American paleontologists trailed Europeans in emphasizing theory, focusing instead on collecting, cataloging, and describing fossil materials. A bitter feud developed in the 1870s between the paleontologists Othniel Charles Marsh and Edward Dinker Cope, who repeatedly accused one another of stealing fossil specimens and of professional ineptitude. The feud lasted into the 1890s. A letter from Cope to Marsh is typical of the exchanges that occurred during this dispute:

I wish you had mentioned to me about missing specimens from Kansas, Wyoming etc. When the first suspicion crossed your mind that I knew anything about them. It is far more irritating to me to be charged with dishonorable acts than to lose material, species etc.

I never knew of any losses sustained by you, or specimens taken by any one, till those were sent me that you now have. Should any such...