29 
A NEW SPECIMEN OF EODELPHIS CUTLERI 
FROM THE BELLY RIVER FORMATION 
OF ALBERTA 
By George Gaylord Simpson, 
American Museum of Natural History 
Page 
80 
Illustration 
Plate VII. Illustration of fossil. 
INTRODUCTION 
On May 30, 1916, Doctor (now Sir) Arthur Smith Woodward announced 
the discovery of a lower jaw of a mammal in the Belly River formation 
of Albertah A few months later a more detailed description and a figure 
of this important specimen, to which he gave the name Cimolestes cutleri, 
new species, were published^. In the meantime, without knowledge of 
Smith Woodward’s work. Dr. W. D. Matthew described a similar specimen, 
naming it Eodelphis hrowni, new genus and species’. 
The type of Cimolestes” cutleri was found by William E. Cutler in 
1914 on Sand creek, Red Deer river, Alberta, and consists of part of the 
right ramus with P 3 , Mi-g, and roots or alveoli of other teeth. That of 
E. hrowni was found by Barnum Brown in 1915, also on Sand creek, 15 
miles below Steve ville, and consists of the left lower jaw nearly complete 
but with the teeth very much worn, a small fragment of the right lower 
jaw, and two skull fragments. The importance of these two discoveries 
lay chiefly in the fact that they were, at that time, the most complete known 
specimens of Cretaceous mammals and that they could be definitely 
shown to be marsupials, confirming previous belief that this group was 
largely represented in the American Upper Cretaceous. Eodelphis is still 
the oldest known marsupial. 
The type of “Cimolestes” cutleri has been redescribed by the present 
writer,^ who referred it to Matthew’s genus as Eodelphis cutleri (Smith 
Woodward). The distinctions between the two specimens, aside from 
verbal discrepancies in the original descriptions of the molars, were con- 
sidered as probably too slight to warrant recognition of both trivial names, 
but these were retained pending some discovery which might provide 
definitive knowledge of molar structure in this genus. 
This discovery has now been made. During the past summer (1928), 
C. M. Sternberg found a third Eodelphis jaw that clearly reveals the molar 
structure, permits better correlation of the two previous finds, and adds 
another to the four or five really adequate mammalian specimens so far 
found in the Cretaceous of this continent. For the privilege of studying 
this specimen and of preparing the present remarks, the writer is much 
indebted to Mr. Sternberg. 
>Zool. Boc. London, Abstract No. 158 (May 30, 1916). 
*Proc. Zool. Soc. London, 1916, pp. 525^28 (Sept., 1910). 
•Bull. Am. Mufl. Nat. Hist., XXXV, pp. 477^ (July 24, 1916). 
•Catalogue of the Mesozoic Mammalia, etc., British Museum (Nat. Hist.), pp. 147-149 (Mar. 24, 1928). 
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