HES'PERIS. See DA IrESPERORNIS, (Neo-Lat..
from IVA-Epos., liesrrros, west 6pos, ornis, bird). A primitive. flightless, toothed sea-bird, found fossil in the Middle Cretaceous shales of western Kansas, and. exceptlu g.trchtcnpleryx, t lie oldest bird known. The first skeleton was di-wav ered in IST1 by Prof. O. C..larch, near the Smoky Dill River, in marine deposits of yellow chalk and calcareous .shales, and was named Ilesperornis regaliA Several other speeies have since become known: and Enaliornis, of the Up per Grectisand of C'ambridge. England. appears to it a closely allit tl form. It was a large, well feathered water-bird. having the general habits of a loon, perhaps, ranging the open sea, and scrambling upon land only for breeding. Its food was mainly fishes, which it pursued by swimming and diving, for it had no wings. There is reason to believe that this winglessness was due to degeneracy from fully winged ancestors. }lesperornis was more than live feet in length, and if its ancestors were equally bulky their wings were quite too large to use under water, but would be folded close against the body when the bird dived or swam. This constant dis use, as the race became more and more exclusively aquatic. would per mit the wings to dwindle. By the time the wings were small enough to be of use as paddles under water. as modern auks use theirs, the muscles had become too feeble to move them in so dense a medium, and so degeneration continued until only a remnant of humerus re mained. Correlative with this was a constant growth and strengthen ing of the legs. which became of great size (though the bones re mained hollow, like those of an aerial bird) and so twisted as to turn edgewise when the foot was brought forward after each stroke, thus offering least resistance to the water. The original skeleton set up by Marsh, and depicted in his (Mon fora/Meg, stood erect like a penguin. When an attempt was made at the National Museum to mount another skeleton in swimming attitude, it was dicovered that this position required an altogether novel arrange ment of the legs. such as is shown in the ac companying sketch of a re:tbration based by Lucas (see above) upon this skeleton. It ap pears that the legs of this bird must bare stood out almost at right angles. and have acted like a pair of oars.
To this most powerful apparatus for swim ming and ehase was added the best of means for seizing and holding the agile. slippery. and often bone-incased prey, in the form of a long neck. capable of rapid flexure and thrust, and long slender jaws. armed with sharp recurred teeth resembling those of reptiles. They were set in a common alveolar groove (holeodont dentition'— a fact which differentiates Hesperornis from the higher Iehthyornis and its relatives, whose teeth were implanted in separate sockets (thecodontl. (See BIRD, FOSSIL.) In the upper jaw the were confined to the maxillary bone alone. but in the lower jaw they extended to the tip of the ramus. As this lower jaw was united in front only by a cartilage. as a serpent's, and had
on each side. a joint which admitted of sours elbow-like 'notion. the power of swallowing was very extensive. The skull, though shaped like that of a loon. had many struthious eharacters, and the brain was distinctly reptilian in form. and only about one-third as large as that of a modern loon. The skeleton as a whole closely approximates that of modern bird:. The verte bra- resemble those of a loon. The shonlder girdle. in its original structure. as well as in its degeneracy. and the sternum. which has no keel. are ostrich-like; and it is in the pelvic arch more than elsewhere that trace: of reptilian ancestry are evident. The tail contained 12 vertebra--more than are or have been possessed by any other known bird since Arelhcopteryx; and they were solid, firmly locked together and winged. so that the outline of the caudal skeleton is spatulate. This. with the evidently strong mu:eulature, would give great power, similar to that of a bea ver's tail. and doubtless the organ was an Impor tant aid in swimming. by a sculling motion. as well as in steering and controlling progress.
11 nether it bore quill feathers in pairs, as did the long tail Of Archaeopteryx. is not known. The legs and feet resemble those of it grebe on a large scale, and it is fair to suppose that they were externally lobed in a similar way. The feather. on the legs. at least, as is known front impressions in the rocks, were and rather scanty.
liesperornis survived for a long period, during which the interior of North America was a shal low sea, stretching (rout the Alleghenies to the Roeky Nlountains, looken by little except the isl and summits of the Ozark ]tills. Professor larsli says that apparently there was an absence of enemies in the air to be feared by this great diver, since it was more titan it match for the huge but toothless pterodactyls. which hovered over the waters in great Humber,. The warm sea teemed with fishes and other food but it also teemed with great swimming lizards ( mososaurs), turtles a dozen feel in length, and large pre daceous fishes. As the gradual rise of the land toward the (-lose of the Cretaceous epoch more and more inclosed the and modified comfi t' s. the struggle for life became too hard for many of its denizens. and liesperornis was among those whit+ early succumbed. With it disappeared itirelet a primitive type of bird life, for this blanch of the ovine Hoek sVell•g to have ternanated without leaving any descendants.
Btamonicicilv. The fullest deFeriptions and illustrations of Ilesperornis are contained in Marsh. Oftontornithes: A Monograph of the Ex tinct Toothed Birds of North .1«irrica (]Washing ISM)) . Consult, also: Cope, Cretaceous celebrates of the West (Washington, ; Williston, various papers in the Annual Reports of the Cnirersity I;eologiral Surrey of Kansas (Lawrence) : Lucas, Animals of the Past (New York. 19011: Newton. Dictionary of Birds (New York. . See BIRD, FOSSIL I and