Freak Felids - A Discussion of History's Largest Felines

[GuateGojira]

(01-16-2022, 10:07 AM)tigerluver Wrote: Mandible length of fragment is affected by allometry. The "mandible length" measurement in the tiger paper is not the same as complete mandible length. Rather, you will see that as the mandible size increased, the surrogate "mandible length" comprises proportionately less and less of the total mandible. In other words, positive allometry. Here is a visual:

*This image is copyright of its original author

*This image is copyright of its original author
The larger specimens have a shorter horizontal ramus and surrogate mandible length compared to total mandible length. You will see here that comparison of the surrogate "mandible length" between 1a and 3a will underestimate 3a by a massive 17% (65/76). Therefore, the clean isometric relation of total mandible length does not apply. This is why height and width dimensions of the ramus are important, as there is less allometric effect on estimation theoretically when we pool together many measurements. This is also probably why multiple measurements are used in the estimate, to make up for this error. It is important to know these allometric relationships before choosing a single measurement as "most accurate" as clearly, the surrogate mandible length has hefty underestimation.

The comparative specimen used to estimate via mandible length is very small. As such, using a scale factor of 3 would underestimate the mass as the actual scale factor is greater than 3.

It may happen in time that the Christiansen estimations show to be underestimates across the board. The database is measured from digital photos, which can result in measurements a bit exaggerated as compared to in person measurements. This underestimates any specimen not also measured digitally.

Just for fun, nothing official, I tried to make an estimation of size for the Borneo Pleistocene giant tiger, using the fragment of the mandible in the document of Sherani (2019). I found that when I used the mandible of the Ngandong tiger NM2671 it matched were well so I tried to use it as a surrogate. However what I corroborated (as Tigerluver already explained it, and I quote his post here) is that the recostruction is very subjective and depends of the mandible and the skull that you use (mainland or sunda, male or female, adult or young, etc.). Just to give you an idea, the reconstructions that I made give me a range of skull length between 450 - 500 mm+, which implies a head-body of 240 - 270 cm. I am impresed about how variable can be a reconstruction in this form, specially when the fossil is so fragmentary. I remember that Tigerluver told me that the skull of this tiger could be about 480 mm in GL and a head-body of about 260 cm, so my results were not too far from his calculations.

It will be interesting if some one in the future could make a comparison of this mandible with other modern tigers, using real measurements from the bones and not just images in Photoshop (like I have done in this moment) in order to provide a more reliable calculation for the size of this giant tiger. For the moment, I stay with the estimation of Tigerluver. Reply