Cope was born more directly into privilege—his father was a rich Philadelphia businessman—and was by far the more adventurous of the two. In the summer of 1876 in Montana while George Armstrong Custer and his troops were being cut down at Little Big Horn, Cope was out hunting for bones nearby. When it was pointed out to him that this was probably not the most prudent time to be taking treasures from Indian lands, Cope thought for a minute and decided to press on anyway. He was having too good a season. At one point he ran into a party of suspicious Crow Indians, but he managed to win them over by repeatedly taking out and replacing his false teeth.

柯普生于一个特权家庭——他的父亲是费城一位有钱的商人——比马什更富有冒险精神，1876年夏天，在蒙大拿州，当乔治·阿姆斯特朗·卡斯特和他的部队在小比格角被消灭的时候，柯普还在附近找骨头。有人提醒他，这时候来印第安人领地取宝，很可能是很不明智的。他想了片刻，决定继续往下干。他的收获太大了。有一次，他遇上了几个疑心重重的克劳族印第安人，但他不停地取下和装上他的假牙，赢得了他们的信任。

For a decade or so, Marsh and Cope's mutual dislike primarily took the form of quiet sniping, but in 1877 it erupted into grandiose dimensions. In that year a Colorado schoolteacher named Arthur Lakes found bones near Morrison while out hiking with a friend. Recognizing the bones as coming from a "gigantic saurian," Lakes thoughtfully dispatched some samples to both Marsh and Cope. A delighted Cope sent Lakes a hundred dollars for his trouble and asked him not to tell anyone of his discovery, especially Marsh. Confused, Lakes now asked Marsh to pass the bones on to Cope. Marsh did so, but it was an affront that he would never forget.

有10年左右的时间，马什和柯普之间的敌对关系主要以暗斗的形式出现，但到了1877年，暗斗突然变成了大规模的冲突。那年，一位名叫阿瑟·莱克斯的科罗拉多州小学老师和他的一位朋友出门徒步旅行，在莫里森附近发现了几根骨头。莱克斯认为那些骨头属于一条“巨蜥”；他想得很周到，把一些样品寄给了马什和柯普两个人。柯普很高兴，给莱克斯寄了100美元作为报酬，吩咐他不要把他的发现告诉任何人，尤其不要告诉马什。莱克斯不大明白，便请马什把骨头转交给柯普。马什这么做了，但遭到了一番他永生难忘的羞辱。