THE FOSSIL TURTLES OF NORTH AMERICA. 



ON THE SOURCES OF OUR KNOWLEDGE OF THE FOSSIL TURTLES OF 



NORTH AMERICA. 



The study of the fossil turtles of North America began in 1851, when Dr. 

 Joseph Leidy described, under the names Stylemys nebrascensis, Testudo lata, 

 Emys hemispherica, and Emys oweni, the extremely common fossil turtle of the 

 Oli^ocene Badlands of the present state of South Dakota, then a part of the Terri- 

 tory of Nebraska. It is true that in 1842 Dr. Richard Harlan had described and 

 figured (Amer. Jour. Sci., xliii, p. 144, pi. Ill, figs. 2, 3) as Cheloma coupcrt a bone 

 which he believed to be the femur of a large sea-turtle; but it is quite certain that 

 the bone was no part of any turtle. Dr. Leidy continued at intervals up to 1889 to 

 describe new species of fossil turtles. Most of Dr. Leidy's shorter papers appeared 

 in the Proceedings of the Philadelphia Academy, but his most important illustrated 

 works on the subject are found in D. D. Owen's Geological Survey of Wisconsin, 

 etc., 1852; in the sixth volume of the Smithsonian Contributions to Knowledge, 

 1854; and in the first volume of the monographs of Hayden's Geological Survey 

 of the Territories, 1872. Professor E. D. Cope began his publications of species 

 of fossil turtles in 1867; his last paper containing matter on the subject was pub- 

 lisht in 1899, after his death. His papers on the subject are numerous and will 

 be found cited in the writer's Bibliography and Catalogue of the Fossil Vertebrata 

 of North America, 1902. Cope's most important expositions of the turtles are to 

 be found in the fourteenth volume of the Transactions of the American Philosophical 

 Society, 1869 and 1870; in the second volume of the Hayden Survey monographs, 

 1875; in volume four of Wheeler's Survey West of the 100th Meridian, 1877; and 

 in the third volume of the monographs of the Hayden Survey, 1884. 



Professor O C. Marsh described only three species of fossil turtles. No new 

 fossil species are to be credited to Dr. George Baur, but he was the author of a 

 number of papers which made important additions to our knowledge of their 

 structure and relationships. Dr. S. W. Williston and Dr. E. C. Case have con- 

 tributed a number of valuable papers on the subject, especially on the turtles 

 derived from the Niobrara beds of Kansas. Dr. George R. Wieland has given 

 especial attention to the marine turtles of the Upper Cretaceous; and, especially, 

 he has described that remarkable cheloman monster Archelon ischyros. 



Other authors who have busied themselves more or less with the North American 

 chelonian population of past times are J. Z. Gilbert, L. M. Lambe of the 

 Canadian Geological Survey, Dr. F. B. Loomis, W. J. Sinclair, E. S. Riggs, and 

 O. P. Hav. The results of the studies of the authors mentioned are that more than 

 260 species of fossil turtles are now known from the geological deposits of North 

 America; the nearly complete structure of a considerable number of these has 

 been determined and much of that of others; and much light has been gained 

 regarding the history and relationships of the members of the order. Undoubtedly 

 many additional species will be discovered as the years pass away and species now- 

 known only from a few bones will become far better known. 



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