110 



SCIENCE. 



[N. S. Vol. XXII. No. 552. 



genial; and the last of their kind perished 

 so utterly at, or immediately after, the 

 close of the Cretaceous period that the 

 earth has since contained no living repre- 

 sentative of any of them. 



I once tried to account for the sudden 

 disappearance of the dinosaurs by sup- 

 posing the coalescence of continental areas 

 which they occupied with others upon 

 which powerful Eocene mammals had been 

 separately introduced, assuming that the 

 final destruction of the dinosaurs occurred 

 in the fierce conflicts which would nat- 

 urally follow. But such a suggestion pre- 

 supposes the contemporaneous existence, in 

 separate regions, of highly organized and 

 characteristic Mesozoic and Tertiary verte- 

 brate faunas, which one is naturally slow 

 to believe. The occurrence of such conti- 

 nental changes has not been proved, and 

 no paleontological battlefields, with min- 

 gled remains of the mighty combatants, 

 have ever been discovered. It seems im- 

 possible to conceive of the applicability of 

 the theory of the origin of species by nat- 

 ural selection to any of the chief features 

 of the strange faunal history of the dino- 

 saurs, or to their sudden origination and 

 extinction. 



"We know little or nothing of the an- 

 cestry, or of the genetic succession of the 

 unique, abundant and universally distrib- 

 uted flora of the Carboniferous age. It 

 differed materially in character from that 

 of the flora which preceded it, and it was 

 even more different from all succeeding 

 floras. Its forms were so diverse, and 

 their family characteristics so distinctly 

 defined, that the idea of such a gradual 

 transition from one to another as the 

 theory of their, origin by natural selection 

 requires seems to be wholly inadmissible. 



The palms and exogenous trees, repre- 

 sented by the right-hand line under G on 

 the diagram, were introduced with appa- 



rently great suddenness in late Jurassic 

 time, and those earliest known plants of 

 their kinds had essentially the same grade 

 of organization that those kinds now pos- 

 sess, although their subsequent evolution 

 has been comparatively slight as regards 

 floral rank. 



Birds, having unmistakably reptilian 

 characters, are known by their remains to 

 have existed in the Jurassic and Cretaceous 

 periods ; but remains of the earliest known 

 true birds, such as are referable to any of 

 the living orders, are found in strata of the 

 Eocene Tertiary, and they seem to have 

 originated suddenly in that epoch. These, 

 and all living birds, differ greatly from 

 those older kinds, and no intervening kinds 

 have been discovered. It is true that in 

 this case, as in other similar cases, the 

 paleontological record is far from com- 

 plete, but the epochs in which the older 

 and later forms, respectively, are known to 

 have existed were apparently separated by 

 a time interval which was much too short 

 to have produced such wide differences by 

 the slow process of natural selection. 



Eemains of the earliest known teleost 

 fishes are found in latest Jurassic and early 

 Cretaceous strata. They were structurally 

 very different from all known earlier fishes 

 and possessed in full the distinguishing 

 characteristics of the teleosts as they exist 

 to-day. To say that no evidence of the 

 gradual and slow evolution of the teleost 

 fishes from older and very different ich- 

 thyic forms has ever been discovered is but 

 to repeat what has been said of the sudden 

 appearance of other highly organized 

 forms. 



A similar degree of suddenness marks 

 the introduction of the placental mam- 

 malia, which occurred about the beginning 

 of Tertiary time, as is shown by the right- 

 hand line under F on the diagram. Those 

 highly organized animals assumed faunal 



