The Jurassic formation on the Atlantic coast. Supplement / by O.C. Marsh.

  • Marsh, Othniel Charles, 1831-1899.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: The Jurassic formation on the Atlantic coast. Supplement / by O.C. Marsh. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Foi example, at tlie time tlie above work was ])ub]islied one fi’iiitfnl liorizons of vertebrate fossils over discov- ered had been known for several years in the Jurassic of the West. Many tons of gigantic fossil vertebrates had been col- iGctcd iioin SGVGiftl loCcilitics, und tliG principtil forms dGScribGd and hguied, while the illustrations had been reproduced even in text-books. Moreover, the Jurassic horizon in which these and other remains were found had been definitely determined and named the Atlantosaurus beds, and a geological section showing their position and characteristic genera had been pub- lished several times. The fossils thus discovered embraced mammals, birds, reptiles, and fishes, nearly all of well-marked Jurassic types. Since 1880, when the statement I have quoted was made, other discoveries have followed in rapid succession, and the Jurassic vertebrate fauna of the West is now known to be a most rich and varied one, far in advance of that from any other part of the world. More than one hundred and fifty species of extinct vertebrates, some of them represented by hundreds of specimens, have been brought to light, and over one hundred of these have already been described, and the more important have been refigured and republished in various parts of the world, including text-books, so that anyone with even an elementary knowledge of the subject can see that they are Jurassic in type. Nevertheless, a number of American geologists whose studies have kept them in other fields still appear to be ignorant of nearly all that has been made known about vertebrate paleontology in this country during the last quarter of a century, and seem to think that the Jurassic formation here is of small importance, and that its area should be restricted rather than enlarged. Another of my reviewers was G. K. Gilbert, editor of the work from which I have just quoted. Whether he intended his remarks on my paper to be taken seriously is not clear. Apparently he wished to start an academic discussion on correla- tion, and under the circumstances this would probably have led from the E,ocky Mountains to the Mountains of the Moon, one of his latest fields of investigation. If he is really in doubt about the methods of correlation of vertebrate fossils, he can perhaps find the information he needs in text-books. First of all, however, I must question the accuracy of some of the statements in his review of my paper. One of these is as follows: “ Through a comparison of vertebrates from the Potomac forma- tion with vertebrates from other formations he has inferred the Jurassic age of the Potomac; but he gives no hint of the charac- ter of his evidence or the course of his reasoning.”* * Science, vol. iv, p. 876, 1896.