Comparing Cats: A Discussion of Similarities & Differences

[Balam]

(03-13-2021, 03:03 AM)tigerluver Wrote: The leopard and jaguar debate has brought some nice sources and information but please do not attack on another.

In trying to figure out if that large Persian leopard skull is of that weighed specimen, I noticed that can't be the case as the skull is from 1990 and the weighed specimen from 1997 going by the figure captions.

*This image is copyright of its original author

*This image is copyright of its original author

The excerpt is written unclearly but the figure captions seem to clarify.


Interspecific comparison of skull lengths to estimate weights is also filled with error and should not be used to determine which species is heavier. For instance, lions have proportionately longer skulls for their weight. Here is some data from Mazak et al. (see attachment) we can look at nonetheless to compare the jaguar and leopard:

  BM     CBL      Species
  47.3   219.8   Panthera onca CN5659 (♀)
  67.4   229.7   Panthera onca CN5660 (♂)
  51.5   222.4   Panthera onca CN5707 (♀)
  71.0   246.6   Panthera onca CN6221 (♂)
  56.7   188.2   Panthera pardus CN5661 (♀)
  57.9   210.1   Panthera pardus CN5662 (♂)
  44.5   199.7   Panthera pardus CN8462 (♂)


We should probably compare male to male and female to female, separately.

Average male jaguar has CBL of 238.15 mm and weight of 69.2 kg. Average male leopard has CBL of 204.9 mm and weight of 51.2 kg. We can now test by isometry which animal has a longer skull for its weight. If the below equation overestimates the larger skull, the shorter skulled animal has a proportionately shorter skull for mass (higher mass to skull length ratio) and vice versa.:

Jaguar predicted weight = (Jaguar skull length/Leopard skull length)^3 * Leopard weight
Jaguar predicted weight = (238.15 mm/204.9 mm)^3 * 51.2 kg
Jaguar predicted weight = 80.4 kg

Actual weight of the jaguars we had was 69.2 kg, so 16% overestimation. By this, the male leopard actually has a smaller skull for its weight and thus at equal skull lengths would actually be heavier than the male jaguar. 

For females, this math isn't necessary as the female jaguars have an average CBL of 221.1 mm and average weight of 49.4 kg while the single female leopard has a CBL 188.2 mm with weight of 56.7 kg. 

Just because the sample is so small here is a calculation pooling both genders:
Avg. jaguar CBL: 229.63 mm; Avg. weight: 59.3 kg
Avg. leopard CBL: 199.33 mm; Avg. weight: 53.3 kg

Jaguar predicted weight = (Jaguar skull length/Leopard skull length)^3 * Leopard weight
Jaguar predicted weight = (229.63 mm/199.33 mm)^3 * 53.3 kg
Jaguar predicted weight = 81.5 kg

The actual averaged weight of the jaguars we had was 59.3 kg, so 37% overestimation. By this extremely small sample size, the leopard actually has a smaller skull for its weight and thus at equal skull lengths would actually be heavier than the jaguar by quite a bit. The oddly heavy female leopard is the reason why the discrepancy jumps so much here.

Again the sample is extremely small and the specimens are captive, so I'm not confident in the results. I'd love to see if people have more body dimension to skull length data.

Interesting assessment, but as you mentioned the sample size is very small and may be prone to over/underestimations. These two samples are unrelated but may help us get a better idea of jaguar mass/skull correlation. I shared this table before from the skull measurements of Mexican jaguars from Cranial measurements of jaguars (Panthera onca) from the State of Oaxaca, Mexico

*This image is copyright of its original author

And we have the following weights for jaguars from adjacent regions in southern Mexico A morphological comparison of jaguars and pumas in southern Mexico:

*This image is copyright of its original author

 

Jaguars from southern Mexico are in theory smaller than the largest leopard population in record, the Persian leopard, but when you compare the data on skull width the smaller jaguars still average significantly larger than the leopard, Guate's data again:

*This image is copyright of its original author

Average weight:
Mexican jaguar (n:2) = 52.5 kg
Persian leopard (n: 21) = 65.8 kg

Average greatest skull length:
Mexican jaguar (n:5) = 262 mm
Persian leopard (n:30) = 245 mm

Average skull breadth:
Mexican jaguar (n:5) = 174.6 mm
Persian leopard (n:25) = 162 mm

Aspect ratio between skull length and width:
Mexican jaguar: 1.51:1, or 51% longer
Persian leopard: 1.51:1, the same ratio

In paper, this would suggest that both cats have similar proportions on skull size, but I posted this to highlight how deceptive comparing random samples between two animals can be when we then examined on an individual vs individual basis. The longest jaguar skull from the first sample was 288 mm, the same as the largest Persian leopard skull mentioned before, but their widths varied dramatically. The width of the jaguar was 196 (similar to the proportions on the Hoogestijn and Mondolfi data), while the leopard's was 181 mm. If we run the aspect ratio again:

Mexican jaguar: 1.47:1
Persian leopard: 1.59:1

Because both cats had the same skull length we can deduct the difference in percentages between the two, which results in the Persian leopard having a skull 12% longer proportionally than the jaguar's, while the jaguar is 8% wider proportionally. As you mentioned at the beginning of your post and as I said multiple times here before, lions and tigers display a similar disparity in skull dimensions with lions having proportionally longer skulls than tigers, tigers having wider skulls. A similar situation happens with jaguars and leopards, which is why we cannot assume that two very different species will yield the same body mass by going by skull length measurements when their proportions are considerably different.

Also notice how the Mexican jaguar had proportions consistent with the data for Pantanal/Llanos jaguars in length and width (290.5/194.2 - 289.6/194.1), while the leopard had a skull 8% longer in proportion to iwidth than the average on Guate's chart.

Finally, based on all the overwhelming data we have on the body mass of Persian leopards, the 4 different charts I posted here show maximal values of: 75, 78, 86, and 91 kg. Since the argument from the other side is that the largest leopards overlap in size with Pantanal jaguars per Hoogesteijn's data, then you would expect to see more leopards with weights of at least 100 kg, which are completely lacking from all this extensive sample.

My conclusion is that we cannot use specific skull measurements to try to gauge the size of an animal while using the proportions of animals of different species. There is simply no reason to believe that a leopard with a skull length of 288 mm will be the same size as an average Pantanal jaguar. Reply