Smilodon populator

[LonePredator]

(05-18-2022, 02:03 AM)GuateGojira Wrote:

(05-17-2022, 10:01 PM)LonePredator Wrote: Yes, the 517kg weight must be treated with extreme caution because estimating the weight of Smilodon Populator is no easy task, we have no living animal which has the same or similar proportions as Smilodon Populators unlike in the case of prehistoric Lions and Tigers which are much more easier to estimate as animals with similar or almost same proportions as them still exist.

Now for this reason, the method used would make or break the whole estimation. And since the method of Christiansen and Harris (2005) is considered the most reliable, we could have used their 358.4kg specimen as surrogate to make a rough isometric estimation for these specimens but the problem is that the 358.4kg specimen was based on the humerus so isometric scaling can only be done on another humerus.

Unfortunately we only have skulls on our hands and it would not be possible to estimate their weight unless we get our hands on the original method of Christiansen and Harris and see how it works and how it could apply in this case if it really can.

I will like to read the study of Prevosti & Martin (2013) just to see what methods they used, because since I see "Anyonge" mentioned there, it smells at "exageration". But you are right, there is no modern animal with the same morphology, as Smilodon genus is like a cat that wanted to be a bear!


The issue with Christiansen & Harris (2005) is that they use a multifactorial aproach, as they apply several measurements in the same bone to get a "weighted" average. So, in order to apply this set of formulas to a new specimen, we will need to have a good set of measurements, if not, a single formula produce incorrect data. Check that in the set of measurements the "Total length" alone produce a very low value, so is not recomended to use a single measurement, with them at least.

Other issue, remember that we are using a single bone, but when a series of bones from the same specimen are used, the range of estimated weights is very large. For example the specimen CN52 has humerus/ulna/femur/tibia asociated, but check the average body mass "weighted", of the set of measurements, of each bone:

Humerus: 316.2 kg
Ulna: 231.2 kg
Femur: 246.8 kg
Tibia: 238.5 kg

As we can see, there is a big variation between the body masses of each bone, and also add the fact that the morphology is different so that may explain why the legs provide lower weights. The average of the 4 bone is 258.2 kg, so in theory that is the body mass taking in count all the bones, but as I said, the small size of the legs may affect this estimation.

Yes, I totally agree, any study that is based on or inspired by the Anyonge one needs to be looked at with skepticism.

And yes I just saw a glimpse of their method and I’ll read more of it later but I did not mean to say that I’ll redo the whole thing they did on this case, I meant to say that as they made different measurements of multiple parts of the same bone and then they calculated the weight possible for the specimen which that bone belonged to.

So what I meant to say is that as Christiansen and Harris had already estimated the possible weight for the specimen with a humerus of particular length has already been done (and they have already fixed the disparities by measuring different parts of the same bone)

So now I meant that as they have already estimated the weight of a Smilodon Populator which has a humerus of 390mm so now we can get a rough idea how much the Populator of 405mm will weight through isometry as all the other calculations have already been done.

And yes, this is a huge issue, especially the femur of the Populator would be very likely to produce an underestimation when estimated from extant specimens.

But overall I like the method of Christiansen and Harris, they calculated all the variations in the bone of Populator compared to a specimen from living species. Their calculation of different measurements of the same bone is arguably the best way to tell how much weight the current bone would produce with all those different variations in that same bone. Reply