to write him, unaware of his death until 1870. The circumstances around Turner's discovery of the type specimen were not covered in Cope's report, and remained unknown until Turner's letters were published in 1987. Elasmosaurus was the first major fossil discovery in Kansas (and the largest from there at the time), and marked the beginning of a fossil collecting rush that sent thousands of fossils from Kansas to prominent museums on the American east coast. Elasmosaurus was one of few plesiosaurs known from the New World at the time, and the first recognized member of the long-necked family of plesiosaurs, the Elasmosauridae. In 1869 Cope scientifically described and figured Elasmosaurus, and the preprint version of the manuscript contained a reconstruction of the skeleton which he had earlier presented during his report at an ANSP meeting in September 1868. The reconstruction showed Elasmosaurus with a short neck and a long tail, unlike other plesiosaurs, and Cope was also unsure whether it had hind limbs. At an ANSP meeting a year and a half later, in March 1870, the American paleontologist Joseph Leidy (Cope's mentor) noted that Cope's reconstruction of Elasmosaurus showed the skull at the wrong end of the vertebral column, at the end of the tail instead of the neck. Cope had apparently concluded that the tail vertebrae belonged to the neck, since the jaws had been found at that end of the skeleton, even though the opposite end terminated in the axis and atlas bones that are found in the neck. Leidy also concluded that Elasmosaurus was identical to Discosaurus, a plesiosaur he had named in 1851. To hide his mistake, Cope attempted to recall all copies of the preprint article, and printed a corrected version with a new skeletal reconstruction that placed the head on the neck (though it reversed the orientation of the individual vertebrae) and different wording in 1870. In a reply to Leidy, Cope claimed that he had been misled by the fact that Leidy had arranged the vertebrae of Cimoliasaurus in the reverse order in his 1851 description of that genus, and pointed out that his reconstruction had been corrected. Cope also rejected the idea that Elasmosaurus and Discosaurus were identical, and noted that the latter and Cimoliasaurus did not have any distinguishing features. Though Cope had tried to destroy the preprints, one copy came to the attention of the American paleontologist Othniel Charles