Geology . eflightless birds (Hesperornis), the other of small birds of powerfulflight (Ichthyornis). The Hesperornis (Fig. 415), was a large, flightless,highly specialized diver, with aborted wings and remarkable leg develop-ment. The wings had almost vanished, a single bone only being implies that, following the evolution which had produced thewings, there was a degenerative history long enough for them to dwindle THE CRETACEOUS PERIOD. 183 almost to the point of extinction. Concurrent with this, and doubt-less its cause, was an extraordinary development of the legs by whichthey bec
Geology . eflightless birds (Hesperornis), the other of small birds of powerfulflight (Ichthyornis). The Hesperornis (Fig. 415), was a large, flightless,highly specialized diver, with aborted wings and remarkable leg develop-ment. The wings had almost vanished, a single bone only being implies that, following the evolution which had produced thewings, there was a degenerative history long enough for them to dwindle THE CRETACEOUS PERIOD. 183 almost to the point of extinction. Concurrent with this, and doubt-less its cause, was an extraordinary development of the legs by whichthey became not only very powerful, but their efficiency as paddleswas increased by the bones of the foot being so joined to those of theleg as to turn edgewise in the water when brought forward. Notonly this, but, strangely enough, the legs were so joined to the bodyframe as to stand out nearly at right angles to the latter, like a pairof oars, instead of standing under the body as walking legs universally Y 1*0*. Fig. 415a.—Restoration of the great toothed diver of the Cretaceous, Hesperornis,by Gleeson, based on a skeleton in the U. S. National Museum. (From LucasAnimals of the Past; by permission of the Publishers, McClure, Phillips & Co.) Apparently walking as well as flying had been abandoned, andthe organism was specialized for swimming and diving only. The head,neck, and body were elongate and admirably shaped for plungingthrough the water. Favored by the powerful specialized hind limbs,the Hesperornis was doubtless a swift swimmer and an expert diver,and must have been a formidable enemy to the sea life on which itchose to feed. Its jaws were armed with teeth set in a groove in primi-tive saurian fashion, and, like the jaws of snakes, were separable soas to admit large prey. As these strange birds attained a length ofsix feet in some cases, their victims may have embraced fish and rep-tiles of considerable size. As they have been found in Kansas, Mon-1 Lucas, Animals of
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