MEMOIRS OF THE PEABODY MUSEUM OF YALE COLLEGE

VOL.  I

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ODONTORNITHES:

A

MONOGRAPH

ON THE

EXTINCT TOOTHED BIRDS OF NORTH AMERICA

WITH THIRTY-FOUR PLATES AND FORTY WOODCUTS

BY

OTHNIEL CHARLES MARSH

Professor of Palæontology in Yale College

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NEW HAVEN, CONN.

PRINTED FOR THE MUSEUM.

 1880

INTRODUCTION.

             The remains of Birds are among the rarest of fossils, and very few have been discovered except in the more recent formations. According to present evidence, the oldest known Birds were imbedded in the Jurassic deposits of Europe, which have yielded three individuals belonging to the genus Archaeopteryx, so well preserved that the more important characters can be determined. The only other remains of birds found in the Mesozoic of the Old World are a few specimens from the Cretaceous of England, which are too fragmentary to throw much light on the extinct forms they represent.

             The earliest traces of Birds hitherto found in the strata of this country are from the Cretaceous, although we may confidently predict their discovery in the Jurassic beds, if not at a still lower horizon. There is at present no evidence whatever that any of the three-toed impressions in the Triassic, described as the footprints of Birds, were made by Birds; and the proof now seems conclusive that nearly all of them are the tracks of Dinosaurian reptiles, bones of which occur in the same deposits. In the Cretaceous beds of the Atlantic Coast, and especially in the green-sand region of New Jersey, various remains of Birds have been found, and described by the writer^l. These fossils, although often in excellent preservation, occur mainly as isolated bones, and hence their near affinities have not as yet been determined with certainty.

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 ¹See Synopsis at the end of this volume.

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2                                                                                                    ODONTORNITHES.

             Along the eastern slope of the Rocky Mountains, and especially on the adjoining plains in Kansas and Colorado, there is a series of Cretaceous strata remarkably rich in vertebrate fossils. The deposits are all marine, and, away from the mountains, they lie nearly horizontal. They have suffered much from erosion, and are still wasting away, especially along the river valleys. These beds consist mainly of a fine yellow chalk and calcareous shale, both admirably adapted to preserve delicate specimens, and here have been found the extinct Birds which form the subject of the present memoir.

            The geological horizon of the known Odontornithes is in the Middle Cretaceous, and corresponds to the strata named by the writer the "Pteranodon beds." The latter are included in sub-division number three, in Meek and Hayden's section. The accompanying fossils are Mosasauroid reptiles, which are very abundant; Plesiosaurs, allied to Pliosaurus; Pterodactyles, of the genus Pteranodon; and many Fishes. With these occur Rudistes, and occasionally Ammonites, Belemnites, and various other Cretaceous invertebrates.

            The first Bird fossil discovered in this region was the lower end of the tibia of Hesperornis, found by the writer in December, 1870, near the Smoky· Hill River in Western Kansas. Specimens belonging to another genus of the Odontornithes, were discovered on the same expedition. The extreme cold, and danger from hostile Indians, rendered a careful exploration at that time impossible.

            In June of the following year, the writer again visited the same region, with a larger party, and a stronger escort of United States troops, and was rewarded by the discovery of the skeleton which forms the type of Hesperornis regalis, Marsh. Various other remains of Odontornithes were secured, and have since been described by the writer. Although the fossils obtained during two months of exploration were important, the results of this trip did not equal our expectations, owing in part to the extreme heat (1100 to 1200 Fahrenheit, in the shade) which, causing sunstroke and fever, weakened and discouraged guides and explorers alike.

                                                                                                       INTRODUCTION.                                                                                        3

             A considerable part of these Cretaceous deposits still remained unexplored, and in the autumn of 1872, a third expedition through this territory was undertaken by the writer, with a small party. Additional specimens  of much interest were secured, including the type of the genus Apatornis, and one nearly complete skeleton of Hesperornis, an ample reward for the hardship and danger we incurred.

            The specimens thus secured by these various expeditions have since been supplemented by important additions, collected in the same general region· by different parties equipped and sent out by the writer, who no longer could give his personal supervision to work in that field. The fossil Birds procured in this region since 1870, by these different expeditions, include remains of more than one hundred different individuals of the Odontornithes. These are all in the Museum of Yale College, and form. the material on which the present volume is based.

            A study of this extensive series of Bird remains brings to light the existence in this class of two widely separated types, which lived together during the Cretaceous period, in the same region, and yet differed more . from each other than do any two recent birds. Both of these types possessed teeth, a character hitherto unknown in the class of Birds, and hence they have been placed by the' writer in a separate sub-class, the Odontornithes. One of these groups includes very large swimming birds, without wings, and with the teeth in grooves (Odontonithes), and is represented by the genus Hesperornis. The other contains small birds, endowed with great powers of flight, and having teeth in sockets (Odontornithes), and biconcave vertebrae; a type best illustrated by the genus Ichthyornis.

            Other characters, scarcely less important, appear in each group, and we have thus a vivid picture of two primitive forms of bird structure, as unexpected as they are suggestive. A comparison of these two forms with each other, and with some recent birds, promises to clear away many difficulties in the genealogy of this class, now a closed type; and hence they are well worthy of the detailed description and full illustration here devoted to them.

4                                                                                                       ODONTORNITHES.

             The fossil birds now known from the Cretaceous deposits of this country are included in nine genera, and twenty species. These have all been described by the writer, and are represented, at present, by the remains of about one hundred and fifty different individuals. This is evidence of a rich and varied avian fauna in America during Mesozoic time, and likewise indicates what we may expect from future discoveries.