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Ancient Jaguars

tigerluver Offline
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#46

Please fill in the gaps in my memory, but the largest Pleistocene P. onca specimens are extrapolated from dentition, not skulls. That can mean two things. This cat had disproportionately large dentition for its skull, so dentition overestimated its size. Or, dentition are more common to find than skulls and thus better represent a wider size range within the species/population. 

The mandible fragment is a great find! The M1 is 21.1 mm, so it's right in the range of a modern jaguar. 

The excel file in this post details the dental record of the jaguar. The average M1 lengths are:

Extant P. onca: 20.17 mm (n=15, 17.4-22.5 mm)
P. o. augusta: 23.08 mm (n=14, 20.7-25.4 mm)
Pleistocene South America P. onca: 22.82 mm (n=15, 22-23.5 mm)

Based on isometric scaling between the aforementioned averages, P. o. augusta would be 1.5x the mass (1.144^3) of extant P. onca and Pleistocene South America P. onca would be 1.45x (1.131^3) the mass. Based on my studies of tigers and ancient lions, dentitions scale with positive allometry in comparison to skull length. I'd expect the same trend in jaguars. Therefore, I'd expect the mass difference to be greater as well.
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Jamaica KRA123 Offline
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#47

(12-21-2020, 11:13 AM)tigerluver Wrote: Please fill in the gaps in my memory, but the largest Pleistocene P. onca specimens are extrapolated from dentition, not skulls. That can mean two things. This cat had disproportionately large dentition for its skull, so dentition overestimated its size. Or, dentition are more common to find than skulls and thus better represent a wider size range within the species/population. 

The mandible fragment is a great find! The M1 is 21.1 mm, so it's right in the range of a modern jaguar. 

The excel file in this post details the dental record of the jaguar. The average M1 lengths are:

Extant P. onca: 20.17 mm (n=15, 17.4-22.5 mm)
P. o. augusta: 23.08 mm (n=14, 20.7-25.4 mm)
Pleistocene South America P. onca: 22.82 mm (n=15, 22-23.5 mm)

Based on isometric scaling between the aforementioned averages, P. o. augusta would be 1.5x the mass (1.144^3) of extant P. onca and Pleistocene South America P. onca would be 1.45x (1.131^3) the mass. Based on my studies of tigers and ancient lions, dentitions scale with positive allometry in comparison to skull length. I'd expect the same trend in jaguars. Therefore, I'd expect the mass difference to be greater as well.
Can you do this comparison while exclusively using Pantanal jaguars (as opposed to just modern ones) as the modern reference? That's what really needs to be done in order to properly investigate a potential size difference for augusta, since augusta is clearly larger than many modern Jaguar populations. Every study I've read over the years that compares skull measurements of augusta and the largest modern jaguars indicates that there isn't much difference in size in the measurements, as with the jaw fragment that Balam posted.
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tigerluver Offline
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#48

(12-21-2020, 11:47 AM)KRA123 Wrote:
(12-21-2020, 11:13 AM)tigerluver Wrote: Please fill in the gaps in my memory, but the largest Pleistocene P. onca specimens are extrapolated from dentition, not skulls. That can mean two things. This cat had disproportionately large dentition for its skull, so dentition overestimated its size. Or, dentition are more common to find than skulls and thus better represent a wider size range within the species/population. 

The mandible fragment is a great find! The M1 is 21.1 mm, so it's right in the range of a modern jaguar. 

The excel file in this post details the dental record of the jaguar. The average M1 lengths are:

Extant P. onca: 20.17 mm (n=15, 17.4-22.5 mm)
P. o. augusta: 23.08 mm (n=14, 20.7-25.4 mm)
Pleistocene South America P. onca: 22.82 mm (n=15, 22-23.5 mm)

Based on isometric scaling between the aforementioned averages, P. o. augusta would be 1.5x the mass (1.144^3) of extant P. onca and Pleistocene South America P. onca would be 1.45x (1.131^3) the mass. Based on my studies of tigers and ancient lions, dentitions scale with positive allometry in comparison to skull length. I'd expect the same trend in jaguars. Therefore, I'd expect the mass difference to be greater as well.
Can you do this comparison while exclusively using Pantanal jaguars (as opposed to just modern ones) as the modern reference? That's what really needs to be done in order to properly investigate a potential size difference for augusta, since augusta is clearly larger than many modern Jaguar populations. Every study I've read over the years that compares skull measurements of augusta and the largest modern jaguars indicates that there isn't much difference in size in the measurements, as with the jaw fragment that Balam posted.


How many skulls are out there? I’ll take a look at Merriam and Stock later to see if there is a difference in dental proportions.

Is there data available on the mandibles of extant Pantanal jaguars?
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Balam Offline
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#49

A couple of things to keep in mind when mentioning size overlap between skulls of Pleistocene and extant jaguar forms, in order to reach a solid conclusion one has to evaluate a multitude of skulls to see the size variation within one specific group. This way we can deduct which skulls may belong to females, subadult, and which belong to males. With Pantanal jaguars, we have an extensive dataset of skulls that show a maximum length of around 320 mm, by comparison, the ones from Pa. onca mesembrina approach 340 mm.

A great paper to read for those interested in looking into this further is Craniometric variation in Jaguar subspecies (Panthera onca) from Colombia, by Esteban Payan. Payan is Panthera's regional director for Latin America and the main authority in jaguar ecology in Colombia. He has taken over people like Rafael Hoogesteijn in conducting fieldwork around many Colombian and Brazilian sites to study current jaguar trends. His paper goes into depth by examining the craniometric variations of multiple jaguar populations in Colombia, treating several populations as possible subspecies to see if there was enough differentiation in size and shape of the skulls to substantiate a taxonomic revision. The conclusion from the paper is that there isn't, but nonetheless he reiterates that the skulls from the Pleistocene jaguar were significantly larger than any of the skulls he examined for the multiple supposed jaguar subspecies:



*This image is copyright of its original author

With all the fossil evidence there seems to be a widely accepted scientific consensus that Pa. onca augusta was simply larger than anything seen with extant jaguars today. But if that notion is to be challenged, we are going to need to bring forward multiple skulls to analyze and compare, and unfortunately, most of the skulls that are retained from this species are kept in museums that release very little public information about their sizes. 

The mandible from Mexico is, in my opinion, more than enough solid evidence to showcase that jaguars from the past were larger versions of what is found today, which makes perfect sense as they used to prey on megafauna whose biomass and quantity far surpassed what jaguars are able to feed on naturally these days. It's likely that the large sizes for populations like the Pantanal or Llanos simply represent individuals that didn't dwarf to the same degree as those from forested areas because they retained access to large amounts of mid-sized prey. Still, their sizes do not reach the maximum proportions of their Pleistocene counterparts.

One last point I'd like to make is that the basal species that gave rise to New World jaguars, P. gombaszoegensis was estimated to have been able to attain a mass very similar to the high estimates given for P. o mesembrina and augusta (I'm happy to go over the data for this species at a later time). The reduction in jaguar sizes is a recent phenomenon driven by the ecological constraints of the Holocene, historically they were significantly larger.
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tigerluver Offline
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#50
( This post was last modified: 12-22-2020, 11:50 PM by tigerluver )

Before I post in more detail, can anyone find the legend to the supplemental photos here?:

https://www.sciencedirect.com/science/ar...ub#sec0035

I feel like I used to have it/seen it...
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Balam Offline
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(12-22-2020, 11:49 PM)tigerluver Wrote: Before I post in more detail, can anyone find the legend to the supplemental photos here?:

https://www.sciencedirect.com/science/ar...ub#sec0035

I feel like I used to have it/seen it...

I'm busy at the moment but I will try find it and get back to you!
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Balam Offline
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#52

(12-22-2020, 11:49 PM)tigerluver Wrote: Before I post in more detail, can anyone find the legend to the supplemental photos here?:

https://www.sciencedirect.com/science/ar...ub#sec0035

I feel like I used to have it/seen it...

I tried looking on other scientific journal sites where the paper was published but the legend for those charts is not there either. The only explanation available is the fragmented skull which has been discussed before and I'm sure you're aware of:


*This image is copyright of its original author

Looking at the proportions of the skulls from the supplemented charts, my guess is that it is a collection of Pantherine skull from PumaP. leo, tigris, onca, atrox and perhaps spelaea as well, used to determine the anatomical differences mentioned in the paper to substantiate the proximity in traits the aforementioned skull had with P. leo and P. atrox, rather than P. onca. What do you think?


*This image is copyright of its original author

*This image is copyright of its original author
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Jamaica KRA123 Offline
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#53
( This post was last modified: 12-29-2020, 02:26 AM by KRA123 )

(12-21-2020, 12:08 PM)tigerluver Wrote:
(12-21-2020, 11:47 AM)KRA123 Wrote:
(12-21-2020, 11:13 AM)tigerluver Wrote: Please fill in the gaps in my memory, but the largest Pleistocene P. onca specimens are extrapolated from dentition, not skulls. That can mean two things. This cat had disproportionately large dentition for its skull, so dentition overestimated its size. Or, dentition are more common to find than skulls and thus better represent a wider size range within the species/population. 

The mandible fragment is a great find! The M1 is 21.1 mm, so it's right in the range of a modern jaguar. 

The excel file in this post details the dental record of the jaguar. The average M1 lengths are:

Extant P. onca: 20.17 mm (n=15, 17.4-22.5 mm)
P. o. augusta: 23.08 mm (n=14, 20.7-25.4 mm)
Pleistocene South America P. onca: 22.82 mm (n=15, 22-23.5 mm)

Based on isometric scaling between the aforementioned averages, P. o. augusta would be 1.5x the mass (1.144^3) of extant P. onca and Pleistocene South America P. onca would be 1.45x (1.131^3) the mass. Based on my studies of tigers and ancient lions, dentitions scale with positive allometry in comparison to skull length. I'd expect the same trend in jaguars. Therefore, I'd expect the mass difference to be greater as well.
Can you do this comparison while exclusively using Pantanal jaguars (as opposed to just modern ones) as the modern reference? That's what really needs to be done in order to properly investigate a potential size difference for augusta, since augusta is clearly larger than many modern Jaguar populations. Every study I've read over the years that compares skull measurements of augusta and the largest modern jaguars indicates that there isn't much difference in size in the measurements, as with the jaw fragment that Balam posted.


How many skulls are out there? I’ll take a look at Merriam and Stock later to see if there is a difference in dental proportions.

Is there data available on the mandibles of extant Pantanal jaguars?

I'm not sure how many skulls there are, but isolated skull elements like mandibles etc. can of course be compared between populations. If you look at my first post in this topic, I think I linked to a study that compared some augusta skull measurements with those of a large modern jaguar
*OK, I checked ant that's not the one, I'll have to look for the right one.
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tigerluver Offline
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#54
( This post was last modified: 12-30-2020, 01:06 PM by tigerluver )

I will try to get some clarification on that figure in the future.

For now, I've looked in Merriam and Stock (1932) and Mazak and Christiansen datasets (2011). The skulls in the latter have CBLs of 219.8-229.7 mm. The issue with the jaguar data from Merriam and Stock is that there is an extremely poor relationship between skull length and M1s (see pages 200-204). The largest skulls generally have M1s about the same length as the smaller skulls. Correlating the datasets, an M1 of the skulls in Mazak and Christiansen (2011) was probably around 18-20 mm. These specimens weighed 47.3-67.4 kg. If we take the high end of the skull length to M1 ratio and apply the multipliers in post #46, the average weight for P. o. augusta is (67.4 kg * 1.5) 101.1 kg. The largest specimen (M1 25.4 mm) would be 189 kg estimated very (and perhaps too) generously ((25.4 mm/18 mm)^3 * 67.4 kg). Pleistocene South American P. onca would have an average mass of (67.4 kg * 1.45) 97.73 kg. The largest specimen (M1 23.5 mm) would have weighed 150 kg ((23.5 mm/18 mm)^3 * 67.4 kg). The same generosity is applied here.

By the above analysis, @KRA123 is right these jaguars weren't really larger than the largest Pantanal specimens perhaps. Older literature has the issue of having small specimens represent extant taxa. These specimens are often below the average of the species. As such, often it is said extinct taxa are heftily larger than extant relatives, however this ends up not holding true as the comparative material was from smaller individuals. I could have missed the mark somewhat if the relationships had some allometry but unfortunately we don't have enough data available to run a regression. Moreover, more archaic cats generally had disproportionately large dentition. If this also applied to Pleistocene jaguars, then the estimates are probably inflated. The estimations may also be inflated just because I used the heaviest skull to m1 length ratio I could calculate.

If we compare the M1 of "P. o. mesembrina" to the average Pleistocene South American P. onca, the mass difference would be 2.3x ((30.2/22.82)^3). That seems much too out of the range for the jaguar populations. In extant cats, even the most exceptional of males are not over twice the weight of the average. Rereading Chimento and Agnolin (2017) (Wow, it has already been over three years since this was published...), pretty much all the "P. o. mesembrina" specimens are well out of the range of jaguars. Now I digress, but this would likely mean the lion made it to every continent except Australia and Antarctica, absolutely breathtaking.
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Balam Offline
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#55
( This post was last modified: 04-29-2021, 04:40 AM by Balam )

@tigerluver first of all, great job in the equation for the allometric predictions for Pleistocene jaguars based on dental remains as they compare to extant remains. Unsurprisingly, however, I still have to push against the conclusion for you and KRA's point in regards to relative mass for Pleistocene jaguar forms and their closeness to large extant jaguars.

To begin, the specimen gathered from Mexico (Ramoni et al, 2020) shows c1 value greater in length and width than what's shown for average extant jaguars, despite M1 and c1 length values being in the range of a large extant male:


*This image is copyright of its original author


*This image is copyright of its original author

It's worth pointing out that the specimens for Soyatlan and San Josecito all represent Pleistocene jaguar forms from Mexico, placing it closer to an extant male lion and the lower values were seen for American lions. Now, according to the analysis made for this particular mandible, the proportions of the teeth and their placement in the bone all match the characteristics of P. onca, and not P. atrox. Hence the claim in the article that the values for this particular fragment are much greater than that of any extant jaguar, while simultaneously matching the proportions and shape expected for P. onca, which substantiate the claim that these fossils belong to a large jaguar, largest than what's seen with extant animals from Mexico at least.

The article: The assessment of size in fossil Felidae (Turner & Regan, 2002) offers, in my opinion, great insight into how easy it is to miscalculate the mass of an animal based on dental fragments solely, as their regression analysis performed on jaguars (could not be more perfect for this discussion) shows a direct correlation between mass and skull length, but the correlation becomes random the moment the values are plotted in a correlation between dental, mass, and body length values. The used the data by Hoogesteijn and Mondolfi we've all seen before:


*This image is copyright of its original author

*This image is copyright of its original author

*This image is copyright of its original author


*This image is copyright of its original author

When comparing to other species, the authors concluded that it is futile to use interspecific dental fragments without having a clear regression analysis on the correlation between dental remains and overall skull dimensions, to assess if any direct link exists between dental dimension, skull proportions, and overall mass or frame of the species in question:


*This image is copyright of its original author



Now, if we use the data from the mandible form Mexico and we compare it to the data from Hoogesteijn and Mondolfi, what we get are the values from a large jaguar within the range of what is seen in very large extant males, but likewise, in terms of size proportions, the lower canines do overlap in size with what is seen in some extant male lions and the smaller ranges for American lions. This could mean that the specimen from Mexico was indeed much greater in size than what is seen for extant Mexican jaguars, but within the limits of large South American floodplain jaguars, as you pointed out before. 
Here are the skull measurements for extant jaguars in Oaxaca, Mexico, an area of Mexico Hoogesteijn and Mondolfi didn't include in their study, from Cranial measurements of jaguars (Panthera onca) from the State of Oaxaca, Mexico (Lavariega & Salas):


*This image is copyright of its original author

I'm sure the values for the skull of the Pleistocene jaw from Soyatlan would have been much greater than the ranges shown here, but who knows how it would compare with the length and overall size for skulls belonging to Pantanal, Llanos, Chaco, and other jaguars.

One factor to take into account when comparing this data is that we do not know the exact sex of the specimen IGM 9518, or its age. Needless to say that if this represents an adult male, then yes, the values for this specimen of P. o. augusta are in line with large extant jaguars. But if the skull in fact belongs to a female or a sub-adult male, then the size potential for this particular species as it's expressed by this mandible would be much greater than anything seen with extant jaguars.

Now, one last point I'd like to make to substantiate my claim that the data for fossil jaguars is consistently larger than what is seen with modern jaguars, I'd like to go over the data we have for the Eurasian jaguar, P. gombaszogensis. The study The Panthera gombaszogensis story: the contribution of the Château Breccia (Saône-et-Loire, Burgundy, France) by Argant et al. Goes into detail on the craniometric and dental values for this species and how it compares to modern jaguars.
The skull studied also showed values that could be placed within modern jaguars, without knowing the sex and age of the specimen either. The data is very extensive and long and can't be fitted here but is easily accessible in the article for anyone interested. Nonetheless, the authors concluded that the size of the individual in question must have been larger than extant jaguar forms thanks to the measurements of skeletal remains beyond the skull:


*This image is copyright of its original author

I do believe they likely used smaller populations of jaguars to arrive at that conclusion as the largest extant male show larger values for overall skull size than what is seen in the specimen they analyzed.
What I did find interesting are the quoted values and averages predicted for the weight of fossil Old-World jaguars based on what seems unpublished data:



*This image is copyright of its original author

*This image is copyright of its original author

We can compare these values with what is shown for extant males from the Pantanal in recent times, per our table:


*This image is copyright of its original author

My conclusion from all this is that there does seem to be an overlap between the largest extant jaguars and extinct Pliocene and Pleistocene forms, per yours and KRA's point, but it also seems clear to me that in regards to averages and absolute values the ranges for fossil forms were significantly larger than what is seen with living jaguars. This can be explained by the availability of larger prey items during prehistoric times, which allowed the potential in jaguars to be greater in terms of overall mass, while the largest living populations may show similar values with outlier and large males who have access to plenty of prey and a strong genetic background.

Hopefully, in the future we can gain access to a larger sample of complete skulls and skeletons for fossil jaguars to best assess how they directly compare to living jaguars.
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tigerluver Offline
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#56
( This post was last modified: 12-30-2020, 11:36 PM by tigerluver )

Absolutely excellent post @Balam.

To open, I think we have been aware that dentition are very poor predictors. The issue we have at hand is that it is all we have for these ancient jaguars and as @KRA123 noted the skulls we have been able to pinpoint don't show animals larger than extant jaguars. As such, we have to look at the dentition which have the larger specimens. A quick note, the formulas above are isometric (scale factor of 3). We couldn't check for allometry as the data is no available. I could use my tiger data as a model for the scale factor but when a skull I measured of ~380 mm had an M1 smaller than a female's, you can imagine how useless I'd find the regression.

On IGM 9518: Good note that the canine is larger. However, we cannot choose the canine over the M1 and vice versa in terms of which is the better predictor. From that nice table, both of their R^2 are poor with only a mild correlation. However, measurements of the actual mandibular ramus itself are quite strong in correlation to mandible length, and by extension skull length. I really wish I had some of my own jaguar data but I only measured lion and tiger skulls for a while now and missed out. So I'll open up Merriam and Stock (1932). So we have the height at M1 for IGM 9518 which is 31.2 mm. This seems to be smaller than most of the males in Merriam and Stock (1932). We can't exactly compare the other ramus height measurement as for IGM 9518 it's taken at the p3, while Merriam and Stock (1932) measured at the p4. The p3 height is generally greater than the p4, so as such the anterior height of the mandible is also smaller than the male extant jaguars in Merriam and Stock (1932). To be frank, this shows that IGM 9518 had disproportionately large dentition and also reemphasizes how poor dentition are at predicting size.

One last thing, I still haven't identified this source. Anyone know?:


*This image is copyright of its original author


Will have to get the other discussion points later.
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Balam Offline
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#57
( This post was last modified: 04-29-2021, 04:41 AM by Balam )

This study hasn't been posted here but a paper that studied the genetic relationship between extinct Pleistocene Patagonian taxa through phylogenetic reconstructions based on mitochondrial DNA concluded that P. o. mesembrina was well within the genetic markers of P. onca, not P. atrox. The likelihood that Chimento and Agnolin's (2017) paper did in fact relate to P. atrox becomes even less substantiated considering that the genetic data from this species is completely lacking from the area. The cave paintings do not depict lion-like creatures (but they do depict spotted felids), and the remains of P. atrox have not been found in other South American or Central American sites southern from Mexico to infer a proper migration, as we do have with other species. 

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation, by Metcalf et al (2016):


*This image is copyright of its original author

*This image is copyright of its original author

While the modern jaguar forms a monophyletic species, during the Pleistocene P. o. mesembrina could be genetically distinguished as a different subspecies, but not being different enough to be classified as a distinct species altogether. This is why using craniometric data from modern jaguars to conclude that P. o. mesembrina belonged to a different species is flawed, as the morphology of P. onca would vary from this other subspecies, and the environmental factors that could've contributed to the greater size on the Pleistocene form (such a larger prey availability and biomass during) are not present in the native ranges of extant jaguars. These ecological differences are key in distinguishing the morphological differences the two subspecies depict.

*This image is copyright of its original author

From the supplementary data:


*This image is copyright of its original author

*This image is copyright of its original author

If we are to take Chimento and Angolin's work with a degree of plausibility, we should also take into consideration other data that points towards the contrary with stronger DNA samples as opposed to ambiguous skull markers. The idea that P. atrox made it as far as the southern tip of the Patagonia is at best very dubious.

Furthermore, I found their work to lose credibility considering the degree of speculation in which they went to describe the supposed appearance of "P. atrox" based on factors that may have not been related at all, such as fur found on the caves which led them to believe it had a "reddish" coating, something that we do not see i the frozen remains of cave lion cubs.
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Australia Richardrli Offline
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#58

That's interesting, it would indicate these Late Pleistocene jaguars were notably different enough from all extant jaguars while the pumas even then were quite similar to modern ones.
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tigerluver Offline
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(04-15-2021, 04:54 AM)Balam Wrote: This study hasn't been posted here but a paper that studied the genetic relationship between extinct Pleistocene Patagonian taxa through phylogenetic reconstructions based on mitochondrial DNA concluded that P. o. mesembrina was well within the genetic markers of P. onca, not P. atrox. The likelihood that Chimento and Agnolin's (2017) paper did in fact relate to P. atrox becomes even less substantiated considering that the genetic data from this species is completely lacking from the area. The cave paintings do not depict lion-like creatures (but they do depict spotted felids), and the remains of P. atrox have not been found in other South American or Central American sites southern from Mexico to infer a proper migration, as we do have with other species. 

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation, by Metcalf et al (2016):


*This image is copyright of its original author

*This image is copyright of its original author

While the modern jaguar forms a monophyletic species, during the Pleistocene P. o. mesembrina could be genetically distinguished as a different subspecies, but not being different enough to be classified as a distinct species altogether. This is why using craniometric data from modern jaguars to rule out the possibility of P. o. mesembrina belonging to a different species is flawed, as the morphology of P. onca would vary from this other subspecies, and the environmental factors that could've contributed to the greater size on the Pleistocene form (such a larger prey availability and biomass during) are not present in the native ranges of extant jaguars. These ecological differences are key in distinguishing the morphological differences the two subspecies depict.

*This image is copyright of its original author

From the supplementary data:


*This image is copyright of its original author

*This image is copyright of its original author

If we are to take Chimento and Angolin's work with a degree of plausibility, we should also take into consideration other data that points towards the contrary with stronger DNA samples as opposed to ambiguous skull markers. The idea that P. atrox made it as far as the southern tip of the Patagonia is at best very dubious.

Furthermore, I found their work to lose credibility considering the degree of speculation in which they went to describe the supposed appearance of "P. atrox" based on factors that may have not been related at all, such as fur found on the caves which led them to believe it had a "reddish" coating, something that we do not see i the frozen remains of cave lion cubs.


Sorry I got to this so late. Great paper! 

I was comparing the datasets and they are from the same sites mentioned by Chimento and Agnolin (2017). The lack of P. atrox in the same can obviously mean there was no P. atrox or that the frequency of P. atrox was much less and thus it wasn't represented in the small random sample. The sample size is decent at 17.

I could not find it so I was wondering if you were able to find a divergence date between P. onca and P. onca mesembrina in the study? It would be helpful in our reconstructions.

I also have the legends for the excellent comparative photos in Chimento and Agnolin (2017). A is of course the "P. onca mesembrina" skull. B-D is P. leo, E is P. atrox, F and R-Y are extant P. onca, G-H are the fossil P. onca.

Here are the figures again:

*This image is copyright of its original author

*This image is copyright of its original author


From these comparative photos, Chimento and Agnolin (2017) are correct in the assertion that the incisive foramina of the skull in question are visible in superior view. Extant jaguars do not have this trait and would be solid evidence against the mystery skull being of the extant P. onca form. Even in the fossil P. onca we see the incisive foramina are not visible from the superior view. They also assert that the snout is indistinguishable from P. leo/P. atrox. To me, the rostrum looks more stout then pretty much all the other specimens in the photo except maybe P. spelaea (J) and the fossil P. onca (G and H specifically). Stoutness is however a more jaguar-like trait. I will note that the damage to the snout also makes it harder to ascertain the true stoutness of the rostrum.

It could be fair to say the skull does not group well with comparative specimens as its traits are a unique combination. If "P. onca mesembrina" is a genetically distinct taxon related to extant P. onca, this could make sense. I also want to highlight a new species of P. balamoides in this discussion. To quote, "Panthera balamoides sp. nov. combines characters of smilodontids and Panthera, with more similarities to Panthera onca." This asks the question if the "P. onca mesembrina" skull and P. balamoides are of the same species.
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Balam Offline
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(04-26-2021, 12:57 AM)tigerluver Wrote:
(04-15-2021, 04:54 AM)Balam Wrote: This study hasn't been posted here but a paper that studied the genetic relationship between extinct Pleistocene Patagonian taxa through phylogenetic reconstructions based on mitochondrial DNA concluded that P. o. mesembrina was well within the genetic markers of P. onca, not P. atrox. The likelihood that Chimento and Agnolin's (2017) paper did in fact relate to P. atrox becomes even less substantiated considering that the genetic data from this species is completely lacking from the area. The cave paintings do not depict lion-like creatures (but they do depict spotted felids), and the remains of P. atrox have not been found in other South American or Central American sites southern from Mexico to infer a proper migration, as we do have with other species. 

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation, by Metcalf et al (2016):


*This image is copyright of its original author

*This image is copyright of its original author

While the modern jaguar forms a monophyletic species, during the Pleistocene P. o. mesembrina could be genetically distinguished as a different subspecies, but not being different enough to be classified as a distinct species altogether. This is why using craniometric data from modern jaguars to rule out the possibility of P. o. mesembrina belonging to a different species is flawed, as the morphology of P. onca would vary from this other subspecies, and the environmental factors that could've contributed to the greater size on the Pleistocene form (such a larger prey availability and biomass during) are not present in the native ranges of extant jaguars. These ecological differences are key in distinguishing the morphological differences the two subspecies depict.

*This image is copyright of its original author

From the supplementary data:


*This image is copyright of its original author

*This image is copyright of its original author

If we are to take Chimento and Angolin's work with a degree of plausibility, we should also take into consideration other data that points towards the contrary with stronger DNA samples as opposed to ambiguous skull markers. The idea that P. atrox made it as far as the southern tip of the Patagonia is at best very dubious.

Furthermore, I found their work to lose credibility considering the degree of speculation in which they went to describe the supposed appearance of "P. atrox" based on factors that may have not been related at all, such as fur found on the caves which led them to believe it had a "reddish" coating, something that we do not see i the frozen remains of cave lion cubs.


Sorry I got to this so late. Great paper! 

I was comparing the datasets and they are from the same sites mentioned by Chimento and Agnolin (2017). The lack of P. atrox in the same can obviously mean there was no P. atrox or that the frequency of P. atrox was much less and thus it wasn't represented in the small random sample. The sample size is decent at 17.

I could not find it so I was wondering if you were able to find a divergence date between P. onca and P. onca mesembrina in the study? It would be helpful in our reconstructions.

I also have the legends for the excellent comparative photos in Chimento and Agnolin (2017). A is of course the "P. onca mesembrina" skull. B-D is P. leo, E is P. atrox, F and R-Y are extant P. onca, G-H are the fossil P. onca.

Here are the figures again:

*This image is copyright of its original author

*This image is copyright of its original author


From these comparative photos, Chimento and Agnolin (2017) are correct in the assertion that the incisive foramina of the skull in question are visible in superior view. Extant jaguars do not have this trait and would be solid evidence against the mystery skull being of the extant P. onca form. Even in the fossil P. onca we see the incisive foramina are not visible from the superior view. They also assert that the snout is indistinguishable from P. leo/P. atrox. To me, the rostrum looks more stout then pretty much all the other specimens in the photo except maybe P. spelaea (J) and the fossil P. onca (G and H specifically). Stoutness is however a more jaguar-like trait. I will note that the damage to the snout also makes it harder to ascertain the true stoutness of the rostrum.

It could be fair to say the skull does not group well with comparative specimens as its traits are a unique combination. If "P. onca mesembrina" is a genetically distinct taxon related to extant P. onca, this could make sense. I also want to highlight a new species of P. balamoides in this discussion. To quote, "Panthera balamoides sp. nov. combines characters of smilodontids and Panthera, with more similarities to Panthera onca." This asks the question if the "P. onca mesembrina" skull and P. balamoides are of the same species.

Quote:I was comparing the datasets and they are from the same sites mentioned by Chimento and Agnolin (2017). The lack of P. atrox in the same can obviously mean there was no P. atrox or that the frequency of P. atrox was much less and thus it wasn't represented in the small random sample. The sample size is decent at 17.

Yes, most of the analyzed remains come overwhelmingly from the Mylodon cave which was the site used in Chimento and Agnolin's study. This is really good because it keeps us from inferring if the two genetic data gathered from Metcalf et al. directly correlates with the 2017 paper.

Quote:I could not find it so I was wondering if you were able to find a divergence date between P. onca and P. onca mesembrina in the study? It would be helpful in our reconstructions.

Unfortunately the study didn't mention the divergence date between both subspecies beyond their genetic proximity and how they relate to other pantherines. Perhaps this data will come along in further studies in the future. My guess is that the genetic split between P. onca and P. onca mesembrina would be between 300,000 at most to 150,000, if we use similar evolutionary patterns based on the relationships between the subspecies of P. leo.


Quote:From these comparative photos, Chimento and Agnolin (2017) are correct in the assertion that the incisive foramina of the skull in question are visible in superior view. Extant jaguars do not have this trait and would be solid evidence against the mystery skull being of the extant P. onca form. Even in the fossil P. onca we see the incisive foramina are not visible from the superior view. They also assert that the snout is indistinguishable from P. leo/P. atrox. To me, the rostrum looks more stout then pretty much all the other specimens in the photo except maybe P. spelaea (J) and the fossil P. onca (G and H specifically). Stoutness is however a more jaguar-like trait. I will note that the damage to the snout also makes it harder to ascertain the true stoutness of the rostrum.
 
I think this area becomes more tricky to assess and where most of the controversy centers around, hence my dissatisfaction with Chimento and Agnolin's work relying almost entirely on ambiguous skull markers to make very bold claims. While the incisive foramina are certainly visible on the P. onca mesembrina skull, the conclusion from the 2017 study concerning the muzzle is in my opinion completely erroneous. As you said the snout in P. onca mesembrina is more stout than in P. leo or P. atrox and almost resembles perfectly the H skull belonging to fossil P. onca. Furthermore, while the skull for P. onca mesembrina is not complete, one can tell from looking at the beginning of the zygoma (and based on the rendition performed in the study itself) that it would've been significantly wider than the zygomatic arches of P. leo and P. atrox. In fact, the difference between P. onca mesembrina and P. atrox is this regard is the most pronounced in the entire sample, while it matches almost perfectly with the remains of fossil P. onca, IMO. 

Quote:It could be fair to say the skull does not group well with comparative specimens as its traits are a unique combination. If "P. onca mesembrina" is a genetically distinct taxon related to extant P. onca, this could make sense. I also want to highlight a new species of P. balamoides in this discussion. To quote, "Panthera balamoides sp. nov. combines characters of smilodontids and Panthera, with more similarities to Panthera onca." This asks the question if the "P. onca mesembrina" skull and P. balamoides are of the same species.

Personally, I think that the traits present in the P. onca mesembrina skull align more closely to P. onca than any other pantherine, granted that some differences are appreciated but this could be explained by morphological adaptations that evolved from the basal P. onca as the mitochondrial data has concluded them to be different subspecies. 

In regards to "P. balamoides", this was a potential species I was very interested in some time ago as it would've expanded the range of the pantherine felids in the New World considering many people thought this was a different species from P. onca, P. atrox or P. spelaea. However recent studies strongly point towards the possibility that these remain in fact belong to the ursid Arcotherium and it was never a true felid after all. See Yucatán carnivorans shed light on the Great American Biotic Interchange, by Schubert et al. (2019).

Another layer that puts into question the existence of P. atrox in the Patagonia is the lack of cave paintings associated with this taxon in contrast to jaguar paintings. We discussed the ones from the Mylodon cave some time ago, but here's some more from adjacent areas. These paintings were described in the paper La Cueva de los Yaguaretés by Ramirez in 2002 from the Santa Cruz province in the Argentine Patagonia:


*This image is copyright of its original author

And likewise from Santa Cruz Arte rupestre pleistoceno de Santa Cruz, Patagonia Argentina, Paunero (2012):


*This image is copyright of its original author

*This image is copyright of its original author

Granted that we do not have radiocarbon dating for these specific rock paintings which makes it hard to assess their temporal proximity to P. onca mesembrina and Patagonian post-glacial P. onca, but the depictions are consistent with the cave paintings described by Chimento and Agnolin, with a spotted cat being the common denominator. We know from cave paintings in Europe that local human tribes did not shy away from describing the lion in their art. It is likely that they saw them as extremely important species and held plenty of reverence to them, and we should expect the same phenomenon with human settlements that utilized similar art methods in caves to describe the world around them, as was the case in the Patagonia. Yet we get a complete absence of lion paintings from this region in contrast to the jaguar, this leads me to believe that the relationship between local Patagonian tribes and the jaguar was similar to that of Europeans with cave lions.

We know that Chimento and Agnolin have in their position fur enclaved to a claw and a patch of skin, it would be interesting if they could analyze the genetic composition of those fragments of fur to determine what species they belonged to, rather than liberally guessing. My guess is that they would come back matching Smilodon populator. If further studies like these are not performed by them my suspicions that the conclusions on the supposed presence of P. atrox in the Patagonia by them were simply rushed and may have been driven by bias (wanting to have the presence of P. atrox in South America). I believe that the lack of DNA from P. atrox from Metcalf et al. is a strong enough deterrent to at least put into question the veracity of the claims made in the other paper. 

As it is often said extraordinary claims require extraordinary evidence and Chimento and Agnolin have yet to provide us that.
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