Indarctos Size

[brobear]

app.pan.pl/archive/published/app49/app49-325.pdf

First posted by Grraahh.

Indarctos spp. were the first large-bodied bears with omnivorous tendencies. Two Indarctos fossils assigned to I. arctoides ssp. by Bernor, Feibel, et al. (2003) and Viranta and Werdelin (2003) show that the genus had a wide geographic range in Europe in the Middle Miocene and was represented by at least two contemporaneous species. Present work shows that the two species of Indarctos lived in a mixture of environments, and were not clearly separated into distinct habitats. Indarctos seems to have evolved during an interval of faunal turnover in Europe. The appearance of Indarctos coincided with an extinction of small omnivorous mammals and was accompanied by the appearance of other large omnivores.

Viranta, Suvi. Habitat preferences of European Middle Miocene omnivorous ursids. Acta Palaeontologica Polonica 49 (2), 2004: 325-327.

"For example, using a regression for modern Ursidae, the estimated body size for the extinct bear Indarctos atticus was in excess of 3000 kg. Although I.atticus is certainly one of the largest terrestrial carnivorans to have ever existed, a body mass in excess of three metric tons is highly improbable."

Legendre, Serge & Roth, Claudia (1988), "Correlation of carnassial tooth size and body weight in recent carnivores (Mammalia)", Historical Biology 1 (1): 85–98. 
 
3000 kg = 6,600+ pounds. 

[brobear]

A SyFy drawing of Indarctos vs Allosaurus.
 

[brobear]

Go to: wildfact.com/forum/ and then to: Bears of the Pleistocene - post #202 by HyperNova.
Knowledge slays the "monster bear."
115 cm ( 3 feet 9 inches ) - 123 cm ( 4 feet ).

[brobear]

As can be seen in the above post, the biggest of the Indarctos species were the size of modern-day inland grizzlies. As HyperNova points out, all too often, when a new prehistoric animal is discovered, the size of the animal is greatly exaggerated. Examples: Arctotherium angustidens was first estimated at nearly 2 tons (1800kg). Now, we estimate him at roughly 1100 kg (2400 pounds). The tyrant sea bear was first estimated at a weight of 2500 pounds (1134 kg). Now we know that he weighed roughly 850 kg (1875 pounds). 
However, Indarctos atticus was so overwhelmingly over-exaggerated to the point of ridiculousness! He was estimated to have weighed from 6,000 pounds (2700 kg) to 8000 pounds (3600 kg). In reality, he would have weighed from 500 to 700 pounds (227 to 318 kg). 

[brobear]

245 kg = 540 pounds.
                                             

[Deleted]

Hum, the size of this bear is not clear. I don't think there is a scientific study about his mass, only guys who make drawings and claim anything  . It seems that this bear can get really big!

Here is a paper about Indarctos punjabiensis atticus : kmkjournals.com/upload/PDF/RJT/1/ther1_2_083_089_Baryshnikov.pdf. It is not about mass but at the end we have a citation stipulating a mass of 500kg. But this estimation is old (1997).

Some years ago a guy on another forum talked about an enormous lower jaw about Indarctos in Oregon. I think i have seen the photo, unfortunately i can't recover it. In fact this lower jaw was so big that the guy who provided the image was thinking that this specimen could have reached a mass similar to the largest cave bears, so 1000kg!

A modern study about Indarctos and Amphimachairodus: link.springer.com/article/10.1007/s10914-021-09546-9. We have some images and the humerus is large(first image):

media.springernature.com/lw685/springer-static/image/art:10.1007%2Fs10914-021-09546-9/MediaObjects/10914_2021_9546_Fig6_HTML.jpg

media.springernature.com/lw685/springer-static/image/art:10.1007%2Fs10914-021-09546-9/MediaObjects/10914_2021_9546_Fig14_HTML.jpg

media.springernature.com/lw685/springer-static/image/art:10.1007%2Fs10914-021-09546-9/MediaObjects/10914_2021_9546_Fig3_HTML.jpg

And these bones are big, what do you think?

[Deleted]

The humerus here is 50,6 cm in length. To my knowledge it is larger than any Ursus spelaeus humerus i know. And the humerus is robust, so this bear is massive.
It seems to me that the huge mandible comes from another specimen but i must read the paper in detail to be sure.

The humerus of the big specimen Ursus ingressus is 50 cm. So this specimen of indarctos is similar in size to large Ursus ingressus  .

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[OldGreenGrolar]

Reply 5. Extinct animals seem to have heavier bones than extant animals in general (with exceptions). The smilodon populator and American lion and cave lion has more robust bones than other big cats. Therefore, I am not surprise that cave bears have more robust bones than extant bears.