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History of "Jeff" The Giant Ground Sloth

“Jeff,” the informal name of the giant ground sloth skeleton in the Orton Geological Museum, is one of Ohio State’s most distinctive and recognizable images. Images or descriptions of it span an array of scientific papers, promotional literature, artistic imagery, and digital media. Viewed by >25,000 visitors annually, it is one of the most impactful teaching and outreach tools in the Orton Museum, although few know the skeleton’s backstory, or its significance in the annals of science. This skeleton is connected to the early history of paleontology in the United States. Here is part of that story.

On March 10, 1797, Thomas Jefferson presented “A Memoir on the Discovery of certain Bones of a Quadruped of the Clawed Kind in the Western Parts of Virginia” to the American Philosophical Society. Published in 1799, the paper includes the naming of the first genus of fossil animal, Megalonyx (“giant claw”) from the USA. Together with an accompanying paper by Caspar Wistar describing and illustrating the fossil material, these papers mark the beginning of the science of paleontology in America.

Jefferson’s 1799 paper presents results of one of the earliest quantitative paleontological studies, a study published long before the word “paleontology” was coined in 1822. He cited the enormous dimensions of Megalonyx to counter the theory of New World degeneracy championed by Georges-Louis LeClerc, Comte de Buffon, who as one of the leading naturalists of the late 1700s, authored some of the earliest literature on animal evolution and geological history. Buffon argued that all life forms in the New World, particularly North America, were degenerate (weaker, smaller, and feebler) than in the Old World, a function of the supposed pernicious effects of a cold, humid climate. Jefferson, in the main body of his paper, dated February 10, 1797, initially mistook the Megalonyx for a carnivorous animal. He compared the dimensions of his “giant claw” to a large African lion, an animal that he showed to be approximately 30% smaller than Megalonyx. In a postscript dated March 10, 1797, he changed his interpretation of the affinities of Megalonyx, drawing a comparison to Megatherium, a giant sloth whose skeletal remains from Argentina were illustrated by the French naturalist Jean Léopold Nicolas Frédéric, Baron Cuvier, better known as Georges Cuvier, the founding father of paleontology. Cuvier showed that Megatherium had the simple, cylindrical teeth of a herbivore, rather than the dagger-like teeth of a carnivore. Jefferson, writing about the possible relationship of Megalonyx to Megatherium, stated “But to solve satisfactorily the question of identity, the discovery of fore-teeth, or of a jaw bone showing it had, or had not, such teeth, must be waited for, and hoped with patience.”

Thomas Jefferson championed the idea that Megalonyx and the mastodon (the name given by Cuvier to the ancient animal then commonly known as the Incognitum, Mammut americanum) were giant land mammals that continued to live in as-yet unexplored parts of the North American continent. Following the Louisiana Purchase from the French Republic in 1803, Jefferson, now the US President, commissioned Meriwether Lewis and William Clark to lead an expedition, called the Corps of Discovery Expedition (1804), to explore and map the Louisiana Territory, find a practical route to the western part of the continent, and establish an American presence in areas west of the Louisiana Territory that were as-yet unclaimed by European powers. They were also instructed to return with evidence of live mastodons and giant ground sloths.

Lewis and Clark’s expeditionary group returned from the Louisiana Territory in September 1806 without a living mastodon, and without a living Megalonyx. Today we recognize that giant ground sloths are extinct, as are other emblematic Pleistocene mammals such as mammoths, mastodons, dire wolves, and sabre-toothed cats. Extinction apparently occurred in the midst of global climatic change associated with deglaciation of Northern Hemisphere continents, and expansion of human populations across these areas in the late Quaternary Period (Late Pleistocene-Early Holocene). This episode in Earth history is known as the Quaternary Megafauna Extinction.

In 1890, the first substantial skeletal remains of a Megalonyx were unearthed from a farm in Holmes County, Ohio. While digging a drainage ditch, workers first encountered bones, and threw them aside, on or about November 28. Approximately 1/3 of a skeleton was unearthed on December 19, before heavy snowfall the following day thwarted further excavation. The esteemed geologist, Edward Orton, then President of The Ohio State University, visited the site on December 27, and four days later (December 31, 1890) read a paper on the discovery of the Holmes County Megalonyx at the third meeting of the Geological Society of America in Washington, D.C. The paper was published in Scientific American on January 10, 1891. In it, Orton addressed Buffon’s theory of New World degeneration, noting the “truly gigantic” size of a ground sloth. Also on January 10, 1891, E.W. Claypole of Buchtel College (now University of Akron), visited the excavation site. His observations were published in March, 1891. The swift publication of these preliminary studies underscores the perceived scientific importance of the skeletal remains at the time. Among the remains unearthed were three teeth (molars), which confirmed earlier observations that Megalonyx had teeth similar in shape to those of Megatherium, and that Megalonyx was a herbivore, as hypothesized by Thomas Jefferson in the postscript to his 1799 paper (penned in 1797).

The Holmes County Megalonyx remains were donated to The Ohio State University (catalog number OSU 15758). The skeleton was complete enough that details could be filled in from casting remains found elsewhere, or by modeling them after Megatherium from South America. Through the generosity of the Columbus-based entrepreneur Emerson McMillin, the skeleton was mounted by Ward’s Natural Science Establishment, in Rochester, New York. In 1896, the mounted skeleton went on display in the Orton Geological Museum, where it still stands today. Except for a brief period when it was loaned to the Ohio History Center (1982-1984), the skeleton has been on display continuously in Orton Hall since 1896. For generations, the skeleton has been known informally as “Jeff,” short for Megalonyx jeffersonii (the species name honors Thomas Jefferson).

The Holmes County ground sloth has the distinction of being the first mounted skeleton of Jefferson’s Megalonyx. “Jeff” is the oldest exhibit, and one of the most photographed, in the University. Illustrations of it have been widely disseminated since it first went on display. It is fascinating that the skeleton was mounted as though the animal were bipedal, resting or dragging its tail on the ground, rather than walking on all fours with the tail elevated, as you might expect of a herbivorous mammal. Speculatively, the configuration of the mount may have been influenced by Jefferson’s original misinterpretation of the animal as a giant carnivore, one that could rear on its hind legs like a bear. Placement of the tail on the ground would have provided structural support for the mount. Whatever the reason, until recently most Megalonyx skeletons mounted in the years since “Jeff” was unveiled were engineered in similar fashion. Nowadays it is more common to mount ground sloth skeletons in a quadrupedal habit, and recent artists’ reconstructions more commonly depict ground sloths as quadrupeds.

Megalonyx jeffersonii as a species may be extinct, but “Jeff” is a survivor of sorts. It was among the earliest free-standing prehistoric animal skeletons displayed in American museums. The first mount, a Pleistocene mastodon (Mammut americanum) from New York, completed under the direction of Charles Willson Peale in 1802, was disassembled, and remounted later in Darmstadt, Germany. Two other mastodon skeletons, first mounted in 1841 (from Missouri) and 1867 (from New York), likewise have been remounted. Three Eocene whale skeletons from Alabama, Basilosaurus cetoides (aka Zeuglodon, and Hydrargos or Hydrarchos) mounted between 1845 and 1895, have been disassembled, destroyed, or remounted. And the first mounted dinosaur, Hadrosaurus foulkii, from New Jersey, originally mounted in 1868, has been disassembled and reconfigured. “Jeff” the Megalonyx is still in its original 1896 mount, although a tree trunk, part of the original display, has been removed, and part of the steel support has been bent slightly from its original position. As such, “Jeff” seems to be the oldest, surviving, free-standing mount of a large prehistoric animal in America.