280 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1923 



saurus 21 and a series of descriptive papers by Brown, Lambe, Parks, 

 and others are the most important published contributions in this 

 field. 



CENOZOIC MAMMALS OF WESTERN AMERICA 



In the field of Tertiary mammals progress has been made at many 

 points. The great series of Tertiary faunas in this country has 

 been improved all along the line. Collections from each horizon 

 have been greatly increased; many new or little known species are 

 now represented by complete skulls and skeletons. Careful in- 

 tensive stratigraphic work in the fossil fields and more exact records 

 of all specimens enable us to define more accurately the limits and 

 succession of faunas and evolution of phyla. A great advance has 

 been made in the Lower Eocene and Paleocene faunas, the former 

 representing, as I see it, the true beginnings of the Tertiary mam- 

 malian succession in this country, while the latter, whatever its 

 precise geologic position may prove to be, is essentially the culmina- 

 tion and close of a Cretaceous mammal fauna whose earlier evolu- 

 tionary stages are wholly unknown to us, either because they in- 

 habited upland areas, where their remains were not preserved, or 

 because they lived in some other region whose Cretaceous land 

 faunas have not yet been discovered. 22 



In the Lower Eocene the most remarkable discovery is the Diat- 

 ryma, a gigantic ground bird resembling the Phororhachos of the 

 South American Miocene, but not related to it and standing apart 

 in a group by itself. 28 



In the Oligocene, Sinclair 2i has inaugurated an intensive strati- 

 graphic-faunal stud}" of the typical White River bad-lands that will 

 serve as a foundation for comparison and correlation much more 

 exact and accurate than has been possible hitherto. A remarkable 

 fossil quarry opened by the Denver Museum 25 in the Chadron forma- 

 lon of Colorado has yielded already a large series of well preserved 

 skeletons and appears to contain still vast numbers. 



In the Lower Miocene the great collections of the Carnegie Mu- 

 seum from the Agate fossil quarry have been described by Holland 



21 H. F. Osboin and C. C. Mook (1921): Camarasaurus, Amphiccelias and other 

 Sauropods of Cope. Mem. Amer. Mus. Nat. Hist., n. s., vol. iil, pp. 247-387, pis. lx-lxxxv. 



22 W. D. Matthew (1913, 1917) : Bull. Amer. Mus. Nat. Hist., vol. xxxli, p. 307 ; vol. 

 xxxvii, pp. 569, 831 ; 1914, Bull. Geol. Soc. Amer., vol. 25, p. 381 ; 1921, Am. Jour. Scl., 

 vol. ii, p. 209. 



a W. D. Matthew and W. Granger (1917): The skeleton of Diatryma. Bull. Amer. 

 Mus. Nat. Hist, vol. xxxvii, pp. 307-326. 



M W. J. Sinclair (1921-1922) : Four articles in Proc. Am. Phil. Soc, vols, lx and lxl. 



215 J. D. Figgins (1921) : Ann. Rep. Colorado Mus. Nat. Hist., p. 16. 



