PALEONTOLOGY 133 



marsupial or placental Mammals, linking them to the 

 Marsupial, have yet been found in any part of the 

 world, notwithstanding the occurrence in many re- 

 gions over America, as well as the other continents, 

 of a gradual passage from the Cretaceous formation 

 into the Tertiary. They are naturally supposed to 

 have existed in the later Cretaceous over the dry land 

 of eastern and western America; but still it is strange 

 that they did not find resorts somewhere on the bor- 

 der of the Cretaceous seas along with the Mar- 

 supials." * 



It is evident that Dana is disappointed at the ab- 

 sence of the remains of placental mammals from the 

 later Cretaceous, where marsupials are abundant. I 

 know of no plausible theory by which the evolution- 

 ist can account for this important fact of imperfect 

 record. 



"Another strange fact is that although the Marsu- 

 pials of earlier time had become variously special- 

 ized, their placental successors should have had un- 

 specialized or prototype characters." t 



This fact, of course, goes to negative the theory 

 that the Eocene mammals were evolved from Creta- 

 ceous marsupials. Continuing with regard to the 

 difficulties in the way of evolution, Dana says: 



" s Diversity of Eocene Mammals. Another remark- 

 able fact is that so great a diversity of Mammals, 

 diversity in structure as well as size, should have 

 appeared before the Eocene period had passed. The 

 prototypic plant-eaters and flesh-eaters of the earliest 

 part, supposed to be plantigrade in feet, were fol- 

 lowed, even in the Wasatch division of the lower 

 Eocene, by species of large, short-footed Ungulates, 

 the Coryphodonts, and in the later Eocene huge 

 Dinocerata, the latter supplied with horns for attack 



* Manual ol Geology, p. 928. t Ibid, p. 928. 



