110 BARON F. NOPCSA ON THE PRIMITIVE REPTILIA |_Vol. lxxix, 



the whole continent rose, these depressions continued to become 

 deeper. This sinking caused the local accumulation of 6000 feet 

 of coarse gravel and even conglomerate, showing no decrease in the 

 size of its constituents, and proving thus that the gradient of the 

 fall of the different rivers entering into the lake was for a very 

 long time the same. 



For the information of those unacquainted with such gigantic 

 non-marine accumulations, it is worthy of note that, at a later 

 period in the Carpathians, the brackish-water transition-beds 

 between the Oligocene and the Miocene (the Aquitanian strata), 

 which likewise consist of clays, sandstones, conglomerates, and 

 lawyers of coal, attain near Petrozseny a thickness exceeding 2100 

 feet (53). 



It is similarly interesting to note, as a second example of the 

 sinking of the base while sedimentation is going on, that in the 

 great Hungarian plain (Alfold) the diluvial-fluvial accumulations 

 go down at Zombor to a depth of 62 feet, at Szabadka to 290 feet, 

 .and at Szeged to 386 feet. Nevertheless, the grain of the sedi- 

 ment does not change in the least, and it continues to be the same 

 even in the Levantic strata, which go down at Zombor to 300 feet 

 below the uppermost diluvial sediments, and in Szabadka to 

 800 feet. The Pontic strata were nowhere encountered, although 

 one of the artesian wells which furnished the data was driven at 

 Szabadka to 1800 feet (27). 



Evidently, similar processes account for the 6000 feet of Danian 

 rocks at Hatszeg, which continued to transgress continuously over 

 older strata, although the surface of the country as such was 

 rising. 



The maximum of emergence was attained in Southern Europe 

 at the dawn of the Eocene, when even the Danian lakes and 

 swamps were drained by rivers, and ib seems as if at that time the 

 different patches of dry land in South-Eastern Europe were united 

 to the Russo- Asiatic continent. Evidently, the newly-formed 

 land-bridge brought the Eocene mammals into Europe. In the 

 Middle Eocene sediments of Transylvania ProJii/racodon orientalis 

 and Bracliydiastematherium transylvanicum are already to be 

 met with (37). The Lower Eocene is missing in the whole of 

 Transylvania (36). 



V. The Causes op the Extinction op the_Upper 

 Cretaceous Vertebrates. 



Taking into account the geological changes set forth in the 

 foregoing pages, we can easily understand why ancient pre- 

 Cenomanian types of terrestrial animals persisted in South-Eastern 

 Europe until the end of the Danian stage. We can, moreover, 

 find an explanation for the remarkably small size of the Dinosaurs 

 of this fauna, for that seems to be an effect of the restriction to 

 the small Senonian islands, which affected neither the smaller 

 crocodiles nor the comparatively small tortoises, but only the 



