64 BULLETIN 16 9, UNITED STATES NATIONAL MUSEUM 



swampy stream course, ox-bow lake, or bayou. From the great va- 

 riety of mammals present this evidently was not the site of a single or 

 selective catastrophe, like many quarries that seem to represent quick- 

 sand or quagmire traps, but must have made a fairly complete sample 

 of the mammals of the surroundmg forest and (to a less extent) glades. 

 Regardless of whether the mammals came here to drink, swam into the 

 water, dropped from trees, or were occasionally washed in, it seems 

 likely that the breaking and scattering of their bones, and perhaps 

 commonly their deaths also, were the result of activities of the carniv- 

 orous fishes and reptiles. Such a history would probably explain the 

 small ratio of bones to teeth (the former eaten and digested and com- 

 minuted, the latter less palatable and more resistant), the many clean 

 breaks, lack of association, and also the common intervention of macer- 

 ation, without apparent weathering (perhaps in part digestive, and 

 otherwise subaqueous) between death and burial. 



THE GIDLEY QUARRY AND ECOLOGICAL INCOMPATIBILITY 



Matthew (1930) has stated that "we should expect to find in a 

 single fossil quarry that the material of each genus represents a single 

 ecologic niche, or, if more than one, that they are quite distinct. We 

 should not, in other words, expect to find two or more closely related 

 species living together at the same time, within the same area, and 

 with the same habitat, causing their remains to be preserved together 

 in the same quarry . . . Either there would be two or more species 

 so widely dift'erent as to belong in obviously independent ecologic 

 niches, or else there would be one more or less variable species." 

 This is an application to paleontological data of the general principle 

 summed up by Cabrera (1932) as the Law of Ecologic Incompati- 

 bility in these words: "Las formas animales afines son ecologicamente 

 incompatibles, siendo su incompatibiiidad tanto mayor, cuanto mds 

 estrecha su afinidad." ^^ 



The Gidley Quarry fauna is ideally adapted to the application, on 

 one hand, and to the exemplification and corroboration, on the other, 

 of this law and of Matthew's remarks on the taxonomy of quarry 

 faunas. The species present in it were certainly contemporaneous, 

 and it is highly unlikely that any of the remains can have been brought 

 from a point so distant as to have inhabited distinctly different areas. 

 The general envu-onment was probably essentially the same for all, 

 although unquestionably it included distinct ecologic niches. It is 

 possible that deposition extended over a period of years and that there 

 was some seasonal or other periodic change in the species of the 



" I do net wish to claim for Cabrera a degree of originality that he disclaims for himself. Cabrera's law 

 has been recognized in various forms by many authors and for a long time, but as far as I know it has never 

 been more exactly explained and exemplified or placed more clearly on its true ecologic (not geographic) 

 basis than by Cabrera. 



