Ohio's Ice Age animals

At a glance

The mastodon capital of the Midwest

Nearly all dated Ice Age animal remains from Ohio fall between about 18,000 and 10,000 years ago, as the state's last glacier was withdrawing. The state Geological Survey's own list of Ohio Pleistocene mammals, compiled by geologist Michael Hansen in 1992, includes American mastodon, mammoth, giant beaver, stag-moose, giant short-faced bear, flat-headed peccary, Jefferson's ground sloth, caribou, muskox and horse, among 38 mammal species in all.

The American mastodon (Mammut americanum) is by far Ohio's best-represented Ice Age animal. Remains of more than 150 individual mastodons have been reported across the state, though only about a dozen are semi-complete skeletons; the state Geological Survey put the number at "perhaps 200" in 1994 and counted nearly 250 proboscidean records — mastodon and mammoth combined — from 70 of Ohio's 88 counties in 1992, with mastodon remains outnumbering mammoth by roughly 3 to 1. A typical mastodon stood about 10 feet at the shoulder, ran 16 feet long, and weighed 4 to 5 tons; living animals were covered in coarse brown hair, an adaptation to the cold, according to Wikipedia's account of the Burning Tree Mastodon.

The single most important Ohio mastodon find is that Burning Tree Mastodon. On December 12, 1989, a drag-line operator digging a new pond on a golf course in Heath, Licking County, struck and damaged a skull with his shovel. The Ohio Historical Society, the Licking County Archaeology & Landmarks Society and volunteers excavated the skeleton over the following three bitterly cold days. It proved 90 to 95 percent complete — described as the most complete American mastodon skeleton ever found — from an animal about 30 years old at death, radiocarbon-dated to roughly 13,300 calendar years ago. Near an articulated series of ribs and vertebrae, excavators found a cylinder of preserved intestinal contents about 12 centimeters across and 60 centimeters long; the plant remains inside — twigs, moss, seeds, leaves, water lilies and swamp grass — undercut the older view that mastodons ate mainly evergreen twigs and cones. A 1998 study cultured nearly 300 bacterial isolates, representing 38 taxa, from the intestinal mass and surrounding sediment; enteric bacteria were concentrated in the intestinal material, but the researchers wrote that whether these organisms descended from the mastodon's own gut microbes "cannot be established," as reported in Applied and Environmental Microbiology. Investigators also reported cut and gouge marks, out-of-place grit and striations on some bones, and proposed that people butchered the animal nearby and cached the meat in the pond — but no stone tools or flakes were found, and a 2016 scholarly review concluded that "human agency also remains a question." The skeleton itself left Ohio: it was sold in 1993 for more than $600,000 and now resides in a museum in Japan.

Other major Ohio mastodons tell their own stories. The Johnstown Mastodon was found by accident on August 12, 1926, in a marshy pasture near Johnstown, Licking County, when a tenant farmer and the farm's owner, burying two hogs that had drowned in a watering trough, struck a tusk with their spades instead, according to the Cleveland Museum of Natural History. The farm owner charged onlookers a parking fee — rising from a dime to a quarter within days, clearing him $1,000 — and turned down a $1,000 purchase offer from the Ohio Archaeological and Historical Society; license plates from seven states were recorded at the site, and one wire-service report garbled the find into a "giant reptile" that had supposedly fought the mastodon. The Cleveland Museum of Natural History bought the skeleton at the end of 1926 for $5,300, paid for by a Cleveland paving executive on condition it be shown at Cleveland's Luna Park amusement park for two summers; it drew poorly in 1927, the park asked the museum to take it back in February 1928, and it became the museum's own logo for decades.

The Conway Mastodon, found in 1887 on a farm on the Clark-Champaign county line, is about 70 percent complete; the finder presented it to Ohio State University in 1894, and it has been on loan to the Ohio History Connection since 1970, standing at the entrance of the natural history exhibit at the Ohio History Center in Columbus. The Williams Mastodon was excavated in 1954 in Columbus during a house-foundation dig, when a construction worker struck bones an employee first mistook for cattle remains. Decades later, the excavator's granddaughter spent 15 years trying to trace what had happened to "her grandfather's mastodon," contacting universities and the Smithsonian without success, before the Ohio History Connection confirmed in 2020 that it had held the skeleton — plus a dozen 1954 excavation slides — the entire time; the family finally saw the bones in person on November 1, 2021, 67 years after the dig, and some tusk fragments are still wrapped in the original 1950s newspaper used to stabilize them, according to the Ohio History Connection.

Ohio's own named beast

The giant beaver, Castoroides ohioensis, is one of Ohio's best Ice Age hooks, because the state's own name is built into its species name. It was first found in 1837 near Nashport, Muskingum County, and described the following year by geologist J. W. Foster in the state Geological Survey's 1838 annual report, according to the Ohio History Connection. A mature Castoroides was roughly the size of a black bear, but there is no evidence so far that it cut down trees or built lodges the way modern beavers do; what it actually used its massive incisors for was, as of 2014, still being studied through bone chemistry. The state Geological Survey counted at least 11, and possibly 12, individuals known from Ohio as of 1992.

The cave with 75 species

One sinkhole in Wyandot County has produced one of the richest single Ice Age fossil assemblages in the eastern United States. Sealed by glacial deposits more than 10,000 years ago and rediscovered in 1989, the site was excavated by paleontologist Greg McDonald of the Cincinnati Museum of Natural History from 1990 to 1995; after later finds showed signs of human activity, archaeologist Kenneth Tankersley of Kent State led a National Science Foundation-funded excavation beginning around 1997. Strata radiocarbon-dated to roughly 11,000 to 10,400 years ago held two carved and beveled bone projectile points, a small reworked fluted stone point, cut and burned bone, and the remains of flat-headed peccary, caribou, giant beaver and other animals, according to Redmond and Tankersley's 2005 paper in American Antiquity. One bone point is directly dated to about 12,800 calendar years ago. Flat-headed peccary is the site's commonest large animal, with dozens of individuals identified, and the site also produced giant short-faced bear, black bear and stag-moose. In all, the cave has yielded over 75 species of Ice Age animals, including — identified in 2021 from DNA in the root of a single incisor — Ohio's first and only known dire wolf, according to the Ohio History Connection.

The site has also drawn attention from proponents of the Younger Dryas Impact Hypothesis, the idea that a comet or asteroid impact around 12,800 years ago triggered a sudden cold snap and helped drive Ice Age megafauna extinct. A 2014 chronological review found that the charcoal layer cited as evidence at the Wyandot County site is measurably younger than the sediment layer it sits in, a problem the reviewers could not reconcile, and that only 3 of the 29 sites offered in support of the hypothesis actually date to the proposed event. Wider critiques point to the lack of any confirmed impact crater and failed attempts to replicate the physical evidence; most specialists reject the hypothesis, though a group of proponents continues to publish in its favor, according to Wikipedia's entry on the Younger Dryas impact hypothesis.

Ground sloths, stag-moose and a mystery predator

Ohio's ground sloth record centers on two specimens that are often confused, and shouldn't be. "Jeff," now mounted at Ohio State University's Orton Geological Museum, was first uncovered by workers digging a drainage ditch on a Holmes County farm near Millersburg in late 1890 — the first substantial skeletal remains of the species Megalonyx jeffersonii ever found, and the first mounted skeleton of that species anywhere, on display since 1896. The genus is named for Thomas Jefferson, who presented it to the American Philosophical Society in 1797 after first mistaking claw and limb bones from western Virginia for those of a giant clawed carnivore. A claw from Jeff's skeleton was dated in 2015 to roughly 13,100 calendar years ago, the youngest radiocarbon age determined for the species at that time, according to a study in Quaternary Research. Jeff shows no evidence of butchery.

The cut marks belong to a different animal: the Firelands ground sloth, ten bones found in a swamp in Huron County before 1915 and kept at a historical society museum in Norwalk. Scanning-electron-microscope analysis of the left femur documented 41 stone-tool marks placed as if filleting the leg muscles, and the bone dated to roughly 13,600 calendar years ago — as much as 700 years older than the calculated maximum age for the Clovis culture, according to Redmond and colleagues' 2012 paper in World Archaeology. The authors note that the bones' lack of clear original context weakens the case for a confirmed kill site.

Stag-moose (Cervalces scotti) were known from only 11 Ohio finds as of 2010. The best-recorded is an accidental 2008 discovery near Chippewa Lake in Medina County: a landowner digging clay to line a horse-riding rink had a backhoe operator bring up a partial skull and large antler fragments from 16 feet down in lake clay; Ohio Historical Society staff recovered 44 bones and fragments in a follow-up dig. Several leg bones showed spiral fractures — a break pattern that can only occur while bone is still fresh — plus large conical tooth punctures consistent with a big carnivore's bite. As of the source article's 2010 writing, staff had compared the marks against wolf-kill moose bones from a long-running wolf study and feeding tests with zoo bears and cougars, and preliminary results suggested neither wolves nor the bear species tested were a likely match, leaving the actual predator an open mystery, according to the Ohio History Connection.

When the last ones died

Bison survived in Ohio into the historic era. An estimated 30 to 70 million bison once lived in North America; decades of over-hunting and habitat loss as settlers arrived pushed them out of the Ohio Country, and the last wild bison in Ohio was shot and killed in Lawrence County in 1803, the year Ohio became a state, according to the Ohio History Connection. Small reintroduced herds now live at a few Ohio parks and zoos, including a herd of eight Plains bison at Battelle Darby Creek Metro Park, relocated there in 2011.

Two of Ohio's most quotable extinctions bookend the deeper Ice Age story as epilogues. Martha, the last known passenger pigeon, died at the Cincinnati Zoo at 1 p.m. on September 1, 1914, aged about 29 — the extinction of a species once the most numerous bird in North America, according to Wikipedia). Incas, the last known Carolina parakeet, died at the Cincinnati Zoo on February 21, 1918, reportedly in the same enclosure where Martha had died. The zoo dedicated a Passenger Pigeon Memorial in 1974.

The extinction event that looms over this whole chapter — the North American megafaunal collapse of roughly 13,000 to 11,000 years ago — remains one of the most argued questions in the field. During the Late Pleistocene, about 65 percent of the world's megafaunal species went extinct; in North America the figure was about 72 percent, and every mammal over 1,000 kilograms vanished from the Americas, according to Wikipedia's entry on the Quaternary extinction event. The two leading explanations are the "overkill" model, in which newly arrived human hunters drove naive, slow-reproducing megafauna to extinction in a fast wave, and climate and habitat change, in which the end of the Ice Age collapsed the mixed tundra-parkland environment these species depended on. Most researchers today support at least a contributory human role, but the debate over how much weight each factor carried remains unresolved. Ohio's own evidence sits squarely inside that argument: the Burning Tree Mastodon's disputed cut marks and the Firelands ground sloth's stone-tool-scarred femur are exactly the kind of site-level evidence the debate depends on, case by case.

The clearest anchor for the human side of this story sits just across the Ohio River, at Big Bone Lick, a mineral spring and salt lick in Boone County, Kentucky, that trapped and preserved huge numbers of Ice Age mammals. Meriwether Lewis made a side trip there in 1803 on his way to join William Clark, collecting fossils for President Thomas Jefferson; the shipment sank in the Mississippi. In September 1807, Jefferson funded Clark to lead the first formal excavation for fossils there — "now recognized as the beginning of the science of vertebrate paleontology in America," according to the Cincinnati Museum Center. A ten-man crew spent several weeks and recovered some 300 bones and teeth, helping naturalists of the era begin to tell mammoth from mastodon remains for the first time.

Sources

• Michael Hansen, "Bestiary of Pleistocene Vertebrates of Ohio," ODNR Ohio Geology, Winter 1992
• Wikipedia, "Burning Tree Mastodon"
• Rhodes et al. 1998, Applied and Environmental Microbiology, via PMC
• Lothrop et al. 2016, PaleoAmerica
• Cleveland Museum of Natural History, "The Johnstown Mastodon Turns 100"
• Ohio History Connection, "How to Find a Mastodon"
• Ohio History Connection, "That's One Huge Rodent!"
• Redmond and Tankersley 2005, American Antiquity
• Ohio History Connection, "It's About Time: A New Ice Age Carnivore Found in Ohio," 2021
• Meltzer et al. 2014, PNAS, via PMC
• Wikipedia, "Younger Dryas impact hypothesis"
• Orton Geological Museum, Ohio State University, "History of Jeff the Giant Ground Sloth"
• McDonald, Stafford and Gnidovec 2015, Quaternary Research
• Redmond et al. 2012, World Archaeology
• Ohio History Connection, "Natural History Mystery: Of Wolves, Moose and Old Bones"
• Ohio History Connection, "Bye-Son: The Extirpation and Reintroduction of the Bison in the Ohio Country," 2018
• Wikipedia, "Martha (passenger pigeon)")
• Wikipedia, "Incas (parakeet)")
• Wikipedia, "Quaternary extinction event"
• Cincinnati Museum Center, "Thomas Jefferson and the Mastodon"