A few years back, shortly after he introduced me to a splendid fossil alligator, Peabody Museum of Natural History collections manager Christopher Norris led me into a bright room piled high with fossils. I’d seen similar storehouses before. As per usual, the larger specimens were cradled in carefully-crafted plaster jackets on shelves while the smaller bones were safely locked in metal cabinets bearing scientific incantations such as “merycoidodontoidea” and “borhyaenidae“. But a series of lumpy skulls arranged along the left wall were what immediately grabbed my attention. These were the great dinoceratans that Yale's own O.C. Marsh fought so fiercely to defend from his chief rival.

I’m not sure why I’m so taken with Uintatherium and its relatives. Maybe it’s because poorly-made models of the beast were regularly included in the plastic peg bags stuffed with dinosaurs I picked up at the supermarket despite the fact that Uintatherium was a mammal and not a ruling reptile. Or perhaps it was The Last Dinosaur, in which a charging puppet Uintatherium is mistaken for a horned dinosaur. Then again, such mistakes might be a clue in themselves. Uintatherium and its relatives in the Dinocerata – the terrible horns – were some of the earliest large mammals after non-avian dinosaurs were ushered off the evolutionary stage, and the combination of the paired knobs on their skulls, long saber-teeth, and rhino-range size may make them look dinosaurish enough to stimulate the same parts of my brain that respond to images of Triceratops and Styracosaurus. What I didn’t learn until much later was how fiercely paleontologists had battled over these ancient mammals.

If you’ve had any exposure to the history of paleontology at all, you undoubtedly know the names Othniel Charles Marsh and Edward Drinker Cope. These late 19th century scientists waged the great “Bone Wars” against each other, each of them trying to outpace the other to become America’s chief expert on prehistoric life. The exact date and time the two started their “bitter warfare” is lost to history. A sensible starting point would be when Marsh paid one of Cope’s sources to funnel fossils to him in New Haven. Cope’s public embarrassment at putting the head of Elasmosaurus on the wrong end of the marine reptile didn’t help matters. But whatever initially sparked the acrimony that would run the length of both men’s lives, their publication record shows that the two chose Uintatherium and its ilk for their first major scientific showdown.

A Uintatherium skull at the Field Museum. Photo by Brian Switek

The fight for the Dinocerata started with Joseph Leidy. A Philadelphia polymath, Leidy was less fractious than Cope or Marsh but he nevertheless saw that the two of them – for better or worse – were about to set paleontology on fire. If Leidy was going to continue to leave his mark on paleontology, he’d have to move with speed to establish names and boundaries of scientific territory before Cope and Marsh swept in. So, before he even got home from a fossil collecting trip to Fort Bridger, Wyoming in 1872, Leidy wrote a brief description of two fossil mammals his party had found in the area. From a skull and limb bones, Leidy named Uintatherium robustum, and, not realizing that it belonged to the same animal, he used a tooth to establish another species called Uintamastrix taro.

Historian Keith Thomson recounts the conflict that followed in his book The Legacy of the Mastodon. Up until 1872, Leidy had become a de facto authority on many of America’s fossil mammals. Cope and Marsh occupied themselves with different sorts of prehistoric reptiles, fish, and fowl. Either intentionally or through other experts wishing not to get between the two, they had worked out a way to generally avoid each other. But the wealth of strange mammals flowing from the west brought Cope and Marsh into a vicious whirlwind of hasty descriptions and rushed taxonomy.

It made sense for Leidy, Cope, and Marsh to tussle over the Dinocerata. These were spectacular animals unlike any seen before or since. Naming them was a matter of control, and, for Cope and Marsh, whoever claimed them would simultaneously polish their reputation while tarnishing that of their sluggish rival. The telegraph seemed the perfect tool for the job. The same year that Leidy named Uintatherium, Cope sent a telegraph to the American Philosophical Society proclaiming that he had discovered three new species and one new genus of related animals.

Unfortunately for Cope, scientific minutiae don't translate well over telegraph. All the names came out garbled, and, as Thomson recounts, the secretary of the Society told his colleagues that the exact spelling of the names would have to wait until Cope returned. Meanwhile, Marsh was already trying a different technique. He added a note of publication dates to a monograph titled Preliminary Descriptions of New Tertiary Mammals, keeping track of when his pamphlets announcing new fossil names were distributed. Detailed description of these creatures was an afterthought. Establishing the name was the critical part.

Titles racked up fast. In addition to Leidy’s Uintatherium and Uintamastrix, Cope added Loxolophodon and Eobasileus while Marsh established Dinoceras and Tinoceras. (And that’s not even counting the multiple species being assigned to some of these.) But it was quickly becoming clear that these Eocene animals differed little, if at all, from each other. There were fewer genera and species than had been named, but who could rightly claim these creatures?

By rushing to name these fossils the scientists had created a monster out of ink, paper, and telegraph wire. The need to sort through the mess only offered a new opportunity for Cope and Marsh to turn the beasts against each other. Marsh was the first to try. In December of 1872, he ripped into Cope’s research and insisted that his names Dinoceras and Tinoceras were the right and proper names for all the “horned proboscideans” in question.

Cope shot back in April. Surprising no one, he insisted that his names – as well as Leidy’s Uintatherium – were right and Marsh’s were wrong, even though he grudgingly accepted Marsh’s suggestion of Dinocerata for the group’s name. Not one to let such insults go unanswered, Marsh continued his own campaign. It was a total trainwreck that their peers couldn’t look away from.

Then Marsh went a step beyond insisting that Cope’s science was shoddy. He attacked Cope’s claim to priority. If Marsh could prove that he properly published names for the fossils first, then Cope would be defenseless.

The telegraph was Cope’s weak point. Was Loxolophodon named when the first, misspelled telegraph was sent? When it was received? When a preliminary version of Cope’s paper was read? When the pamphlet of the report was received by all competing parties? When?! The American Philosophical Society held a meeting on the serious issue, but came to no resolution. The primary consequences, Thomson reports, were that Cope stopped trying to name species by telegraph and Marsh wrote a massive monograph on the Dinocerata in order to solidify his claim to the beasts, even though Leidy’s Uintatherium won out as the proper name for the slew of names that were in competition.

And what has become of the magnificent mammals that had America’s premiere paleontologists at each others’ throats? While  brontotheres, elephants, and other charismatic megafauna stepped into the spotlight, the Dinocerata faded into the background. Plastic toy sets still include them, and museums still display their skeletons – either the authentic fossils, or, often, as aged paper mache replicas – but the animals themselves have fallen into obscurity. The last major review of the Dinocerata was published in 1998, and little paleobiological work has been done to figure out how these unusual animals actually lived. There’s even some uncertainty about what sort of mammal they actually were. They’re problematica, possibly related to ungulates but perhaps not. 

Looking at the rows of skulls on the Yale shelves – the ones Marsh affectionately called “Dinoceras” and “Tinoceras” – I felt the not unfamiliar pang of regret for the academic path I abandoned. These fantastic skulls helped fuel one of the greatest fossil disputes of all time, and there they sat, waiting for someone to remember their meaning. In another life, perhaps I could’ve been one to revive them in the scientific imagination. As it was, I could only visit with them a while and wonder. And that’s why Uintatherium is still a favorite of mine. Not for what we know about it, but for what we have yet to discover.


Thomson, K. 2008. The Legacy of the Mastodon. New Haven: Yale University Press. pp. 215, 229-241.

[This piece was originally posted at National Geographic.]