"2 S Win dha men — The Cretaceous- Tertiary 



maintain from these facts a Cretaceous age of the Pata- 

 gonian mammal faunas, as Ameghino did. The mam- 

 malian faunas did not live in Cretaceous time, but a small 

 surviving part of the reptile fauna reached into the 

 period of prevailing mammalian faunas. 10 It seems to me 

 characteristic that no reference has been made to the 

 appearance of Sauropoda in association with mammals, 

 and wherever cases of contemporaneity of mammals and 

 dinosaurs in Patagonia have been instanced, these latter 

 belonged to the carnivorous Theropoda. There are rea- 

 sons for supposing that at least the S auropoda-gr oup 

 became entirely extinct in the Cretaceous. 71 



In other words, from the preceding explanations there 

 results a remarkable simplification of the stratigraphic 

 scheme and of some paleontologic questions. The pre- 

 tended complexity of the alleged phenomena disappears, 

 if the San Jorge-transgression is put in the right place 

 and appreciated as an important factor in the strati- 

 graphic division. 



Among the other sections of general interest in the 

 region of the Gulf of St. George, we may briefly review 

 those described by Stappenbeck. This author gave a 

 detailed classification of Salamanca Beds in the valley 

 of the Rio Chico about 20 miles down the river from the 



70 This is also apparently the opinion of Dr. W. D. Matthew in the above 

 mentioned symposium of the Geological Society, p. 401. See also the 

 review of this problem by E. Hennig, Naturwiss. Wochenschrift. N. F., 13, 

 No. 52, 1914. — W. T. Lee, Recent discovery of dinosaurs in the Tertiary, 

 this Journal, vol. 35, May, 1913. 



71 After having written these lines, I received the paper of W. D. Mat- 

 thew, Climate and Evolution (Annals New York Acad, of Sciences, vol. 

 24, 1915) in which the question of the age of Argentine geologic formations 

 in comparison with European and Northamerican standards has also been 

 thoroughly treated. In the chapter "Synchronism and Homotaxis" the 

 author suggests the idea that the peculiar contradictions between 

 Ameghino 's time demarcations and the generally adopted schemes might 

 be due to the fact that "the data on which they rest do not prove con- 

 temporaneity but homotaxis. Granting that two faunas in widely remote 

 regions contain the same proportion of extinct species, granting that they 

 represent equivalent stages of evolutionary progress, they are not thereby 

 shown to be contemporaneous, unless they are at the same distance (meas- 

 ured not in miles but in difficulty of advance) from the main center of 

 dispersal of the fauna they contain. ' ' From this point of view, Dr. Mat- 

 thew draws the inference that ' ' the late Tertiary mammals of the southern 

 continents will approximate in homotaxis the Middle or Early Tertiary 

 mammals of Holarctica; and the Middle Tertiary southern faunas will 

 approximate the Early Tertiary or Late Cretaceous faunas of the north. ' ' 

 I trust that the new data published in this paper may help to show that 

 it is not necessary to look for explanations, which have an obviously 

 artificial character. The Cretaceous age of the Patagonian mammalian 

 faunas is not supported by a single valid fact. Those paleontologists who 

 like Gaudry, Schlosser and Philippi defended the Tertiary age of these 

 faunae, are now completely justified by the results of this research. 



