William D. Turnbull 



Assistant Curator 

 Fossil Mammals 



Figure 1 : View of carnivore den 

 showing the massive sandstone 

 tumble-blocks which protected the 

 bone-filled lens of rock from rapid 

 erosion. (Location of lens out- 

 lined in white.) 



A 

 F 

 C 

 D 



il 



OSSl 



arnivore 



en 



Once in a lifetime, a truly unique 

 concentration of fossils is discov- 

 ered. This summer the Museum was 

 fortunate in acquiring just such an ac- 

 cumulation of rare fossils, consisting of 

 hundreds, perhaps thousands, of skull 

 and jaw fragments, and an even greater 

 number of post cranial pieces, which are 

 remains of small mammals that lived 

 during Early Tertiary time. 



The bones were found in the DeBeque 

 Formation of western Colorado, and 

 were embedded in a lens-shaped body 

 of limy clay, about four feet in diameter 

 and four or five inches thick in the cen- 

 ter. In addition to the abundant and 

 diverse kinds of small mammals, lizard 

 and bird bones have been recognized 



Page k 



among the fragments. The most likely 

 explanation for such an accumulation of 

 small animal remains — broken and dis- 

 articulated as they were — is that it rep- 

 resents the den or roost of a carnivore or 

 carnivorous bird. In this case, I believe 

 the discovery to be a rare carnivore den. 

 Professor Bryan Patterson (formerly 

 Curator of Fossil Mammals, now Agas- 

 siz Professor at Harvard and Museum 

 Research Associate) in twenty years of 

 collecting for Chicago Natural History 

 Museum in the DeBeque Formation had 

 never been lucky enough to come across 

 such a concentration of small mammals. 

 He did build up a splendid collection of 

 larger fossil mammals and, while dis- 

 covering many exciting materials, also 



made a number of enthusiastic friends 

 for the Museum in the areas where he 

 worked. It is one of these friends, Mr. 

 Al Look, of Grand Junction, Colorado, 

 who was responsible for our receiving 

 notice of this present find, and for our 

 opportunity to collect the specimens. 



Over the years, Mr. Look has sent in 

 to the Museum, or otherwise called to 

 our attention, many interesting speci- 

 mens. Last fall, following one of Mr. 

 Look's talks on the geology and archae- 

 ology of western Colorado, 1 a young 



1 Mr. Look is the author of a popular book 

 on the geology of the mountain states, "In My 

 Backyard." Through his book and his popu- 

 lar lectures, he has done a great deal to interest 

 westerners in the nation's geology. 



