34 



HARDWICKE'S SCIENCE-GOSSIP, 



Museum of Yale ; " and the announcement that much 

 of the material for the completion of others is in an 

 advanced state of preparation. The initial volume of 

 what promises to be a most remarkable series, is 

 devoted exclusively to the Odontornithes, or toothed 

 birds. In method of treatment it can be compared 

 only with the classical contributions of M. Alphonse 

 Milne-Edwards to the history of fossil birds, while 

 for typographical excellence, and the number and 

 beauty of the finely-executed plates, it stands pre- 

 eminent, even among the many fine palreontological 

 works that have been issued in America. 



During the publication of the justly celebrated 

 "Recherches pour servir a I'histoire des oiseaux 

 fossiles," the existence of Mesozoic birds was unproven, 

 if suspected, and for long after the world-famed 

 Archffiopteryx of Solenhofen, now represented by 

 a second and more perfect specimen in the Museum 

 of the University of Berlin, was the sole representative 

 of its class. A few subsequently discovered frag- 

 mentary remains from the Greensand proved the fact 

 of the persistence of the group through the Cretaceous 

 epoch. Now we know that nine genera and twenty 

 species existed in America alone during the deposition 

 of that series. Most of these were discovered in soft 

 marly deposits of middle Cretaceous age on tlie 

 eastern slopes of the Rocky Mountains in Kansas and 

 Texas. They occurred, associated with the remains 

 of Plesiosaurians, toothless Pterodactyles, mosasauroid 

 reptiles, and numberless species of fishes and mollusks. 



Professor Marsh describes two widely separated 

 avian types as co-existing in one region at that period. 

 These, however, possessed one character in common — 

 jaws set with teeth so unbird-like and sauroid 'in 

 shape, mode of implantation and reproduction, that 

 they might readily be mistaken for those of true 

 reptiles if discovered unassociated with the remains 

 of the avian skeleton. The Odontornithes or " toothed 

 birds " are divided into two groups. The type genus 

 of the Odontolcce, those with grooved jaws, being 

 that remarkable wingless, "Western" bird (Hesper- 

 ornis) which bore most resemblance to the grebes. 

 It stood over three feet in height, and almost in- 

 capable of movement on land, was a powerful diver 

 and swimmer, with a long flexible neck and robust 

 limbs, especially adapted for swift propulsion in the 

 water and a broad tail of nearly beaver-like propor- 

 tions. This genus possessed the saddle-backed arti- 

 culation of the vertebrae characteristic of almost all 

 known birds. The structure of the rudimentary wings, 

 keclless breast, shoulder girdle, and skull recalls that 

 of the ostrich, and its very robust hind limbs exhibit 

 as much specialised modification for an exclusively 

 aquatic life as those of that genus for swift running 

 on land. In fact Hesperornis led an essentially 

 aquatic life, fed on the fishes of the Ci^etaceous ocean, 

 resorting to the nearest land, a low series of islets now 

 the site of the Rocky Mountains, only in the breeding 

 season. 



The second group of Odontotormce comprises a 

 number of small keel-breasted short tailed flying 

 birds referable to the genera Apatornis (one species) 

 and Ichthyornis. These also led an aquatic life, and 

 the teeth which were sunk in distinct sockets in their 

 slender saurian jaws enabled them to catch and hold 

 with dexterity the fish on which they fed. "Ichthy- 

 ornis in many respects probably resembled the modern 

 terns in its mode of life. The powerful wings and 

 small feet suggest similar habits in flight and rest- 

 That Ichthyornis was provided with feathers, is proved 

 beyond a question by the tubercles for the attach- 

 ment of the quills in the forearm. It lived at a time 

 when the only other denizens of the air at present 

 known to have inhabited the same region were the 

 toothless Pterodactyles," This genus differed from 

 all its known contemporaries and successors in 

 possessing vertebrae concave at both ends like those 

 of fishes, and therefore devoid of the curious saddle- 

 shaped articulation characteristic of all other birds, 

 the origin of which was hitherto veiled in mystery. 



In the third neck vertebra of Ichthyornis victor- 

 Professor Marsh detected a clue to his peculiar modi- 

 fication and the development of the modern style of 

 avian vertebra from the fish-like biconcave form. 

 All the other vertebra of that genus resemble those of 

 fishes, and the anterior articulation retains its cup- 

 shaped form. But the third cervical of T. victor 

 presents iritermediate characters, and "we catch 

 nature in the act as it were of forming a new type by- 

 modifying one form of vertebra into another." This 

 change Professor Marsh concludes was originated by 

 increasing movement in a vertical plane. This de- 

 flected the upper and lower margins of the circular 

 cup, produced vertical constriction, and at the same 

 time left the side margins projecting. The change 

 began and was first perpetuated at the bend of the 

 neck where most movement was jiossible, and 

 being advantageous to the birds was extended to the 

 successive cervical, dorsal, and sacral joints of the 

 vertebral column. The fact that the saddle-shaped 

 articulation in existing birds is most marked in the 

 anterior regions, where full and free movement is not 

 arrested by the ribs and neural spines, supports this 

 conclusion as to its development in this manner from, 

 the primitive fish-like concave form of vertebra. 



Professor Marsh's bird studies have also revealed 

 the interesting fact, that the very significant law of 

 progressive brain growth known to be characteristic 

 of the Mammalia is equally applicable to the birds.. 

 This conclusion is based on the evidence afforded by 

 the skulls of Cretaceous genera, described in tlie 

 memoir which show that tlie avian brain at that period 

 was small and reptilian in character. The cerebral 

 hemispheres in Hesperornis are about one-third less 

 than those of the loon, a bird about the same size 

 and habits, and the same disjDroportion is noticeable 

 between the brain cavity of Ichthyornis and that of 

 the tern, its nearest ally. We reproduce Professcr 



