OcToiiEK 2, 1885.] 



SCIENCE, 



295 



THE RELATIONSHIPS BETWEEN DINO- 

 SAURS AND BIRDS. 



Pkof. B. Yetter 1 has recently published a strik- 

 ing article upon this question, which offers strong 

 evidence that the view so long held of the descent of 

 birds from dinosaurian reptiles must be abandoned. 

 The author gives several pages to a resume of the 

 more or less discordant opinions of previous writers; 

 but these lack of space forbids us to notice, as Dr. 

 Tetter's own views must claim our attention. 



The oldest known dinosaurs occur in the trias, 

 and are representatives of the Theropoda and Sauro- 

 poda, — the former typical carnivores, walking entirely 

 upon the three-toed hind-feet; the latter herbivorous, 

 little differentiated, having the fore and hind limbs 

 plantigrade, pentadactyl, and of nearly equal length. 

 From this it appears that the earliest members of 

 the dinosaur line existed long before tlxe trias, and 

 must have been quadrupeds, with skull, limbs, and 

 pelvis approximating the lizard type. Of the meso- 

 zoic dinosaurs, we know at least five or six diver- 

 gent lines which show more or less likeness to birds 

 in the pelvis and hind-limbs. These do not form 

 a single connected series gradually leading to the 

 birds, but rather a number of divergent series. Let 

 us examine some of these groups. 



Stegosauria show many bird-like features of the 

 pelvis and hind-limb, but in every other respect are 

 very different from birds, having a lacertilian skull, 

 an immense tail, and grasping fore-limbs. They are 

 too specialized to be bird ancestors. The Ornitho- 

 poda have, with Compsognathus, usually been re- 

 garded as forerunners of the birds. Iguanodon will 

 serve as a type of the group. It walked on its 

 elongated hind-legs. The jaw was toothless in 

 front, and very probably had a horny beak. The 

 pelvis is very like that of a Ratite, though with large 

 reptilian pubes ; the femur has a third trochanter; 

 and the tibia is as long as the femur. The foot cor- 

 responds very closely to the embryonic condition of 

 the bird's foot. The specializations of Iguanodon, 

 however, will not allow us to regard it as a bird 

 ancestor. These are, the entire configuration of the 

 skull, the peculiar tail, the absence of clavicles, the 

 dermal armor, the structure of the fore-limb (which 

 is much shortened). The first finger possesses a dag- 

 ger-like weapon; the second, third, and fourth, hoof- 

 like, ungual phalanges; and the fifth, which diverges 

 strongly from the others, a claw. May we not, how- 

 ever, imagine a more generalized form as the common 

 ancestor of both Iguanodon and the birds ? But it 

 was merely the specializations of Iguanodon that sug- 

 gested it as a bird ancestor. If we remove these, the 

 simpler sauropodan or even lizard characters appear. 

 Here, at least, we must not speak of homologies with 

 the bird foot and pelvis, but only of analogies. This 

 does not render the facts uninteresting, as they prove 

 anew, how, by the steady operation of the same 

 needs, nearly the same result may be produced from 

 similar raw material, be the remaining structures 

 never so different. For similar reasons Dr. Vetter 



1 Festschrift der naturwiss. gesellsch. ' Isis ' in Dresden, Mai, 

 1885. pp. 109-122. 



rejects Coelurus and Hallopus from the category of 

 possible bird ancestors. 



In Compsognathus the hind-limb is remarkably bird- 

 like, in the following respects more so than in the 

 Ornithopoda: femur considerably shorter than tibia; 

 distal end of fibula a mere style; astragalus anchylosed 

 with tibia, calcaneum with fibula ; tarsus, metatarsals, 

 and phalanges exceedingly similar to those of embryo 

 birds; (in almost all these respects Archaeopteryx 

 comes nearer the modern bird-type, without quite 

 reaching it.) On the other hand, Compsognathus 

 possessed a long ischiadic symphysis, very probably 

 long pubes, greatly shortened fore-limb, the hand 

 clawed and three-fingered, non-pneumatic bones, a 

 lacertilian skull, long neck and tail. Such an animal 

 may represent a further developed side-branch of the 

 Ornithopoda, but was already spoiled as a flyer. Dr. 

 Yetter rejects the opinion that Compsognathus could 

 have been an ancestor of the Ratitae, as he derives 

 both classes of birds from a common form. The 

 result, then, of this investigation, agrees quite closely 

 with that of Seeley and Yogt, that there is no direct 

 connection between dinosaurs and Carinatae at least, 

 and probably none with the Ratitae. If, as seems in 

 every way probable, the Carinatae and Ratitae are de- 

 scended from a common ancestor, the latter cannot 

 be derived from the dinosaurs. 



PHOSPHORESCENCE OF MARINE 

 ANIMALS. 



Eheenbeeg, in his 'Das leuchten des meeres,' 

 published in 1835, quotes four hundred and thirty- 

 six authors who had written upon this subject up to 

 that time; and very many additional observations 

 have been since recorded. The property of phos- 

 phorescence is common to certain members of the 

 Protozoa, and to the coelenterates, echinoderms, 

 worms, rotifers, crustaceans, molluscoids, mol- 

 lusks, and fishes, among the Metozoa. Fully three- 

 fourths of Professor Mcintosh's interesting address 

 was devoted to a review of the phosphorescent forms 

 belonging to these several groups; their distribution, 

 and the appearance, intensity, and character of the 

 luminosity being described in some detail. We limit 

 ourselves to a short abstract of the concluding portion 

 of his remarks. 



As regards the causes of phosphorescence. Professor 

 Mcintosh said, " I do not deem it necessary to go into 

 detail with regard to the numerous views which have 

 been advanced to account for the phosphorescence 

 of marine organisms, for these range over a very 

 wide area, — from its production by electricity, by 

 the constant agitation of the water, by putrefaction, 

 by luminous imbibition, to its manifestation as a 

 vital action in the animals, or a secretion of a phos- 

 phorescent substance. . . . 



" It will be observed that in the Protozoa, the struc- 

 ture of the minute but often very abundant animals, 



Abstract of the opening address before the section of biology 

 of the British association for the advancement of science, by 

 Prof. W. C. McIntosh, president of the section. From advance 

 sheets of Nature. 



