 Though Cope's scientific pursuits nearly bankrupted him, his contributions helped to define the field of American paleontology. He was a prodigious writer, with 1,400 papers published over his lifetime, although his rivals debated the accuracy of his rapidly published works. He discovered, described, and named more than 1,000 vertebrate species, including hundreds of fishes and dozens of dinosaurs. His proposal for the origin of mammalian molars is notable among his theoretical contributions. "Cope's rule", however, the hypothesis that mammalian lineages gradually grow larger over geologic time, while named after him, is "neither explicit nor implicit" in his work.
