BIRDS.

BY S. W. WILLISTON.

     REMAINS of birds always have been and always will be the rarest of vertebrate fossils. From the habits of the great majority of species, together with the lightness and buoyancy of their bodies in the water, it is very evident that, even where they are abundant, they will not often fall into such positions that they will be fossilized. Although, with our present evidence, they first made their appearance in geological history as far back as the Jurassic formation, scarcely two score of valid species have thus far been discovered from the Mesozoic, and all of those, with one or two exceptions, are from the Upper Cretaceous formations.

     The famous Archaeopteryx, from the Jurassic of Solenhofen, the earliest bird known, has long been renowned for its strange mingling of reptilian and avian characters. With the wings imperfectly developed, there were long reptilian fingers with claws, adapted for seizing and grasping. The jaws were provided with well-developed teeth, and the tail was elongated as in reptiles, each individual vertebra provided with a pair of long feathers.

     The famous footprints of the Connecticut Triassic sandstone were, for a long time, supposed to have been made by birds. More recent discoveries of the remarkable reptiles known as Dinosaurs have shown that it was not only possible, but very probable, that all of them were made by these animals and none by birds.

     From the Lower Cretaceous no bird remains are yet known. From the Upper Cretaceous, aside from the footprints noticed below, the only remains yet known in America are from the Green Sand of New Jersey, the Niobrara Cretaceous of Kansas,

(43)

 44                    University of Kansas Geological Survey.

and the Fox Hills Cretaceous of Wyoming. Laopteryx, the supposed bird from the Jurassic of Wyoming, was founded upon very incomplete remains, and is, in all probability, not a bird, but a small Dinosaurian reptile.

     Twenty species of birds have been described from the American Cretaceous, the larger number of which are from the Kansas Cretaceous. Not a few of these are based upon very slight material, and it is not at all improbable that future fortunate discoveries will unite some of these and at the same time add new forms to the number already known.

     Bird remains, in Kansas, are, as elsewhere, among the rarest of the vertebrate fossils. One is likely to search weeks, and even months, without finding a single bone, even fragmentary. Among the thousands of specimens of vertebrates that have been collected in Kansas, not more than 175 of birds, of all kinds, have hitherto been discovered.

BIRDS OF THE NIOBRARA CRETACEOUS.

     The first specimens of birds known from Kansas were obtained by the expedition of Professor Marsh in 1870. In the following year a much more complete specimen of a Hesperornis was obtained by another expedition in charge of Professor Marsh, and, in 1872, still other specimens. By far the most important specimen of these early years, if not the most important of all those succeeding, as well as the one from which the discovery of the dentition was made, was one discovered by the late Professor Mudge, and sent by him to Professor Marsh. It was found by him near Sugar Bowl Mound, in northwestern Kansas, in 1872, and was first described by Marsh in October of that year under the name Ichthyornis dispar.

     An incident related to me by Professor Mudge in connection with this specimen is of interest. He had been sending his vertebrate fossils previously to Professor Cope for determination. Learning through Professor Dana that Professor Marsh, who as a boy had been an acquaintance of Professor Mudge, was interested in these fossils, he changed the address upon the box containing the bird

WILLISTON.]                        Birds.                                            45

specimen after he had made it ready to send to Professor Cope, and sent it instead to Professor Marsh. Had Professor Cope received the box, he would have been the first to make known to the world the discovery of "Birds with Teeth." (See Addenda to Part I.)

     During the succeeding years, the large collections of birds from this state were made for Professor Marsh by Mudge, Brous, Cooper, Guild, F. H. Williston, and the writer. Other bird remains have been obtained by Sternberg and Martin. In the University of Kansas museum there are portions of some twelve or more birds, including one specimen of a Hesperornis, much the most complete and perfect of any hitherto discovered. They apparently do not represent any new species or new forms, though not all agreeing with those described by Marsh.

     In the present paper it is not worth while entering into any detailed description of these forms, inasmuch as the very complete and richly illustrated monograph of Professor Marsh²⁶ must remain indispensable to all those who wish to obtain more complete information.

The following list includes all the known species of birds from the Kansas Cretaceous, based upon fossil remains:

RATITÆ - Odontolcæ.

Hesperornis.

Marsh, Amer. Journ. Sci., III, 56, Jan., 1872.

H. regalis Marsh, Amer. Journ. Sci., III, 56,1872.

     This species is the best known and the most common of all the species from the Kansas Cretaceous. Practically the complete skeleton is known. See pl. VI.

H. crassipes Marsh, Amer. Journ. Sci. XI, 509, June, 1876 (Lestornis).

     This species was discovered by Mr. G. P. Cooper, and collected by the present writer from the yellow chalk of Plum creek, in Gove County, Kansas. It is peculiarly characterized by the presence of a rugosity on the posterior outer side of the tarso-metatarsal, above

____________________________

26. Odontornithes; a Monograph of the Extinct Toothed Birds of North America. By Othniel Charles Marsh. New Haven and Washington, 1880. 

46                  University of Kansas Geological Survey.

its middle, as though for a spur. The specimen, which comprises a considerable portion of the skeleton, was first described as the type of the genus Lestornis. Marsh, later, thought that the roughening might be a sexual character.

H. gracilis Marsh, Amer. Journ. Sci., XI, 510,1876.

     This species, of smaller size than the preceding, is known from the nearly complete skeleton, according to Marsh, but has never been adequately described.

Baptornis.

Marsh, Amer. Journ. Sci., XIV, 86, July, 1877.

B. advenus Marsh, Amer. Journ. Sci., I. c., 1877.

     The type specimen, upon which this species and genus were based, was collected by a member of the writer's party in the yellow chalk. The generic difference is chiefly based upon the small size of the outer metatarsal.

CARINATÆ - Odontotormæ.

Ichthyornis.

Marsh, Amer. Journ. Sci., IV,  344, Oct., 1872.

I. dispar Marsh, l. c., 1872.

     The type specimen of this species was discovered, as already explained, by Mudge in 1872. It is, perhaps, the most complete specimen of this group that has ever been found, and the first of any known birds that showed the presence of teeth in the jaws. The teeth were first described as belonging to a reptile, by Marsh, in the Amer. Journ. Sci. for November, 1872, under the name Colonosaurus mudgei. The species is at present known from nearly the complete skeleton.

I. agilis Marsh, Amer. Journ. Sci., v, 230, 1873 (Graculavus).

     This species was based on very imperfect material discovered by Marsh in 1872, and has never yet been adequately described or figured, so that its determination, save by comparison with the type, will be more or less doubtful.

 WILLISTON .]                             Birds.                                      47

I. anceps Marsh, Amer. Journ. Sci., III, 364, May, 1872 (Graculavus).

     The type specimen, from the North Fork of the Smoky Hill river, has never been figured.

I. tener Marsh, Odontornithes, p. 198, 1880, pl. xxx, f. 8.

     Discovered by Mr. E. W. Guild, on the Smoky Hill river, in 1879.

I. validus Marsh, Odontornithes, p. 198, ff. 11, 14.

     Discovered by myself on the Solomon river, in 1877.

I. victor Marsh, Amer. Journ. Sci., xi, 511, June, 1876.

     The type specimen was discovered by Dr. H. A. Brous on the Smoky Hill river. Forty other specimens are referred by the author to the same species.

Apatornis.

Marsh, Amer. Journ. Sci. v, 162, Feb. 1872.

A. celer Marsh, Amer. Journ. Sci., v, 74, Jan. 1872 (Ichthyornis).

     The type specimen was discovered by Marsh in 1872. A more perfect specimen was found later by my brother, Mr. F. H. Williston, in 1877.

___________________

     The systematic position of the toothed birds from Kansas is by no means yet settled. All ornithologists are, however, agreed that they do not form a separate group, and the name Odontornithes is in consequence generally abandoned. The value of the teeth is subordinate; they do not in themselves justify a separate subclass.

     Hesperornis regalis, the best-known species of the genus, was a bird measuring about six feet from point of bill to the tip of the feet when outstretched, or standing about three feet high. It was an aquatic bird, covered with soft feathers, wholly wingless, the rudimentary wing bones doubtless being enclosed under the skin, and not at all effective in locomotion. The legs were strong and moderately long; the neck long and flexible. The bill was long, and was provided with small but effective conical teeth set in the jaw firmly. Those of the upper jaws were few in number and set in the back part, while those of the mandibles formed a complete series.

 48                   University of Kansas Geological Survey.

The jaws were united in front by cartilage only, permitting considerable mobility, which was doubtless very serviceable in swallowing their prey, which must have consisted of fishes caught by diving. The bones of the body were solid throughout, not hollow, as in almost all living birds. The sternum had no keel, as in the flying birds and those descended from flying birds, but was as in the ostrich. The vertebrae and skeleton, aside from the teeth, were not unlike those of modern birds, and, were the skull .yet unknown, would be unhesitatingly referred to the subclass to which the ostrich, cassowary and rhea belong. A specimen now in the University museum, collected by Mr. H. T. Martin recently, is remarkable in showing the scuta of the tarso-metatarsal region, together with the feathers. A photographic reproduction of this part of the specimen is shown in pl. VIII. I have sketched in the tarso-metatarsal bone, to show its position. Indications of feathers are also seen on the back portion of the head, and everywhere they appear to be more plumulaceous than the ordinary type of feathers.

     In pl. VI is shown the restoration of Hesperornis regalis, after Marsh, together with figures of the jaws and of the teeth (pl. VII) It may be added that the birds were of a low degree of intelligence, as proven by the small size of the brain.

     Ichthyornis was as different from Hesperornis as a dove is from an ostrich. While in Hesperornis the wings were rudimentary and the breast-bone without a keel, in Ichthyornis the wings were large and powerful and the keel well developed. All the members of this group were small, none perhaps much larger than a dove. The bones were hollow, as in most recent birds. The jaws had teeth, like those of Hesperornis, and the birds doubtless fed upon fishes or other small animals. The most peculiar character was, however, the structure of the vertebrae. In all recent birds, as also in Hesperornis, the vertebrae have a peculiar articulation, which permitted ample flexure in all directions. The articulation is what is called reciprocal motion, or the saddle-shaped articulation, found, for instance, to a moderate extent in the vertebrae of the human

WILLISTON.]                              Birds.                                     49

neck. In this articulation the end of the centrum has the surface concave in one direction and convex in the other, corresponding to similar but reversed concavity and convexity in the adjacent surface of the contiguous vertebrae. In Ichthyornis this peculiarity was almost wholly wanting, the two ends of the centrum being nearly alike and gently concave in the middle. This concavity is not nearly so deep as in fish vertebrae, but is nevertheless of that type, which suggested the generic name from ichthyos, fish, and ornis, bird. In other respects Ichthyornis did not differ notably from the common flying birds of the present time. Among recent birds the tern seems to approach Ichthyornis most closely, due, doubtless, to similar modes of life. In pl. VII will be seen the vertebrae and jaws of Ichthyornis, after Marsh.

     Because Hesperornis was a swimming bird and Ichthyornis a bird of powerful flight, skimming over the waters after the manner of the petrel, they have been more subject to fossilization than the strictly land-inhabiting birds were. Certainly there were many other species and genera of birds in existence at the time when these lived, since the great difference between the two forms could not have been attained without the development of many other forms. Of these, however, we have very few or no remains. Whether all birds contemporary with them were toothed or not it is impossible to say, but the probability is that they were.

     In pl. V a restoration of Hesperornis as in life is shown, as drawn by Mr. Prentice, under my direction. Of course the coloration is largely conjectural; it is that indicated by living birds of similar habits.

EXPLANATION OF PLATES.

PLATE V.-Life restoration of Hesperornis regalis Marsh. Drawn   by Sydney Prentice.

PLATE VI.-Skeleton of Hesperornis regalis Marsh. After Marsh.

PLATE VII.-Figs. 1, 2, jaws of Ichthyornis dispar Marsh, twice natural size; 3, 4, cervical vertebra of same, twice natural size; 5, 6, mandible of Hesperornis regalis Marsh, half natural size; 7, 8, vertebra of same, natural size; 9, tooth of same, much enlarged. All after Marsh.

PLATE VIII.- Photograph of scutes and feather impressions of the tarsal region of Hesperornis species, from a specimen in the University of Kansas museum. Enlarged.