Originally colleagues who were civil to each other, Cope and Marsh became bitter enemies after several personal slights between them. Their pursuit of bones led them west to rich bone beds in Colorado, Nebraska, and Wyoming. From 1877 to 1892, both paleontologists used their wealth and influence to finance their own expeditions and to procure services and fossils from dinosaur hunters. By the end of the Bone Wars, both men exhausted their funds in fueling their intense rivalry.
Cope and Marsh were financially and socially ruined by their efforts to disgrace each other, but their contributions to science and the field of paleontology were massive; the scientists left behind tons of unopened boxes of fossils on their deaths. The feud between the two men led to over 142 new species of dinosaurs being discovered and described. The products of the Bone Wars resulted in an increase in knowledge of ancient life, and sparked the public's interest in dinosaurs, leading to continued fossil excavation in North America in the decades to come. Several historical books and fictional adaptations have also been published about this period of intense paleontological activity.
Cope and Marsh came from very different backgrounds. Cope was born into a wealthy and influential Quaker family based in Philadelphia. Although his father wanted his son to work as a farmer, Cope instead distinguished himself as a naturalist. In 1864, Cope became a professor of zoology at Haverford College and joined Ferdinand Hayden on his expeditions west. Marsh would have grown up poor, the son of a struggling family in Lockport, New York, had it not been for the benefaction of his uncle, philanthropist George Peabody. Marsh persuaded his uncle to build the Peabody Museum of Natural History, placing Marsh as head of the museum. Combined with the inheritance he received from Peabody upon his death in 1869, Marsh was financially comfortable (although due in part to Peabody's stern views on marriage, Marsh would remain a lifelong bachelor.)
On one occasion, the two scientists had gone on a fossil-collecting expedition to Cope's marl pits in New Jersey, where William Parker Foulke had discovered the holotype specimen of Hadrosaurus foulkii, described by the paleontologist Joseph Leidy; this was one of the first American dinosaur finds, and the pits were still rich with fossils. Though the two parted amicably, Marsh secretly bribed the pit operators to divert the fossils they were discovering to him, instead of Cope. The two began attacking each other in papers and publications, and their personal relations soured. Marsh humiliated Cope by pointing out his reconstruction of the plesiosaur Elasmosaurus was flawed, with the head placed where the tail should have been. Cope, in turn, began collecting in what Marsh considered his private bone-hunting turf in Kansas and in Wyoming. Any pretense of cordiality between the two ended in 1872, and open hostility ensued.
When Marsh responded to Lakes, he paid the prospector $100, urging him to keep the finds a secret. Learning that Lakes had corresponded with Cope, Marsh sent his field collector Benjamin Mudge to Morrison to secure Lake's services. At the same time Marsh published a description of Lake's discoveries in the American Journal of Science on July 1, and before Cope could publish his own interpretation of the finds, Lakes wrote to him that the bones should be shipped to Marsh, a severe insult to Cope.
A second letter arrived from the West, this time addressed to Cope. O.W. Lucas was a naturalist who had been collecting plants near Cañon City, Colorado, when he came upon an assortment of fossil bones. After receiving more samples from Lucas, Cope concluded the dinosaurs were large herbivores, gleefully noting the specimen was larger than any other described at the time, including Lakes' discovery. Marsh heard of Lucas' finds and instructed Mudge and his former student Samuel Wendell Williston to set up a quarry on his behalf near Cañon. Unfortunately for Marsh, he learned from Williston that Lucas was finding the best bones and had refused to quit Cope to work for him. Marsh ordered Williston back to Morrison, where Marsh's small quarry collapsed and nearly killed his assistants. This setback would have dried up Marsh's bone supply from the west if not for a third letter addressed to him.
At the time of Lake's discoveries, the Transcontinental Railroad was being built through a remote area of Wyoming. Marsh's letter was from two men identifying themselves as Harlow and Edwards (their real names were Carlin and Reed), workers on the Union Pacific Railroad. The two men claimed they had found large amounts of fossils in Como Bluff, and warned that there were others in the area "looking for such things", which Marsh took to mean Cope. Marsh sent Williston, who had just wearily arrived in Kansas after the collapse of the Morrison mine, to Como. His former student sent back a message, confirming the veracity of both the large quantities of bones and the reports that Cope's men were snooping around in the area. Wary of repeating the same mistakes he had made with Lakes, Marsh quickly sent money to the two new bone hunters and urged them to send additional fossils. Williston struck a preliminary bargain with Carlin and Reed (who had been unable to cash Marsh's check due to it being made out to their pseudonyms), but Carlin decided he would head to New Haven to deal with Marsh directly. Marsh drew up a contract calling for a set monthly fee, with additional cash bonuses to Carlin and Reed possible, depending on the importance of the finds. Marsh also reserved the right to send his own "superintendents" to supervise the digging if needed, and advised the men to try and keep Cope out of the region. Despite a face-to-face meeting, Carlin failed to negotiate better terms from Marsh. The paleontologist procured Carlin's and Reed's work for the stated terms, but seeds of discord and resentment were sown in the bone hunters as they felt Marsh had bullied them into the deal. Marsh's investment in the Como Bluff region soon produced rich results. While Marsh's own collectors headed east for the winter, Reed sent carloads of bones by rail to Marsh throughout 1877. Marsh described and named dinosaurs such as Stegosaurus, Allosaurus, and Diplodicus in the December 1877 issue of the American Journal of Science.
Despite Marsh's precautions against alerting his rival to Como Bluff's rich bone beds, word of the discoveries quickly spread. Carlin and Reed were involved in the spreading of these rumors, leaking information to the Laramie Daily Sentinel which published an article about the finds in April 1878. The piece exaggerated the price Marsh had paid for the bones heading east, possibly to raise prices and demand for more bones. Marsh, attempting to cover the leak, learned from Williston that Carlin and Reed had been frequented by a man ostensibly working for Cope by the name of "Haines". Cope had learned of the Como Bluff discoveries, and sent "dinosaur rustlers" to the area in an attempt to quietly steal fossils from under Marsh's nose. During the winter of 1878 dissatisfaction with Marsh's infrequent payments fomented, and Carlin began working for Cope instead.
Cope and Marsh used their personal wealth to fund expeditions each summer, then spent the winter publishing their discoveries. Small armies of fossil hunters in mule-drawn wagons or on trains were soon sending literal tons of fossils back east. Marsh's teams were the more extravagant; he had crews of at least five workers assist him on the occasions he went West himself. Cope, on the other hand, made do with two teamsters, a cook, and a guide. The paleontological digs lasted fifteen years, from 1877 to 1892. The workers for both Cope and Marsh suffered hardships related to the weather, as well as sabotage and obstruction by the other scientist's workers. Reed was locked out of the Como train station by Carlin and was forced to haul the bones down the bluff and crate the specimens on the train platform in the bitter cold. Cope directed Carlin to set up his own quarry in Como Bluff, while Marsh sent Reed to spy on his former friend. As Reed's Quarry #4 dried up, Marsh ordered Reed to clear out the bone fragments from the other quarries. Reed reported he had destroyed all the remaining bones to keep them away from Cope. Concerned that strangers were encroaching on Reed's quarries, Marsh sent Lakes to Como to assist in excavations, and in June 1879 visited Como himself. Cope likewise toured his own quarries in August. Although Marsh's men continued to open new quarries and discover more fossils, relations between Lakes and Reed soured, with each offering his resignation in August. Marsh attempted to placate the two by sending each to opposite ends of the quarries, but after being forced to abandon one bone quarry in a freezing blizzard, Lakes submitted his resignation and returned to teaching in 1880. The departure of Lakes did not ease tensions among Marsh's men; Lake's replacement, a railroad man named Kennedy, felt he didn't have to report to Reed, and the fighting between the two caused Marsh's other workers to quit. Marsh tried separating Kennedy and Reed, and sent Williston's brother Frank to Como in an effort to keep the peace. Frank Williston ended up leaving Marsh's employ and taking up residence with Carlin. Cope's own digging in Como began faltering, and Carlin's replacements soon quit work altogether.
As the 1880s progressed, Cope's and Marsh's men faced stiff competition from each other and third parties interested in bones. Professor Alexander Emanuel Agassiz of Harvard sent his own representatives west, while Carlin and Frank Williston formed a bone company to sell fossils to the highest bidder. Reed left and began a career in sheep herding in 1884, and Marsh's Como quarries yielded little after his departure. Despite these setbacks, Marsh had more operational quarries than Cope at this point of time; Cope, who at the early 1880s had more bones than he could fit in a single house, had fallen behind in the race for dinosaurs.
Cope's and Marsh's discoveries were accompanied by sensational accusations of spying, stealing workers and fossils, and bribery. The two men were so protective of their digging sites that they would destroy smaller or damaged fossils to prevent them from falling into their rival's hands, or fill in their excavations with dirt and rock; while surveying his Como quarries in 1879, Marsh examined recent finds and marked several for destruction. On one occasion the scientist's rival teams fought each other by throwing stones.
By the late 1880s, public attention to the fighting between Cope and Marsh faded, drawn to international stories rather than the "Wild West". Thanks to John Wesley Powell, head of the U.S. Geological Survey, and Marsh's contacts with the rich and powerful in Washington, Marsh was placed at the head of the consolidated government survey and was happy to be out of the sensationalist spotlight. Cope was much less well-off, having spent most of his money purchasing The American Naturalist, and had a hard time finding employment (due in part to his temperament as well as Marsh's allies in higher education.) Cope began investing in gold and silver prospects in the West, and braved malarial mosquitos and harsh weather to search for fossils himself. Due to setbacks in mining and a lack of support from the federal government, Cope's financial situation steadily deteriorated, to the point that his fossil collection was his only significant asset. Marsh, meanwhile, alienated even his loyal assistants, including Williston, with his refusal to share his conclusions drawn from their findings, and his continually lax and infrequent payment schedule.
Cope's chance to exploit Marsh's vulnerabilities came in 1884, when Congress began to investigate the proceedings of the consolidated geological survey. Cope had become friends with Henry Fairfield Osborn, then a professor of anatomy at Princeton University. Osborn was like Marsh in many ways, slow and methodical, but would prove a damaging influence on Marsh. Cope searched for disgruntled workers who would speak out against Powell and the Survey. For the moment, Powell and Marsh were able to successfully refute Cope's charges, and his allegations did not reach the mainstream press. Osborn seemed reluctant to step up his campaign against Marsh, so Cope turned to another ally he had mentioned to Osborn—a "newspaper man from New York" named William Hosea Ballou. Despite setbacks in trying to oust Marsh from his presidency of the National Academy of Sciences, Cope received a tremendous financial boost after the University of Pennsylvania offered him a teaching job. Soon after, Cope's chance to strike a critical blow at Marsh appeared.
Over the years, Cope kept an elaborate journal of mistakes and misdeeds that Marsh and Powell had committed; the mistakes and errors of the men were put in writing and ensconced in the bottom drawer of Cope's desk. Ballou planned the first set of articles, in what would become a series of newspaper debates between Marsh, Powell and Cope. While the scientific community had long known of Marsh and Cope's rivalry, the public became aware of the shameful conduct of the two men when the New York Herald published a story with the headline "Scientists Wage Bitter Warfare." According to author Elizabeth Noble Shor, the scientific community was galvanized:
Most scientists of the day recoiled in horror—and read on with interest, to find that Cope's feud with Marsh had at last become front-page news. Those closest to the scientific fields under discussion, geology and vertebrate paleontology, certainly winced, particularly as they found themselves quoted, mentioned, or misspelled. The feud was not news to them, for it had lurked at their scientific meetings for two decades. Most of them had already taken sides.
In the newspaper articles, Cope attacked Marsh for plagiarism and financial mismanagement and attacked Powell for his geological classification errors and misspending of government allocated funds. Marsh and Powell were each able to publish their own side of the story, filing their own charges against Cope. Ballou's articles were poorly researched, written, and read, and Cope himself was smarting from a Philadelphia Inquirer piece which suggested the University of Pennsylvania trustees would ask Cope to step down unless he provided proof for his charges against Marsh and Powell. Marsh himself kept the Herald story alive with a fiery rebuttal, but by the end of January the story had faded from all the newspapers, and little changed between the bitter rivals.
No congressional hearing was created to investigate the misallocation of funds by Powell and neither Cope nor Marsh was held responsible for any of their mistakes, but some of Ballou's slander against Marsh came to be associated with the Survey. Facing anti-Survey sentiment inflamed by western drought and concerns about takeovers of abandoned western homesteads, Powell found himself the subject of larger scrutiny before the House Appropriations Committee. Galvanized to action by Marsh's perceived extravagance with Survey funds, the Appropriations Committee demanded the Survey's budget be itemized. When his appropriation was cut off in 1892, Powell sent a terse telegram to Marsh that he expected Marsh's resignation, a personal slight as well as a financial one. At the same time, many of Marsh's allies were retiring or had died, lessening his scientific credence. Just as Marsh's extravagant lifestyle was catching up with him, Cope received a position on the Texas Geological survey, although Cope, still reeling from the personal attacks levied at him during the Herald affair, did not press his personal attacks. Cope's fortunes continued to look up throughout the early 1890s, as Cope was promoted to Leidy's position as Professor of Zoology and was elected as the president of the National Association for the Advancement of Science the same year Marsh stepped down from the head of the Academy of Sciences. Towards the latter part of the decade, however, Cope's fortunes began to sour once more as Marsh regained some of his recognition, earning the Cuvier Medal, the highest paleontological award.
Cope and Marsh's rivalry lasted until Cope's death in 1897, by which time both men had been financially ruined. Cope suffered from debilitating illness in his later years and had to sell part of his fossil collection and rent out one of his homes to make ends meet. Marsh in turn had to mortgage his residence and ask Yale for a salary to live on. The rivalry between the two, however, remained strong if weary. Cope issued a final challenge before his death. He had his skull donated to science so that his brain could be measured, hoping that his brain would be larger than that of his adversary; at the time, it was thought brain size was the true measure of intelligence. Marsh never accepted the challenge, and Cope's skull is reportedly still preserved at the University of Pennsylvania. (Whether the skull stored at the University is Cope's is disputed; the University stated that it believes the real skull was lost in the 1970s, although Robert Bakker has said that hairline fractures on the skull and coroner's reports verify the skull's authenticity.)
Judging by pure numbers, Marsh "won" the Bone Wars. Both scientists made finds of incredible scientific value, but while Marsh discovered a total of 80 new dinosaur species, Cope discovered only 56. In the later stages of the Bone Wars, Marsh simply had more men and money at his disposal than Cope. Cope also had a much broader set of paleontological interests, while Marsh almost exclusively pursued fossilized reptiles and mammals.
Several of Cope's and Marsh's discoveries are the most well-known of dinosaurs, encompassing species of Triceratops, Allosaurus, Diplodocus, Stegosaurus, Camarasaurus and Coelophysis. Their cumulative discoveries defined the then-nascent field of paleontology; before Cope's and Marsh's discoveries, there were only nine named species of dinosaur in North America. Furthermore, some of their ideas—such as Marsh's argument that birds are descended from dinosaurs—have been upheld; while others, including "Cope's law", which states that over time species tend to get larger, are viewed as having little to no scientific merit. The Bone Wars also led to the discovery of the first complete skeletons, and the rise in popularity of dinosaurs with the public. As paleontologist Robert Bakker stated, "The dinosaurs that came from [Como Bluff] not only filled museums, they filled magazine articles, textbooks, they filled people's minds."
The Bone Wars had a negative impact not only on the two scientists but their peers and the entire field. The animosity and public behavior between Cope and Marsh harmed the reputation of American paleontology in Europe for decades. Furthermore, the reported use of dynamite and sabotage by employees of both men destroyed or buried hundreds of potentially critical fossil remains. Joseph Leidy abandoned his more methodical excavations in the West, finding he could not keep up with Cope's and Marsh's reckless searching for bones. In their haste to outdo each other, Cope and Marsh haphazardly assembled the bones of their own discoveries. Their descriptions of new species, based on their reconstructions, led to confusion and misconceptions that lasted for decades after their deaths.
A 2007–2008 excavation of several of Cope's and Marsh's sites suggest that some of the damage propagated by the two paleontologists was less than what has been recorded. Using Lakes' field paintings, researchers from the Morrison Natural History Museum discovered that Lakes had not actually dynamited the most productive quarries in Colorado; rather, Lakes had just filled in the site. Museum director Matthew Mossbrucker theorized that Lakes propagated the lie "because he didn't want the competition up at the quarry—playing mind games with Cope's gang.