Why did two rival scientists smash dinosaur bones to beat each other?

To keep fossils out of each other's hands. Edward Drinker Cope of Philadelphia and Othniel Charles Marsh of Yale fought the Bone Wars, a ruthlessly competitive fossil hunt in the American Gilded Age, and they would destroy smaller or damaged fossils rather than let them fall into the rival's hands. From 1877 to 1892 each financed his own expeditions and bought bones from fossil hunters, and each used underhanded methods: bribery, theft, and the destruction of bones.

It began amicably. After a fossil-collecting trip to Cope's marl pits in New Jersey, the two parted on good terms, but Marsh secretly bribed the pit operators to send future finds to him instead of Cope. Marsh also humiliated Cope by pointing out that his reconstruction of the plesiosaur Elasmosaurus had the head where the tail should have been, and Cope tried to hide the error by buying up every copy of the journal he could find.

The digging turned dirty. The two men filled in their own excavations with dirt and rock to protect them, and their discoveries came with sensational accusations of spying, stealing workers and fossils, and bribery. The feud went public when the New York Herald ran a story headlined 'Scientists Wage Bitter Warfare'. Both men ended up out of money.

Yet the science was real too. Their efforts led to 142 new species of dinosaurs being discovered and described; before them, only nine dinosaur species had been named in North America. Triceratops, Allosaurus, Diplodocus and Stegosaurus are among them.