28 



SCIENCE 



[N. S. Vol. LIV. No. 1384 



S. Geological Survey " considered all avail- 

 able evidence " it is clear that its weight and 

 tenor was not correctly understood. 



When the subject was discussed by the 

 Palffiontological Society in 1913 I presented 

 a paper outlining the vertebrate evidence, es- 

 pecially with regard to the Paleocene faunas.^ 

 Subsequent researches by Brown, Lambe, Os- 

 born and Parks on the Alberta dinosaurs, by 

 Gilmore on the New Mexican reptiles, by 

 Granger and myself on Paleocene and Eocene 

 mammals, by Stehlin, Teilhard and Schlosser 

 on the Eocene and Paleocene mammals of 

 Europe, by Smith Woodward and myself on 

 the Cretaceous mammals of Alberta, confirm 

 the correlations and conclusions presented in 

 that paper, but strengthen certain views which 

 were then rather suggested than advocated. 



1. The Lance fauna is wholly Cretaceous 

 in character. It is entirely a continuation and 

 specialization of the Judith (late Cretaceous) 

 ■without any new elements, but the amount of 

 evolutionary change in the many phyla that 

 have now been traced through Judith, Edmon- 

 ton and Lance shows that it is considerably 

 later in time. 



2. The earliest placental mammals appear in 

 the Puerco " Lower Paleocene " which may be 

 as old as the Lance or older, although usually 

 regarded as later. The Torrejon and Fort 

 Union faunas, Upper Paleocene, are not much 

 later than the Lance, and the phyletic evolu- 

 tion indicates that they are considerably later 

 than the Puerco. The TifEany and Cemaysian 

 faunas show a still later stage of the Paleocene 

 faunas. ' • ^^ 



3. The Paleocene plaeentals are of primitive 

 and archaic aspect. Although some of their 

 phyla survive into the Eocene, they are as a 

 whole not nearly related to the characteristic 

 and dominant Tertiary Mammalia, and much 

 more primitive. The metatherian mammals 

 (multituberculates and marsupials), a minor 

 but considerable element in the Paleocene 

 faunas, are of distinctly Mesozoic aspect and 

 closely related to those of the Judith and 

 Lance. The reptiles are all Cretaceous fam- 

 ilies continued from the Judith. 



1 Bull. Geol. Soc. Am., XXV., pp. 381-402 Sept. 

 15, 1914. 



4. The true Tertiary mammal fauna appears 

 suddenly at or near the base of the Wasatch, 

 and in the Sparnacian of Europe (London 

 Clay, etc.). It is a new fauna, identical in 

 these two far distant regions, and consists in 

 the main of the modern orders of mammals, 

 which now appear for the first time and evolve 

 through the course of the Tertiary into their 

 present diversity and specialization. The two 

 most important families of Tertiary and mod- 

 ern chelonians (terrapins and tortoises) ap- 

 pear at the same time. 



5. The great faunal break lies at the end of 

 the Paleocene, with the incoming of the Ceno- 

 zoic vertebrates at or near the base of the 

 Wasatch. The European standard has 

 drawn the line above the great chalk forma- 

 tions and below the Thanetian (Cernaysian). 

 The Judith corresponds to the Upper Senonian 

 of Europe, but is older than the Maestrichtian 

 and Danian divisions of the chalk, unquestion- 

 ably Cretaceous, aside from certain formations 

 of disputed age grouped as Montien. The end 

 of the unquestioned Cretaceous in Western Eu- 

 rope is then considerably later than the Ju- 

 dith, perhaps as late as the Lance or later. 

 Its precise correlation can best be made 

 through comparisons of the marine Cannon- 

 ball phase of the Lance formation with the 

 Danian, etc. On the other hand the Tertiary 

 as generally recognized in Western Europe 

 begins at least with the Thanetian, containing 

 the Cernaysian fauna, uppermost Paleocene, 

 equivalent to the Tiffany zione at the base of 

 the Wasatch in the San Juan basin. It is 

 therefore a little below the great migrational 

 break indicated by the vertebrate faunas. 



There are two criteria generally used in 

 faunal classifications, the extinction of ancient 

 types and the first appearance of new groups. 

 The latter appears to me the more logical and 

 practical. By this standard the Wasatch Spar- 

 nacian fauna of the London Clay, etc., is the 

 introduction of the distinctively modern or 

 Cenozoic life, the preceding faunas, even in- 

 cluding the Paleocene plaeentals, being essen- 

 tially the last stages of Mesozoic life. 



This division is not supported by the palaeo- 

 botanists. Their Cenophytic era, it is well 

 recognized, begins with the upper Cretaceous 



