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(05-28-2022, 03:39 AM)jrocks Wrote: Hi Guate, i was just curious about if the 16.07 inch skull were to have its weight calculated the same way that 436 kg was calculated for 15.4 inch skull, how much would it have weighed
jrocks
Apart from all the issues with that formula, the main problem is that the formula of Van Valkenburgn (1990) use the Condylobasal length, not the Greatest length (an error that many people made when they use it), and as you already probably know, we don't know the CBL of the giant skull. We can speculate based in the known specimens, but it will be a calculation over an asumption.
This is the formula, by the way, using only felids: log mass = 3.11 * log CBL - 5.38
Do you mean to say that the 15.4 inch was the CBL while the 16.04 inch was the GSL?
And can you please tell me the source of the CBL regression equation which you mentioned?
no they are 2 separate skulls, one is the one found uruguay which had a GSL of 15.4 inches and its CBL was 14.9 inches, the other is called smilodon bonaeresis 10-1 and its GSL is 16.07 inches, however its CBL isnt known
Okay, then you can use isometry but the result will be unreliable because of using only a single isometric calculation.
Nevertheless, if you isometrically scale a Populator specimen of 15.4 inches which weight 436kg then a specimen of 16.04 inches would be 495kg assuming isometry within both specimens.
BUT this result is *not* reliable because we just used a single calculation and making calculation using only a single dimension or single calculation often gives wrong weight estimates.
One more reason this is unreliable is because as @GuateGojira stated, the 436kg estimate itself may be inaccurate.
If you can find a regression equation between weights and GSL then you may be able to get an actually reliable estimate (possibly an equation specifically made for Smilodon Populators)
You can use the same relation between GSL and CBL as you have in the smaller skull and then use that to estimate the weight from Guate’s formula but like Guate said, that would be all guesswork and that will also become unreliable in that sense.
dang with that isometry formula it can weigh a crazy amount, as for the 15.4 inch skull does guat think 436 kg is an overestimate or an underestimate, also is it known how much smilodon bonaerensis 10-1 weighs as its full skeleton is completely preserved
I’ll have to check to make sure but probably an overestimate if you estimate this one with the Christiansen & Harris estimate as reference.
And as far as I remember I think I had seen a weight estimate for that particular fully preserved specimen but I don’t remember an exact number so if I see it, I’ll tell
oh shooot my bad, i meant say smilodon bonaerensis 46, not bonaerensis 10-1, bonaerensis 46 is the one with a full skeleton not 10-1
The large "Smilodon bonaerensis 10-1" with a GSL of 408.4 GSL but no CBL, and the Uruguay big one MNHN-P 957 with a GSL of 392 mm in GLS and 379 in CBL.
Honestly, the two skulls are about the same size (just less than 1.7 cm of difference) that they are virtualy of the same size and could be of the same weight.
The formula was created by the Dr Blaire Van Valkenburgh and is in the document of 1990 "Skeletal and dental predictors of body mass in carnivores" (chapter 10), in the book "Body Size in Mammalian Paleobiology: Estimation and Biological Implications".
The large "Smilodon bonaerensis 10-1" with a GSL of 408.4 GSL but no CBL, and the Uruguay big one MNHN-P 957 with a GSL of 392 mm in GLS and 379 in CBL.
Honestly, the two skulls are about the same size (just less than 1.7 cm of difference) that they are virtualy of the same size and could be of the same weight.
The formula was created by the Dr Blaire Van Valkenburgh and is in the document of 1990 "Skeletal and dental predictors of body mass in carnivores" (chapter 10), in the book "Body Size in Mammalian Paleobiology: Estimation and Biological Implications".
Exactly what I have in mind. When there is a large difference between the size of two skulls of the same species then it’s likely that the bigger skull would belong to a bigger specimen overall but when the difference between the two skulls is very little then it is more likely that the two specimens may have been pretty much the same size with one of them just having a bigger skull than the other.
This is exactly why isometry is best used when there is at least some amount of size difference but when the difference is very little between the two bones then isometry is not ideal, especially if you are using only a single measurement (and hence just a single isometric equation) for the bones.
And this is exactly why I said the result is unreliable.
@jrocks Like I said I would be inclined to say that those two specimens were likely not isometric just from slightly different skull sizes.
We would of course need more data but until we have it, I would suggest we consider the maximum weight of Smilodon Populators just slightly above 400kg and I don’t think we can say with enough certainty that the specimens with those skulls were any more bigger than that until we see something more concrete.
05-30-2022, 09:52 PM( This post was last modified: 05-30-2022, 10:05 PM by LonePredator )
Also @GuateGojira do you have some compilation of data on bone measurements and weight estimates for any of the prehistoric felids? Because with enough amount of data of bone measurement and weight estimate pairs, we could derive a regression equation and make much more precise weight estimates on our own without needing to rely on isometric estimation.
(05-30-2022, 09:52 PM)LonePredator Wrote: Also @GuateGojira do you have some compilation of data on bone measurements and weight estimates for any of the prehistoric felids? Because with enough amount of data of bone measurement and weight estimate pairs, we could derive a regression equation and make much more precise weight estimates on our own without needing to rely on isometric estimation.
Not a compilation, but certainly some bone meausrements and weights estimations, but are scatered in several documents.
05-31-2022, 05:33 PM( This post was last modified: 05-31-2022, 05:42 PM by LonePredator )
(05-30-2022, 11:35 PM)GuateGojira Wrote:
(05-30-2022, 09:52 PM)LonePredator Wrote: Also @GuateGojira do you have some compilation of data on bone measurements and weight estimates for any of the prehistoric felids? Because with enough amount of data of bone measurement and weight estimate pairs, we could derive a regression equation and make much more precise weight estimates on our own without needing to rely on isometric estimation.
Not a compilation, but certainly some bone meausrements and weights estimations, but are scatered in several documents.
Is it feasible to compile them all and is there enough of it? Do you think there is enough of the data to make large enough sets of ‘weight estimate/bone measurement’ pairs separately for each species?
The CBL formula from Valkenburg you provided was made for all kinds of felids, right? And I am sure he made this for all felids because he did not have enough number of skulls to make separate regression equations for each separate felid species.
And because of this reason his formula may not be precise enough either and the weight estimate could have a large deviation from the actual weight if you use Valkenburg’s formula.
(05-31-2022, 05:33 PM)LonePredator Wrote: Is it feasible to compile them all and is there enough of it? Do you think there is enough of the data to make large enough sets of ‘weight estimate/bone measurement’ pairs separately for each species?
The CBL formula from Valkenburg you provided was made for all kinds of felids, right? And I am sure he made this for all felids because he did not have enough number of skulls to make separate regression equations for each separate felid species.
And because of this reason his formula may not be precise enough either and the weight estimate could have a large deviation from the actual weight if you use Valkenburg’s formula.
It will be very dificult, but I will try to compite it.
The formula of Dr Van Valkeburgh, from cats and from overall carnivores, is made with values in litterature, not real measurements and weights, in fact she present the values (in log values) in the document, so we can even check what values she used. The problem is that even when she do that, we know that the relation of skull with body size/weight is not the same in all the felids (ej. tigers and lions) so this create the ilusion that the bigger the skull, bigger the mass, which is not correct and depend in the variations on the species.
(05-31-2022, 05:33 PM)LonePredator Wrote: Is it feasible to compile them all and is there enough of it? Do you think there is enough of the data to make large enough sets of ‘weight estimate/bone measurement’ pairs separately for each species?
The CBL formula from Valkenburg you provided was made for all kinds of felids, right? And I am sure he made this for all felids because he did not have enough number of skulls to make separate regression equations for each separate felid species.
And because of this reason his formula may not be precise enough either and the weight estimate could have a large deviation from the actual weight if you use Valkenburg’s formula.
It will be very dificult, but I will try to compite it.
The formula of Dr Van Valkeburgh, from cats and from overall carnivores, is made with values in litterature, not real measurements and weights, in fact she present the values (in log values) in the document, so we can even check what values she used. The problem is that even when she do that, we know that the relation of skull with body size/weight is not the same in all the felids (ej. tigers and lions) so this create the ilusion that the bigger the skull, bigger the mass, which is not correct and depend in the variations on the species.
Yes, I agree completely. It’s not possible to estimate all felids with just a single formula because they are so different in morphology. We definitely need separate formulas for each felid species and if you are going to estimate one felid by using others as surrogates then you must do something like the Christiansen and Harris method.
The Christiansen and Harris method took multiple different measurements of the same bone and this allowed them to measure the drastic allometric variations within different felid species. In my mind, the Christiansen and Harris method is the most precise estimation for the Smilodon Populator till date.
If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Hence, the Christiansen and Harris formula is the best one till date especially for a species like Smilodon Populator for which no similar shape surrogate exists in the modern day.
06-01-2022, 08:46 PM( This post was last modified: 06-01-2022, 08:47 PM by GuateGojira )
(06-01-2022, 10:15 AM)LonePredator Wrote: If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Actually it will be a gross overestimation, and here is an example, using the biggest CBL from the Panthera cats, taken by scientists, here you can see the weights calculated (in red) and at the right the maximum weights actually recorded (in blue):
Formula use: log mass = 3.11 * log CBL - 5.38 - Van Valkeburgh (1990) - only felids.
Tiger - 342 mm. = 316.8 kg (Est.) ---- 260 kg (Real)
Lion - 355 mm. = 355.8 kg (Est.) ---- 250 kg (Real)
Jaguar - 280 mm. = 170.1 kg (Est.) ---- 148 kg (Real)
Leopard - 256 mm. = 128.7 kg (Est.) ---- 96 kg (Real)
Snow leopard - 174 mm. = 38.7 kg (Est.) ---- 52 kg (Real)
Now we can see why thise formula is not reliable, not with Panthera cats at least.
(06-01-2022, 10:15 AM)LonePredator Wrote: If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Actually it will be a gross overestimation, and here is an example, using the biggest CBL from the Panthera cats, taken by scientists, here you can see the weights calculated (in red) and at the right the maximum weights actually recorded (in blue):
Formula use: log mass = 3.11 * log CBL - 5.38 - Van Valkeburgh (1990) - only felids.
Tiger - 342 mm. = 316.8 kg (Est.) ---- 260 kg (Real)
Lion - 355 mm. = 355.8 kg (Est.) ---- 250 kg (Real)
Jaguar - 280 mm. = 170.1 kg (Est.) ---- 148 kg (Real)
Leopard - 256 mm. = 128.7 kg (Est.) ---- 96 kg (Real)
Snow leopard - 174 mm. = 38.7 kg (Est.) ---- 52 kg (Real)
Now we can see why thise formula is not reliable, not with Panthera cats at least.
Yeah yeah sorry that’s right. A relatively bigger head would mean an overestimation, my bad.
(06-01-2022, 10:15 AM)LonePredator Wrote: If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Actually it will be a gross overestimation, and here is an example, using the biggest CBL from the Panthera cats, taken by scientists, here you can see the weights calculated (in red) and at the right the maximum weights actually recorded (in blue):
Formula use: log mass = 3.11 * log CBL - 5.38 - Van Valkeburgh (1990) - only felids.
Tiger - 342 mm. = 316.8 kg (Est.) ---- 260 kg (Real)
Lion - 355 mm. = 355.8 kg (Est.) ---- 250 kg (Real)
Jaguar - 280 mm. = 170.1 kg (Est.) ---- 148 kg (Real)
Leopard - 256 mm. = 128.7 kg (Est.) ---- 96 kg (Real)
Snow leopard - 174 mm. = 38.7 kg (Est.) ---- 52 kg (Real)
Now we can see why thise formula is not reliable, not with Panthera cats at least.
would using the van vaulkenburg formula on populator skulls create huge overestimations as well, also i think a way to get an exact weight for the biggest populators is to scale it up from the skull of bonaerensis 46, as the entire skeleton of bonaernesis 46 managed to get completely preserved, although its just my opinion and i dont really know to much so idk
06-02-2022, 07:54 AM( This post was last modified: 06-02-2022, 07:55 AM by LonePredator )
(06-02-2022, 06:56 AM)jrocks Wrote:
(06-01-2022, 08:46 PM)GuateGojira Wrote:
(06-01-2022, 10:15 AM)LonePredator Wrote: If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Actually it will be a gross overestimation, and here is an example, using the biggest CBL from the Panthera cats, taken by scientists, here you can see the weights calculated (in red) and at the right the maximum weights actually recorded (in blue):
Formula use: log mass = 3.11 * log CBL - 5.38 - Van Valkeburgh (1990) - only felids.
Tiger - 342 mm. = 316.8 kg (Est.) ---- 260 kg (Real)
Lion - 355 mm. = 355.8 kg (Est.) ---- 250 kg (Real)
Jaguar - 280 mm. = 170.1 kg (Est.) ---- 148 kg (Real)
Leopard - 256 mm. = 128.7 kg (Est.) ---- 96 kg (Real)
Snow leopard - 174 mm. = 38.7 kg (Est.) ---- 52 kg (Real)
Now we can see why thise formula is not reliable, not with Panthera cats at least.
would using the van vaulkenburg formula on populator skulls create huge overestimations as well, also i think a way to get an exact weight for the biggest populators is to scale it up from the skull of bonaerensis 46, as the entire skeleton of bonaernesis 46 managed to get completely preserved, although its just my opinion and i dont really know to much so idk
That would still not be a good way to estimate because of the same reasons as I described previously.
And yes, a big overestimation is possible but how big or small can’t be said with absolute certainty. Let’s just say it was somewhere between 350-400kg rather than 436kg since apparently some felids with relatively even smaller skulls were used to make this equation.
(06-01-2022, 10:15 AM)LonePredator Wrote: If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Actually it will be a gross overestimation, and here is an example, using the biggest CBL from the Panthera cats, taken by scientists, here you can see the weights calculated (in red) and at the right the maximum weights actually recorded (in blue):
Formula use: log mass = 3.11 * log CBL - 5.38 - Van Valkeburgh (1990) - only felids.
Tiger - 342 mm. = 316.8 kg (Est.) ---- 260 kg (Real)
Lion - 355 mm. = 355.8 kg (Est.) ---- 250 kg (Real)
Jaguar - 280 mm. = 170.1 kg (Est.) ---- 148 kg (Real)
Leopard - 256 mm. = 128.7 kg (Est.) ---- 96 kg (Real)
Snow leopard - 174 mm. = 38.7 kg (Est.) ---- 52 kg (Real)
Now we can see why thise formula is not reliable, not with Panthera cats at least.
would using the van vaulkenburg formula on populator skulls create huge overestimations as well, also i think a way to get an exact weight for the biggest populators is to scale it up from the skull of bonaerensis 46, as the entire skeleton of bonaernesis 46 managed to get completely preserved, although its just my opinion and i dont really know to much so idk
That would still not be a good way to estimate because of the same reasons as I described previously.
And yes, a big overestimation is possible but how big or small can’t be said with absolute certainty. Let’s just say it was somewhere between 350-400kg rather than 436kg since apparently some felids with relatively even smaller skulls were used to make this equation.
i feel like it would be best if smilodon bonaerensis 46 was between 350-400 kg, the reason i think that is because the largest populator specimen christiansen and harris estimated was 360 kg, and smilodon bonaerensis 46 was even bigger than that 360 kg specimen christiansen and harris estimated in 2005. christiansen and harris also said that there were large specimens of populator that exceeded 400 kg, and they said that in their study in 2005. 2005 is before the 15.4 inch uruguay skull and the 16.07 inch skull were taken into account, both skulls of which are now considered the 2 largest specimens of populator and both of those skull specimens are much larger than bonaerensis 46
06-02-2022, 08:40 AM( This post was last modified: 06-02-2022, 06:10 PM by LonePredator )
(06-02-2022, 08:12 AM)jrocks Wrote:
(06-02-2022, 07:54 AM)LonePredator Wrote:
(06-02-2022, 06:56 AM)jrocks Wrote:
(06-01-2022, 08:46 PM)GuateGojira Wrote:
(06-01-2022, 10:15 AM)LonePredator Wrote: If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Actually it will be a gross overestimation, and here is an example, using the biggest CBL from the Panthera cats, taken by scientists, here you can see the weights calculated (in red) and at the right the maximum weights actually recorded (in blue):
Formula use: log mass = 3.11 * log CBL - 5.38 - Van Valkeburgh (1990) - only felids.
Tiger - 342 mm. = 316.8 kg (Est.) ---- 260 kg (Real)
Lion - 355 mm. = 355.8 kg (Est.) ---- 250 kg (Real)
Jaguar - 280 mm. = 170.1 kg (Est.) ---- 148 kg (Real)
Leopard - 256 mm. = 128.7 kg (Est.) ---- 96 kg (Real)
Snow leopard - 174 mm. = 38.7 kg (Est.) ---- 52 kg (Real)
Now we can see why thise formula is not reliable, not with Panthera cats at least.
would using the van vaulkenburg formula on populator skulls create huge overestimations as well, also i think a way to get an exact weight for the biggest populators is to scale it up from the skull of bonaerensis 46, as the entire skeleton of bonaernesis 46 managed to get completely preserved, although its just my opinion and i dont really know to much so idk
That would still not be a good way to estimate because of the same reasons as I described previously.
And yes, a big overestimation is possible but how big or small can’t be said with absolute certainty. Let’s just say it was somewhere between 350-400kg rather than 436kg since apparently some felids with relatively even smaller skulls were used to make this equation.
i feel like it would be best if smilodon bonaerensis 46 was between 350-400 kg, the reason i think that is because the largest populator specimen christiansen and harris estimated was 360 kg, and smilodon bonaerensis 46 was even bigger than that 360 kg specimen christiansen and harris estimated in 2005. christiansen and harris also said that there were large specimens of populator that exceeded 400 kg, and they said that in their study in 2005. 2005 is before the 15.4 inch uruguay skull and the 16.07 inch skull were taken into account, both skulls of which are now considered the 2 largest specimens of populator and both of those skull specimens are much larger than bonaerensis 46
I don’t know the exact measurements of the specimens you are mentioning. Do you have all the bone measurements of all these specimens? And also the measurements of the 360kg specimen estimated by Christiansen and Harris?
Maybe if we have the measurements then we might be able to make a better comparison and get a rough idea of their weights.
But once again, we can’t say from minor skull variations that the whole specimen was bigger. The difference in skull size is not that much after all and isometry usually only works correcty when there is a good enough size difference between the skulls.
(06-01-2022, 10:15 AM)LonePredator Wrote: If you use the Van Valkenburgh formula to estimate Lions then the weight will be a huge underestimation, if you estimate Tiger, it will still be a big underestimation and if you estimate Smilodon Populator then it will be a big overestimation.
Actually it will be a gross overestimation, and here is an example, using the biggest CBL from the Panthera cats, taken by scientists, here you can see the weights calculated (in red) and at the right the maximum weights actually recorded (in blue):
Formula use: log mass = 3.11 * log CBL - 5.38 - Van Valkeburgh (1990) - only felids.
Tiger - 342 mm. = 316.8 kg (Est.) ---- 260 kg (Real)
Lion - 355 mm. = 355.8 kg (Est.) ---- 250 kg (Real)
Jaguar - 280 mm. = 170.1 kg (Est.) ---- 148 kg (Real)
Leopard - 256 mm. = 128.7 kg (Est.) ---- 96 kg (Real)
Snow leopard - 174 mm. = 38.7 kg (Est.) ---- 52 kg (Real)
Now we can see why thise formula is not reliable, not with Panthera cats at least.
would using the van vaulkenburg formula on populator skulls create huge overestimations as well, also i think a way to get an exact weight for the biggest populators is to scale it up from the skull of bonaerensis 46, as the entire skeleton of bonaernesis 46 managed to get completely preserved, although its just my opinion and i dont really know to much so idk
That would still not be a good way to estimate because of the same reasons as I described previously.
And yes, a big overestimation is possible but how big or small can’t be said with absolute certainty. Let’s just say it was somewhere between 350-400kg rather than 436kg since apparently some felids with relatively even smaller skulls were used to make this equation.
i feel like it would be best if smilodon bonaerensis 46 was between 350-400 kg, the reason i think that is because the largest populator specimen christiansen and harris estimated was 360 kg, and smilodon bonaerensis 46 was even bigger than that 360 kg specimen christiansen and harris estimated in 2005. christiansen and harris also said that there were large specimens of populator that exceeded 400 kg, and they said that in their study in 2005. 2005 is before the 15.4 inch uruguay skull and the 16.07 inch skull were taken into account, both skulls of which are now considered the 2 largest specimens of populator and both of those skull specimens are much larger than bonaerensis 46
I don’t know the exact measurements of the specimens you are mentioning. Do you have all the bone measurements of all these specimens? And also the measurements of the 360kg specimen estimated by Christiansen and Harris?
Maybe if we have the measurements then we might be able to make a better comparison and get a rough idea of their weights.
But once again, we can’t say from minor skull variations that the whole specimen was bigger. The difference in skull size is not that much after all.
this is a sherani study from 2016, it says on the 15th page that christiansen and harris estimated that the largest of the same specimen did not exceed 360 kg, and because of that i think the specimen that sherani puts as 450 kg is the one that christiansen and harris put as 360 kg, although i dont know for sure if that same largest specimen was the one chrisitansen estimated at 360 kg as i cant get access that full christiansen paper. what i do know for sure is the specimen christiansen and harris estimated to be at 360 kg is smaller than smilodon bonaeresis 46, and tigerluver said that himself, you should ask tigerluver or guate to make sure the 374.5 mm humerus is the specimen christiansen estimated at 360 kg, below here is a link for i think the entire skeletal measurements of bonaerensis 46
