Comparing grappling ability of extant Ursids

[Verdugo]

(08-15-2024, 07:58 AM)peter Wrote: Nice. Also like the sources (reliable). 

Anything known about the difference between bones of Pleistocene big cats and those of today? And what about today's bears and big cats? In what respects do they compare and in what respects are the differences most outspoken? Most likely reasons?

Hi Peter, glad you enjoy my post.

I was not going comment anything about this comparison cause I made it quite some times ago and posted on a different forum. I posted it on WF primarily to backup it case it will be deleted on the other forum cause it did take me some efforts to make this, and also hopefully some folks at WF would appreciate it.

However, if you want my inputs... I can't comment too much on Pleistocene Big Cats cause I have not been researching on them for quite some times. I guess one thing that is quite apparent in this comparison is the robusticity of Pleistocene Big Cats, especially the Cave lion, in comparison to extant Pantherine such as Siberian tiger. The humerus's diaphysis of Cave lion is markedly more robust than that of extant Pantherine, being more or less comparable to those of large bears such Polar bear or Alaskan brown bear. Higher robusticity means that the bone has a higher safety factor and thus less prone to structural failures when under loads. Robusticity is a function of size, larger animals simply have relatively more robust bones to help them compensate for exponentially increase in mass due to square cube law. However, the humerus of Machairodus lahayishupup, while being more robust than that of extant Pantherine, is still less robust than Cave lion, even though Machairodus is a very large cat itself. Thus, I reckon the increase robusticity in the Cave lion is probably also related to the need of withstanding the stresses from grappling with larger prehistoric preys.

With regards to Bears and extant Pantherines comparison, the humerus of Bears are markedly more robust than that of Pantherines, both at the diaphysis and especially at the distal epiphysis. Since robusticity is a function of size, and the bears in the comparison (Polar bear and Alaskan brown bear) are so much larger than the Pantherine (Siberian tiger), the greater robusticity of the diaphysis is expected. The wider distal epiphysis is probably to due to the fact that Bears generally have wider articular area which allows them to have more range of motion at the elbow such as pronation and supination. One thing that also stands out is the relatively longer and more pronounced (and rugose) deltopectoral crest in Bears in comparison to Pantherines. This suggests more distal attachments of muscles attached to crest such as deltoid, pectorales, cleidobrachialis, and thus higher mechanical advantage for force productions, at the cost of speed. While in Pantherines, the crest is moderate in length, suggests a balance system of both speed and force. Another thing that also stands out is the more developed lateral supinator ridge in Bears when compared to Pantherines. The ridge provides origins area for muscles related to flexing the elbow and supinate antebrachium. So I reckon these functions should be quite strong in Bears.

Also, I'm trying to be brief, of course there are a lot more to unpack with regards to anatomical comparison between Bears and Big Cats. However, I'm planning to post more Bears vs Bears comparison rather than Bears vs Big Cats cause there are already a lot of those on the Internet. Perhaps, I could make dedicated posts to compare Bears and Big Cats anatomy at some points if I'm feeling motivated, but probably not in near future. Reply