PALEONTOLOGY 131 



Greikie says of these remains: "Though mam- 

 malian remains had long been known to occur in the 

 Triassic and Jurassic formations, none had been ob- 

 tained from Cretaceous rocks, and this absence was 

 all the more remarkable from the great abundance 

 and perfect preservation of the reptilian forms in 

 these rocks. But the blank has now been filled by 

 the remarkable discovery in the Upper Cretaceous 

 rocks of Dakota and Wyoming of a large series of 

 jaws, teeth, and different parts of the skeletons of 

 small mammals belonging to many individuals, and 

 including not a few genera and species. They are 

 found associated with remains of deinosaurs, croco- 

 diles, turtles, ganoid fishes, and invertebrate fossils, 

 indicating brackish or fresh water conditions. The 

 mammalian forms show close affinities to the Triassic 

 and Jurassic types. There are several distinct genera 

 of small marsupials, others seem to be allied to the 

 monotremes, but there are no carnivores, rodents, or 

 ungulates." * (He then enumerates the names of the 

 sixteen genera as proposed for them by Marsh.) 

 "More recently the discovery of a single small tooth 

 in the Wealden series of Hastings is the first trace of 

 mammalian life yet found in the Cretaceous forma- 

 tions of Europe." 



Dana says of the Cretaceous mammals: "The 

 mammals of the Cretaceous thus far discovered are 

 probably all marsupial or monotreme, like those of 

 the Jurassic period. The remains are mainly teeth, 

 with a few broken jaws and limbs." t 



"The Monotremes and Marsupials from the Cre- 

 taceous formation show little progress in Mammals 

 beyond the condition in the Jurassic period — nothing, 

 up to the present time, that bears the decided charac- 

 ter of a placental mammal." \ 



* Text-Book of Geology, p. 935. 

 t Manual of Geology, p. 852. % Ibid, p. 871. 



