PLEISTOCENE JAGUARS McCRADY ET AL. 507 



Examination of figure 97 shows that our fossils, while smaller, re- 

 semble P. atrox in the proportions of the humerus, third metacarpal, 

 femur, tibia, and third metatarsal — in other words, in most of the limb 

 proportions. The skull is relatively broader and the P * proportion- 

 ately much larger. The length of the skull and the length of the ulna 

 are reduced in about the same degree, having approximately the same 

 relation to each other as in atrox^ but being smaller in proportion to 

 the other parts of the body. 



The Recent jaguar skeleton used for comparison in these figures 

 (U.S.N.M. No. 49393) was chosen for its large size and is therefore not 

 typical in total dimension, but it is presumably normal in the relative 

 proportions of interest here. It has a skull as long as that of our Salt- 

 peter Cave fossil (our specimen No. 2), but all other parts of the 

 skeleton are smaller. The reduction is most conspicuous in the meta- 

 podials, which are proportionately shorter than in either of the fossil 

 forms.* 



The metapodials of these cats are equally distinctive in features 

 other than length. Figure 98 shows Simpson's original ratio diagram 

 comparing the second metatarsal in P. concolor^ P. onca, P. atrox, and 

 the fossil jaguar from Sweetwater, Tenn. (see Simpson, 1941b, p. 6, 

 fig. 3 ) , with one line added to represent our new material. It will be 

 seen that although Simpson's jaguar fossil was quite similar to the 

 Recent jaguar, ours differs from it in relative proportions as much as 

 does P. atrox, and in a rather similar way; so that ours resembles 



Regarding the interpretation of the graph, it should be noted that relative proportions 

 within the body of any one species (any one line on the graph) are not directly indicated, 

 but only how these relative proportions compare with those of the standard of reference. 

 Thus, if the maximum width of the head is shown displaced to the right and the length 

 of the ulnar to the left, this does not mean that the diameter of the head is greater than 

 the length of the forearm. It means that the head is broader in proportion to other 

 parts of the body in P. onca than it is in P. atrox. Similarly, if the length of P* is displaced 

 farther to the right than is the skull width, it does not mean that the length of this 

 tooth is greater than the width of the skull, but that it is proportionately more enlarged in 

 P. onca than is the width of the skull, when both of these are compared with the corre- 

 sponding proportions in P. atrox. This is a tremendously valuable kind of information 

 and it is better exhibited by this means than by any other we know. 



It should be noted also that the usefulness of ratio diagrams is completely destroyed 

 when isolated bones from different individuals are mixed together. To have any signifi- 

 cance at all, each curve in the graph must represent parts of a single individual, or of two 

 or more individuals definitely known to be of the same species and size, or well established 

 averages for parts of a single species. 



* One measurement indicated in Simpson's figure 10 is surprising. Though no actual 

 dimensions are given in the figure, the base line is said to be taken from Merriani and 

 Stock. The average length of the femur in P. atrox as given by these authors (1932, 

 p. 190) is 421.3 mm. On this scale the femur length indicated for P. onca would have 

 to be about 327 mm. We have not seen a jaguar femur anywhere near that size. The 

 largest we have measured is 272 mm. This was from a very large but not maximal 

 specimen. If the same proportions exist in the largest, the femur should not exceed about 

 282 mm. If we had used Simpson's figure we should have had to claim another distinction 

 between P. onca on the one hand and P. atrox and P. augusta on the other, but the curve 

 was left as found from our own measurements. 



