Xenosmilus hodsonae

[GuateGojira]

(02-13-2017, 07:54 AM)tigerluver Wrote: Body mass of Xenosmilus hodsonae
With four long bones, we have many different estimators. As Xenosmilus is not a giant as in the likes of the more popular Pleistocene felids, equations can be used but are far from needed.

The humerus is tiger-lion sized in length, thus a mass of 200-240 kg can be applied for this measurement alone. The articular length falls in the same tiger-lion mass range. The midshaft diameter is greater proportionately than that of lion and tiger humeri if you consider the Christiansen and Harris (2005) diameters are from the midshaft as well. Based on Christansen's (1999) assertion that the least tranverse diameter of the humeral shaft is "usually located at midshaft in humerus and femur but often more proximally and distally situated in the radius and tibia, respectively," it is probably okay to. I personally feel the least traverse diameter falls a bit south the midshaft. Nonetheless, Christiansen's data is probably midshaft and thus the midshaft would provide a mass range of 240-290 kg. All in all, the humerus indicates a specimen with a mass of ~235 kg assuming built in between the lion and the tiger, and some thing closer to 270 kg assuming a more tiger-like built. 

The femur is short. The length based mass would on its own be around 170 kg. However, referring to the figure above about forelimb and hindlimb ratios, we see X. hodsonae had a very posteriorly sloped body mapping, thus estimating mass via femur length of a cat would be inaccurate. The femoral distal width is large for both a tiger and lion, but not exceptional. Thus a mass of 200-290 kg (yes, that's a large range but the two largest cats of today are proportioned quite differently in this regard) could apply for this measurement. The femoral midshaft diameter produces a lesser mass of 200-240 kg. Overall, if we ignore the length measurement, a mass of ~230 kg assuming built in between the lion and the tiger, and some thing closer to 270 kg assuming a more tiger-like built.

This is what I remembered. So like I said, there is no way that Xenosmilus weighed more than Smilodon fatalis, at least not with the specimens that we have. I remember that the largest skull known (until now....) was less than than 350 mm in GL, from this image we can see that the CBL is less than 290 mm:

*This image is copyright of its original author

Here is a reconstruction of the skull:

*This image is copyright of its original author

However, take in count that proportionally speaking, the head was relative small in comparison to the body, according with L. D. Martin and his team.

Here are some reconstructions from the book about this animal, sadly I still don't have the full one.

*This image is copyright of its original author

*This image is copyright of its original author

So, it seems that this cat was about the same weight as modern tigers and lions, but surpassed by S. fatalis. Reply