(11-12-2022, 06:29 PM)LonePredator Wrote:

*This image is copyright of its original author

This is what I imagine Smilodon Populator (right) and Fatalis (left) would have looked like (with slightly more loose skin and slightly higher bodyfat as well as thick fur for Fatalis). Although they would be bulkier and more muscular than modern Bengal and Amur Tigers.

And although it is believed that Smilodons may have looked as bulky and ‘thick’ as Brown Bears, I partially disagree with this because:

• The main reason for Brown Bears having very robust bones is the extra mass from body fat while Smilodons had muscle and since muscle is denser than fat, it would have lower volume per unit mass while fat would have higher volume and thus appear ‘thicker’.
• Muscle is motile while fat is immotile, the motile property of muscle would allow it to resist and ease up some of the stress on the limb bones while fat would exert a lot more stress on the mass on the limb bones (which would require thicker bones)
  

So mainly, extra fat mass would need thicker limb bones compared to muscle mass for the limb bones to withstand the weight of extra fat mass.

Quote:

*This image is copyright of its original author

*This image is copyright of its original author


This is what I imagine Smilodon Populator (right) and Fatalis (left) would have looked like (with slightly more loose skin and slightly higher bodyfat as well as thick fur for Fatalis). Although they would be bulkier and more muscular than modern Bengal and Amur Tigers.

And although it is believed that Smilodons may have looked as bulky and ‘thick’ as Brown Bears, I partially disagree with this because:

• The main reason for Brown Bears having very robust bones is the extra mass from body fat while Smilodons had muscle and since muscle is denser than fat, it would have lower volume per unit mass while fat would have higher volume and thus appear ‘thicker’.
• Muscle is motile while fat is immotile, the motile property of muscle would allow it to resist and ease up some of the stress on the limb bones while fat would exert a lot more stress on the mass on the limb bones (which would require thicker bones)
  
  
  

So mainly, extra fat mass would need thicker limb bones compared to muscle mass for the limb bones to withstand the weight of extra fat mass.

(11-17-2022, 12:30 AM)Matias Wrote: I would add: prey selectively chosen throughout its local evolutionary history, more consistent with its effective capacity for predation and dietary use, not necessarily aimed at the largest animals of the time, such as mastodons (and other members of the genus) and giant sloths. Best suited to bison, camels, moose...

The biomass of herbivores and carnivores is highest in North America. The massive size of the Smilodon Populator tells us that finding consistent answers is a future challenge to build on. After all, mysteries are effective in destroying predictable reasoning.

(11-17-2022, 12:30 AM)Matias Wrote:

Quote:

*This image is copyright of its original author

*This image is copyright of its original author


This is what I imagine Smilodon Populator (right) and Fatalis (left) would have looked like (with slightly more loose skin and slightly higher bodyfat as well as thick fur for Fatalis). Although they would be bulkier and more muscular than modern Bengal and Amur Tigers.

And although it is believed that Smilodons may have looked as bulky and ‘thick’ as Brown Bears, I partially disagree with this because:

• The main reason for Brown Bears having very robust bones is the extra mass from body fat while Smilodons had muscle and since muscle is denser than fat, it would have lower volume per unit mass while fat would have higher volume and thus appear ‘thicker’.
• Muscle is motile while fat is immotile, the motile property of muscle would allow it to resist and ease up some of the stress on the limb bones while fat would exert a lot more stress on the mass on the limb bones (which would require thicker bones)
  
  
  

So mainly, extra fat mass would need thicker limb bones compared to muscle mass for the limb bones to withstand the weight of extra fat mass.

“As the muscles pull on the bones, the bones respond by getting stronger. Since saber-toothed had thicker arm bones, we think they must have used their forelimbs more than other cats. The thicker cortical bone seen makes sense if the arms are under greater stress than is normally expected for felines of their size. Just as lifting weights improves bone density over time, the repeated effort of grappling with prey may also have resulted in thicker and stronger arm bones. As the muscles pull on the bones, the bones respond by getting stronger; that's where the powerful arms come in - these predators may have immobilized victims with their heavily muscled forelimbs to protect their teeth from fractures as they bit into struggling prey, Meachen-Samuels said.

I would add: prey selectively chosen throughout its local evolutionary history, more consistent with its effective capacity for predation and dietary use, not necessarily aimed at the largest animals of the time, such as mastodons (and other members of the genus) and giant sloths. Best suited to bison, camels, moose...

The biomass of herbivores and carnivores is highest in North America. The massive size of the Smilodon Populator tells us that finding consistent answers is a future challenge to build on. After all, mysteries are effective in destroying predictable reasoning.

In South America we had the largest known bear (Arctotherium), as well as huge specimens of the genus Arctodus also roamed around here. The ecology of felines, as far as is known, does not serve as a mirror on the life dynamics of bears and vice versa (whatever the species). Focus on bones and their biomechanical components and the whole ontogenetic and filogenetic process.

Your observations were interesting!

(11-23-2022, 10:33 AM)AndresVida Wrote:

(11-17-2022, 12:30 AM)Matias Wrote: I would add: prey selectively chosen throughout its local evolutionary history, more consistent with its effective capacity for predation and dietary use, not necessarily aimed at the largest animals of the time, such as mastodons (and other members of the genus) and giant sloths. Best suited to bison, camels, moose...

The biomass of herbivores and carnivores is highest in North America. The massive size of the Smilodon Populator tells us that finding consistent answers is a future challenge to build on. After all, mysteries are effective in destroying predictable reasoning.

Well what would we expect from a 420 - 430+ behemoth, that cat is on another league

(11-17-2022, 12:30 AM)Matias Wrote:

Quote:

*This image is copyright of its original author

*This image is copyright of its original author


This is what I imagine Smilodon Populator (right) and Fatalis (left) would have looked like (with slightly more loose skin and slightly higher bodyfat as well as thick fur for Fatalis). Although they would be bulkier and more muscular than modern Bengal and Amur Tigers.

And although it is believed that Smilodons may have looked as bulky and ‘thick’ as Brown Bears, I partially disagree with this because:

• The main reason for Brown Bears having very robust bones is the extra mass from body fat while Smilodons had muscle and since muscle is denser than fat, it would have lower volume per unit mass while fat would have higher volume and thus appear ‘thicker’.
• Muscle is motile while fat is immotile, the motile property of muscle would allow it to resist and ease up some of the stress on the limb bones while fat would exert a lot more stress on the mass on the limb bones (which would require thicker bones)
  
  
  

So mainly, extra fat mass would need thicker limb bones compared to muscle mass for the limb bones to withstand the weight of extra fat mass.

“As the muscles pull on the bones, the bones respond by getting stronger. Since saber-toothed had thicker arm bones, we think they must have used their forelimbs more than other cats. The thicker cortical bone seen makes sense if the arms are under greater stress than is normally expected for felines of their size. Just as lifting weights improves bone density over time, the repeated effort of grappling with prey may also have resulted in thicker and stronger arm bones. As the muscles pull on the bones, the bones respond by getting stronger; that's where the powerful arms come in - these predators may have immobilized victims with their heavily muscled forelimbs to protect their teeth from fractures as they bit into struggling prey, Meachen-Samuels said.

I would add: prey selectively chosen throughout its local evolutionary history, more consistent with its effective capacity for predation and dietary use, not necessarily aimed at the largest animals of the time, such as mastodons (and other members of the genus) and giant sloths. Best suited to bison, camels, moose...

The biomass of herbivores and carnivores is highest in North America. The massive size of the Smilodon Populator tells us that finding consistent answers is a future challenge to build on. After all, mysteries are effective in destroying predictable reasoning.

In South America we had the largest known bear (Arctotherium), as well as huge specimens of the genus Arctodus also roamed around here. The ecology of felines, as far as is known, does not serve as a mirror on the life dynamics of bears and vice versa (whatever the species). Focus on bones and their biomechanical components and the whole ontogenetic and filogenetic process.

Your observations were interesting!