508 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



P. atrox more than it does P. onca. None of these is at all similar to the 

 puma, so we have not included concolor in other figures.® 



One of the features in which P. augusta is most dissimilar to modem 

 jaguars is the ratio of width of muzzle to condylobasal length of skull. 



-.24 -.20 -16 -12 -.08 -.04 .04 



a 





+ P. atrox 



I I Q P. augusta 



^ ^ X P. onca 



_Length of Fourth 

 Upper Premolar 

 . Skul/ width 



Lengih of 



hlumerus 



Skull length 



. Length of Tibia 



.Length of Femur 



Length of Third 

 Metatarsal 

 . Length of Third 

 Metacarpal 



Length of Ulna 



Figure 100. — Ratio graph with the order of structures changed to facilitate comparison 

 of Panthera atrox and P. onca. 



In our Saltpeter Cave fossil this ratio has the value 0.347. In a series 

 of jaguars in the United States National Museum it varies from 0.297 

 to 0.324 with an average value of 0.309 and a standard deviation of 

 ±0.008. The departure of the ratio in the fossil from the mean for 

 the modern jaguar is 4.75o-. The odds against such a variation oc- 

 curring in any known subspecies of jaguar are considerably greater 

 than 15,000 to 1. On the other hand, P. augusta and P. atrox resemble 

 each other sufficiently closely in this ratio to be inseparable by refer- 

 ence to it. P. atrox averages only 0.328 ±0.0129. The P. augusta 

 specimen shows a deviation of 0.019, which is only about 1.46 times 

 the standard error and cannot be taken seriously. 



Furthermore, P. augusta is sharply distinct from P. onca in several 

 other features not previously mentioned, and in these it resembles 

 P. atrox so closely as to be inseparable with reference to them. Thus, 

 the inflation of the frontal region in P. augusta and P. atrox is quite 



' The Sweetwater material, however, is not all from one individual. The teeth will not 

 occlude properly. The lower jaw Is decidedly too big for the upper jaw. So at least two 

 Individuals are involved, and possibly more. Presumably the mandible belongs to the 

 same species as do our fossils, but we are not at all sure about the second metatarsal. 

 Since the Sweetwater bones are quite definitely not from one individual, there Is no com- 

 pelling a priori reason for accepting them as one species. We shall not pursue this puzzle 

 any further in the absence of more material, but the possibility should be borne In mind 

 that there may have existed in Pleistocene times both a true jaguar with the shortened 

 and characteristic metapodials, and another cat, P. augusta, which was more lilce P. atrox 

 in these and several other parts, but only slightly larger than P. onca. More associated 

 skeletons will be needed to settle this point. 



