Smilodon populator

[LonePredator]

(05-30-2022, 09:26 PM)GuateGojira Wrote:

(05-28-2022, 06:26 AM)LonePredator Wrote: 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?

As @jrocks said, those are two different skulls.

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. Reply