American Lion (Panthera atrox)

[GuateGojira]

(04-27-2017, 09:46 PM)epaiva Wrote: Size of Largest Panthera atrox skeleton in Rancho La Brea:

Mr H. Todd Wheeler send me information of largest Panthera atrox skeleton exhibited in Rancho La Brea, 
the information is: 
The largest P atrox from rancho La Brea was up to around 2 meters in head and body with shoulder height up to 1,2 meters.

My question to the experts here in the Forum:
What would be the estimated size and weight for this P atrox when it was alive?

@tigerluver  @peter   @GrizzlyClaws   @GuateGojira 

Hello again @epaiva, nice to see you here again.

Well, based in many documents, the maximum size that I have saw, for the largest Panthera atrox specimen seems to be 250 cm in head-body length. However, none of the sources that I have read mention if this estimation is calculated for an animal measured "between pegs - straight line" or "along the curves - pressing the tape".

With a skull of about 467.5 mm, it is very easy to see that a head-body of 250 cm seems very plausible. Some years ago I made a table (never published) with head-body lengths and skulls of African lions, in order to estimate the ratio skull - head-body, but sadly I lost that document. I am going to try to do it again.

However, now that you have published a picture of the large Amur tiger skull of 393 mm together with the huge skull of Panthera atrox of c.470 mm, I could see that the difference, although very evident, is not as dramatic as we can expected. And taking in count that a tiger with a skull of this size may measure between 210-220 cm, the size of Panthera atrox, following the tiger proportions, could measure between 240-250 cm in straight line. In this case, as the lion have a relative larger head in relation with its body, the head-body length of Panthera atrox, following the lion proportions, should be shorter at about 230-240 cm, but for the moment this is just a guess.

On the weight issue, there are many estimations, somewhat very exaggerated, like for example the results of Anyonge (1993). Wheeler and Jefferson (2009) used the equations of Christiansen & Harris (2005), but only the one of the greatest length and the midshaft wide (not weighted) and the results are very contradictory. The widest femur produced a figure of 478 kg, which is an absurd exaggeration, while the longest femur produced a figure of only 271 kg, which is a great underestimation. The problem is that single bones produced different estimations, and this is clear wen we see the result of the complete (associated bones) of Smilodon fatalis and Smilodon populator fossils used by Christiansen & Harris (2005):

* Smilodon fatalis - LACM PMS1-1:
Range: 195.1 - 279.0 kg, mean of 4 bones= 241 kg (weighted).

* Smilodon populator  - CN52
Range: 231.2 - 316.2 kg, mean of 4 bones= 258.2 kg (weighted).

Using a single fossil, we produce single estimations, sadly this is the norm as is very rare to found full skeletons or at least, several associated long bones. So the figures of Wheeler and Jefferson do not represent the full set of measurements and formulas used by Christiansen & Harris (2005). Interestingly, the average of all them figures produce a weight of 251 kg for males and a maximum of 332 kg, which is slightly smaller than than the figures of Christiansen & Harris (2009; using the equation of Sorkin of the allometric comparison) and those using the formulas of Legendre & Roth (1988), which from my point of view is more accurate than the dental formulas of Van Valkenburg (1990). This is the comparison overall (males only):

     Values in Kilograms            Mean        Max         Min
Legendre & Roth (1988):            266.2       343.0      223.2
Wheeler and Jefferson (2009):    251.0       332.0      218.0
Christiansen & Harris (2009):       255.6       351.0      199.0

Based in these figures, the maximum weight for the largest Panthera atrox specimen in this studies seems to be between 330 - 350 kg, which seems reasonable taking in count that the largest lions and tigers reach figures of about 280 - 290 kg (excluding stomach content). However lets take in count that the maximum weight came from the second largest skull, so is possible to estimate that the weight for the largest Panthera atrox skull (Univ. Calif. 14001) was of about 360 kg.

The maximum shoulder height that I have saw was reported by Turner & Anton and is of 125 cm. The tail length could be of 1 meter, at least, so using this information, I think that is safe to estimate the maximum size of Panthera atrox like this:

* Head-body length: 240 - 250 cm
* Shoulder height: 125 cm.
* Weight: 350 - 360 kg.

If this Panthera atrox skeleton represent the size produced by the largest bones recorded, in theory it should present this size.

Just my two cents. Greetings. Reply