dissatisfied by his initial assessment of Great-claw. Stuart’s bones were simply the start, and in order to better gauge the lion’s unbelievable hulk, Jefferson required a more substantial piece of the puzzle. A thighbone was rumored to be “still in the neighborhood” where the other bones had been found, and with Barton’s promise to push back the publication deadline, Jefferson dispatched Colonel John Stuart to scour Greenbrier County to find the missing piece.

In his November 1796 letter to Stuart (in which he pleaded for a thighbone with the same gusto he’d previously reserved for America’s independence), Jefferson admitted his belief that the Great-claw wasn’t simply a monster of the past, but a living, breathing creature of the present. “I cannot . . . help believing that this animal, as well as the Mammoth, are still existing,” he admitted privately to Stuart. “The annihilation of any species of existence is so unexampled in any parts of the economy of nature which we see, that we have a right to conclude, as to the parts we do not see, that the probabilities against such annihilation are stronger than those for it.” Believing it unlikely that nature could exterminate an entire species (this was 60 years before Darwin), Jefferson continued to believe that the megalonyx (as well as the mammoth) lived somewhere west of the Mississippi River.

“The animal species which has once been put into a train or motion,” Jefferson later argued before the American Philosophical Society, “is still probably moving in that train.”

It was a bold supposition—transporting ancient creatures into the modern day on the evidence offered by a few unclassified bones. Yet Jefferson’s “train or motion” argument managed to win over several society members, many of whom—Jefferson included—were not ready to discount the marvels that might still await them in the West.


Thomas Jefferson was neither the first nor the last to romanticize the American West. Yet by authorizing the Louisiana Purchase in 1803, he did what few before him had—bet bullishly that the romance was real. Of course, the fur traders had turned the West into big business, but Jefferson believed its value transcended the bottom line. America now had in her possession hundreds of thousands of unexplored miles to map, and who could imagine what wonders might await?

Engraving of the bones shipped to Thomas Jefferson.
Engraving by James Akin, published in Caspar Wistar’s “A Description of the Bones Deposited by the President, in the Museum of the Society, and Represented in the Annexed Plates,” Transactions of the American Philosophical Society (Vol. 4), 1799.
Image courtesy JSTOR.

Unknown creatures weren’t the only things shocking Americans that year. In 1796, Jefferson surprised many by reneging on his swearing off of politics, and in a dramatic shift, challenged John Adams for the presidency of the United States. After losing by three electoral votes, Jefferson reluctantly accepted the vice-presidency.

However, his spirits were buoyed by another office bestowed upon him in the days following the March inauguration: president of the American Philosophical Society. Though the two honors occurred in close succession, in a letter to the secretaries of the APS Jefferson remarked that “the suffrage of a body which comprehends whatever the American world has of distinction in philosophy and science in general is the most flattering incident of my life.”

As for the vice-presidency, Jefferson grumbled to then-congressman James Madison that it was “the only office in the world about which I am unable to decide in my own mind whether I had rather have it or not.”

Upon arriving in Philadelphia in March of 1797 to assume his vice-presidential duties, Jefferson wandered into a local bookstore to discover a megalonyx staring back at him from the pages of Monthly Magazine. The accompanying article noted that the skeleton had recently been excavated in Paraguay, French zoologist Georges Cuvier dubbing Jefferson’s megalonyx a megatherium—not a lion but a sloth.

The unwelcome discovery forced Jefferson to reevaluate his classification. Had he—in his haste to disprove one Frenchman—been proven wrong by another? Had he miscalculated? Misidentified? Transformed a harmless herbivore into a carnivorous beast?

“For millions of years the bones of the megalonyx and megatherium had lain unnamed and undisturbed on their separate continents,” Princeton historian Julian Boyd wrote in a 1958 article. “Now, within the space of a single week, they had collided on the streets of Philadelphia, bringing understandable agitation to the president-elect of the Society.” The irony was hardly lost on Jefferson, whose agitation was great. In an effort to offset it, he immediately began revising his article, as well as adding a postscript that, in retrospect, undercut much of the remainder of his argument.

Jefferson’s postscript made clear that the giant lion of his imagination was just one possibility among many. While Cuvier’s discovery was “not of the cat form” (it more closely related to sloths, armadillos, and anteaters), this only proved problematic, Jefferson believed, if the two creatures turned out to be one in the same. While Jefferson acknowledged that the creatures shared many discernible features related to bone structure, he felt it best to refer to them separately until proven otherwise. He called for further study, believing—and perhaps hoping—that the world was big enough for both creatures to exist.


Throughout his life, Jefferson had often reveled in the vastness of the world, not to mention its many mysteries. Growing up in Virginia, he could often be found wandering the woods and the hillsides in search of plants and animals, arrowheads and bones. “Wherever he lived,” wrote historian Robert Morgan, “his home resembled a museum.” This was due, in part, to Jefferson’s friends and acquaintances, many of whom had been making gifts of their discoveries for decades. John Stuart’s “Bones of a Tremendous Animal of the Clawed kind” were hardly the first bones Jefferson ever received. Thirteen years prior, in 1783, General George Rogers Clark (not to be confused with William Clark of Lewis and Clark fame) procured for Jefferson several teeth and bones believed to have come from a mammoth. Jefferson thanked Clark for the gift, adding, too, that he would “cheerfully incur the necessary expences of good package and carriage” of any other bones should they be found.

Jefferson’s insatiable curiosity had long worked to his advantage, though in the case of the megalonyx, it proved to be a liability, too. Despite the last-minute changes that resulted from his serendipitous perusal of Monthly Magazine, Jefferson remained committed to giving his presentation to his colleagues at the APS. On March 10, 1797, he read his remarks before the society members, acknowledging the bones’ relative similarities to that of the lion, and promising to compare the size of a lion’s bones alongside those belonging to Great-claw. If his comparisons proved correct (and by now he was likely doubting them), then the megalonyx measured in at “more than three times as large as the lion.”

After offering his evidence, Jefferson confronted the questioned weighing heavily on the society members’ minds: What became of the creature?

And that’s when the vice-president of the United States of America offered a rather astonishing theory.

“In the present interior of our continent there is surely space and range enough for elephants and lions, if in that climate they could subsist: and for the mammoths and megalonyxes who may subsist there,” Jefferson claimed. “Our entire ignorance of the immense country to the West and the North-West, and of its contents, does not authorize us to say what it does not contain.”

As further proof of the megalonyx’s reign in America, Jefferson referenced an ancient rock carving found near the Kanawha River—a tributary of the Ohio—that depicted what had “always been considered as a perfect figure of a lion.”

“May we not presume that prototype,” he asked, “to have been the great-claw?”

Jefferson’s tenuous connection between a few bones and a sketch on a rock wall swayed few to his cause, though he added further credence to his claims by way of good old-fashioned storytelling.

The first story took place in Greenbrier County sometime in the 1760s, when the “terrible roarings” of an unknown creature was said to have terrified a group of explorers. Dogs and horses trembled alongside their men, the entire expedition horrified by what they saw peering back at them—an “animal unknown” with “eyes like two balls of fire.”

Jefferson’s second tale featured a pair of hunters, George Wilson and John Davies, both of whom were hunting near Virginia’s Cheat River in 1765 when they were said to have heard a roaring that made “the earth tremble under them.” Once more, dogs cowered while the monster “prowled round their camp for a considerable time.”

Jefferson saved his most spellbinding tale for last, recounting the story of an outdoorsman named Draper who, while hunting along the Kanawha River in present-day West Virginia, tied a bell around his horse’s neck and allowed it to roam freely. Upon hearing the frantic ringing of the bell sometime later, he rushed to the horse’s aid to find it “half eaten.” Draper’s hunting dog gave the predator chase, though when Draper himself caught a glimpse of the “terrific bulk” he noted that its outline resembled “those of the cat kind”—not unlike Jefferson’s megalonyx.

Despite society members’ enthusiastic response, Jefferson remained troubled by what he’d discovered just days prior in Monthly Magazine. He offered the bones to the society for further study, charging botanist Caspar Wistar with the task of examining the clues.

In the very issue of Transactions of the American Philosophical Society in which Jefferson claimed Great-claw to be a giant lion, Wistar offered the alternative version: that it was a giant sloth, instead. “The sloth has but two phalanges in addition to the supported metacarpal bone,” Wistar explained, “whereas the animal in question has bone No. 2 and two phalanges besides.” For Wistar, the creature’s classification came down to the number of bones in the toes of an unknown beast. Wavering dangerously close to the truth, he noted the inclination to compare Jefferson’s lion-like megalonyx to Cuvier’s sloth-like megatherium, though remaining loyal to his society president, wrongly concluded that they were likely not the same creature.

The truth became evident soon after. With a single contrary determination, Georges Cuvier had transformed Jefferson’s giant lion into a giant gaffe—an error that long haunted the American. “One of the marks of a good scientist is patience, tenacity, and willingness to try again and again,” Robert Morgan wrote in reference to Jefferson’s interest in the bones of extinct species. While Jefferson certainly demonstrated the latter qualities, when it came to the megalonyx, his patience appeared to be lacking.

Half a century later, in Joseph Leidy’s A Memoir on the Extinct Sloth Tribe of North America, the author attempted to downplay Jefferson’s error, calling it “a mistake of much less importance than many made by the best naturalists.”

Leidy’s defense seemed to cut both ways, implying, perhaps, that Jefferson was not among them.


Jefferson’s redemption came in the early 20th century, when bones belonging to Panthera leo atrox were pulled from Los Angeles’s La Brea Tar Pits. The American lion (though some paleontologists believe it to have more closely resembled a jaguar) was a quarter larger than the modern lion, its powerful forelegs and retractable claws a deadly combination. With a hefty male weighing in at over 500 pounds, it’s no wonder Jefferson believed his great-clawed creature was capable of putting the French in their place. He had dreamed the right creature, it turned out, but he’d dreamed it with the wrong creature’s bones.

Jefferson—witness to a revolution, writer of a declaration—had watched his country outgrow his imagination time and time again. And so, when she offered him a giant claw, who was he to doubt that it belonged to anything less than the greatest lion the world had ever known? He believed her, instead—his misclassification not born solely from scientific sloppiness, but also an unharnessed, imaginative gusto. Might we chalk up his error to a kind of Manifest Destiny of the mind? Some misguided belief that America was deserving of such a creature, regardless of whether or not it existed?

While disappointed by his error, perhaps he was equally disappointed by what had spurred it—men like Buffon and Raynal who, in the latest front of geopolitical warfare, now wielded science like a weapon.

It was a weapon that Americans were hardly above using themselves. Yet in Jefferson’s rush to do so, he confused faith with facts, asking more of his country than its ecosystem could bear. Jefferson found no lion, though this hardly kept him from refashioning the bones to construct a creature to his liking.

Jefferson believed what Tocqueville did: that America was exceptional. But in this instance, his attempt to prove it to the world seemed to confirm the opposite. Can we forgive a man for dreaming big and falling short? And can we forgive a country for doing the same?

How many enslaved Africans would it take for 19th century Americans to concede their exceptionalism? And what would it take for Jefferson to acknowledge his own role in perpetuating an institution that ran counter to the ideals he’d helped dream into existence?

Shortly after his misidentification of the megalonyx, Jefferson managed to identify the true monster. One that never lurked in a cave or skulked throughout the American West. Rather, this monster paraded about in broad daylight.

It still does.

In a letter dated January 1, 1797—in the midst of accepting his runner-up prize of the vice-presidency—a politically disheartened Jefferson wrote once more to Madison. “I do not recollect in all the animal kingdom a single species but man which is eternally and systematically engaged in the destruction of its own species,” he admitted. “. . . [L]ions and tigers are mere lambs compared with man as a destroyer.”


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—. Letter to Col. John Stuart. 15 Aug. 1797. The Writings of Thomas Jefferson. Ed. Albert Ellery Bergh. Washington, D.C.: The Thomas Jefferson Memorial, 1907.

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