Indarctos oregonensis

[Deleted]

It seems we have a contender for one of the largest bear: link.springer.com/article/10.1007/s10914-021-09546-9

Look at the size of this humerus:

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

Can someone evaluate the length of this bone please?

[Deleted]

Citations from the paper:

the humerus is enormous, being larger than any living bear and representing the largest known humerus for the genus.

With a length of 362.54 mm, the huge mandible from Ft-40, Nebraska represents the largest mandible of all Indarctos and among the largest mandibles of all bears, rivaled only by the largest individuals of Ursus spelaeus (Baryshnikov 2007), Arctotherium angustidens (López et al. 2008) and “Agriotherium schneideri” (personal observation). The cheek teeth of this mandible are surprisingly small for its size, but the canines are huge and the individual probably represents an old male.

[brobear]

WORLD'S RECORDS BLACK BEAR:
Greatest length of skull without lower jaw: 14 12/16
Greatest width of skull: 8 14/16
SCORE: 23 10/16

WORLD'S RECORDS GRIZZLY BEAR:
Greatest length of skull without lower jaw: 17 4/16
Greatest width of skull: 10 9/16
SCORE: 27 13/16

WORLD'S RECORDS ALASKA BROWN BEAR:
Greatest length of skull without lower jaw: 17 15/16
Greatest width of skull: 12 13/16
SCORE: 30 12/16

WORLD'S RECORDS POLAR BEAR:
Greatest length of skull without lower jaw: 18 8/16
Greatest width of skull: 11 7/16
SCORE: 29 15/16

Ursus Ingressus
Greatest Length: 571.4mm
Mastoid Width: 255.6mm
Total Score: 827mm or 32.56 inches

Arctotherium Angustidens
Condylobasal Length of the Skull: 402.8mm (n=11; range: 364-430mm)

The largest skull for any bear that we have on record is from Ursus ingressus with an (estimated) total score of 38.08 inches:

The second largest skull that we have on record up to date is from Simus and it has a total score of 35.15 inches: 
 
domainofthebears.proboards.com/thread/696/skulls  

(Indarctos) With a length of 362.54 mm (14.27 inches)

[Deleted]

Here we are talking about the mandible, not the condylobasal length. Look at the size of this mandible, it is huge. The humerus is larger than any cave bear humerus i have seen, look carefully  .
This mandible belongs to one of the largest bear ever.

[brobear]

Original Paper
Published: 25 May 2021
Coexistence of Indarctos and Amphimachairodus (Carnivora) in the Late Early Hemphillian of Florida, North America

link.springer.com/article/10.1007/s10914-021-09546-9

Abstract
Fossils of the ursid Indarctos from Withlacoochee River 4A of Florida (late early Hemphillian North American Land Mammal Age, Hh2, ~ 7.5–6.5 Ma) represent the best sample of this genus in North America, including both craniodental and postcranial specimens, yet only the skull has been described. In this study, we describe the other material of this bear from the same locality and review the records of Indarctos in North America. Indarctos from Withlacoochee River 4A has dental characters in accordance with those of typical Indarctos oregonensis, but has distinctly more slender postcranial bones. Indarctos from other localities of North America contains two morphs with regards to postcranial robustness, but lacks a clear geographic pattern. Indarctos from Withlacoochee River 4A shares traits with the Old World Indarctos zdanskyi and may be its descendant in the New World. The machairodont from Withlacoochee River 4A shows typical characters (e.g., presence of distinct P4 preparastyle and mandibular flange) that allow referral to Amphimachairodus rather than to Nimravides. Its morphology also shows a stronger affinity of this population to the Old World Amphimachairodus horribilis rather than to Hh3 Amphimachairodus coloradensis. Previously, most North American records of Amphimachairodus were late Hemphillian (Hh3–4, ~ 6.5–4.5 Ma), when it co-occurred with a different ursid, “Agriotherium.” The Withlacoochee River 4A specimens provide evidence that Amphimachairodus dispersed from Asia during the Hh2. The special morphology of Indarctos and the presence of Amphimachairodus in a Hh2 fauna suggest that the environment had begun to change before the significant fauna turnover between the early and late Hemphillian.

[brobear]

Indarctos oregonensis Merriam et al., 1916

www.gbif.org/occurrence/787072806

See images on this site.

[brobear]

JOHN DAY FOSSIL BEDS NATIONAL MONUMENT
Indarctos oregonensis
Indarctos oregonensis, a short faced bear

www.nps.gov/media/photo/gallery-item.htm?id=89369942-EFC3-04EF-BED735A07565DC77&gid=8923EDAD-FAAC-0617-70AD453759354C9C

Artwork: 
              

[brobear]

Northern Florida bear fossils reveals new species of Indarctos in North America

timescavengers.blog/2022/07/27/northern-florida-bear-fossils-reveals-new-species-of-indarctos-in-north-america/

Coexistence of Indarctos and Amphimachairodus (Carnivora) in the Late Early Hemphillian of Florida, North America

Qigao Jiangzuo · Richard C. Hulbert Jr.

What data were used? ~ 7.5–6.5 million year old Indarctos fossils from the Withlacoochee River 4A Formation in Northern Florida, USA. These fossils were compared to previously collected specimens from elsewhere in the United States and China.

Methods: This work descriptively compared ~ 7.5–6.5 million year old Indarctos fossils form Northern Florida with corresponding Indarctos fossils from formations in Kansas, Texas, Oregon, California and Nevada. Additionally, fossils from Northern China were reviewed to connect a possible ancestral relationship.

Results: This study investigated at least four Indarctos individuals found in the Withlacoochee River 4A Formation of Florida. As it is uncommon to find numerous individuals in one site, this fossil find marks one of the most comprehensive groupings of Indarctos fossils in in North America. These four individuals made it possible for the researchers to compare jaw, dental, neck, pelvic, and heel properties between the specimens at the formation and other Indarctos fossils worldwide. The similarities in dental characteristics between Indarctos of the Withlacoochee River 4A formation and I. oregonensis, a species of Indoarctos, paired with differences in slenderness of postcranial bones between the Florida specimens and I. oregonensis (skeleton excluding the skull) shows a at least two variations of postcranial bones in North America. What does this mean about the Florida Indoarctos? Is it a new species? This works makes no definite support or rejection of the Indarctos of the Withlacoochee River 4A Formation being a previously unknown species, but acknowledges the need for further research to determine this. 
   
Why is this study important? This study shows a possible unique species of Indarctos that hasn’t previously been identified. Indarctos throughout North America show a differing type of bone robustness, despite not being geographically separated. This work documents that Indarctos may have ancestors in northern China, showing a possible movement to North America from Eurasia in the geologic past. This work, paired with fossils of other fauna (animals) and climatic data, may be able to show shifts in ecosystems as a driver in the migration of Indarctos.  
 
The big picture: New fossil finds strengthen understandings of how organisms moved across the globe in geologic time. The information gained form comparing Indarctos fossils provides insight into how other mammals may have moved.

[brobear]

Figure 1: Top, bottom, and side views of a Indarctos skull fossils from the Withlacoochee River 4A in northern Florida (A1-3) and a I. zdanskyi from Baode in north China (B1-3). 
                                      

[brobear]

Aug 20, 2022 16:56:30 GMT -5 @hibernours said:

Here we are talking about the mandible, not the condylobasal length. Look at the size of this mandible, it is huge. The humerus is larger than any cave bear humerus i have seen, look carefully  .
This mandible belongs to one of the largest bear ever.

Can we find some mandible fossils of cave bears and giant short-faced bears for comparison? Perhaps also of brown bears and polar bear. 
This could prove to be quite interesting.

[brobear]

May 10, 2017 0:59:51 GMT -5 brobear said:

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 ).

From May 10, 2017

[Deleted]

Thanks brobear. The images you posted in reply 6 are old images and probably not accurate because if we look at the humerus in the paper, it represents a very robust bear, more robust than any Ursus spelaeus i have seen.
The images you posted from wildfact doesn't reflect the largest specimens. See my comparison in the thread Indarctos size: domainofthebears.proboards.com/thread/877/indarctos-size?page=1&scrollTo=59202

Do you realize that if Indarctos is confirmed to have a humerus surpassing any living bear, we have potentially a bear that can reach 1000kg for the largest specimens? It is a possibility but at least we have real material to work with.

[brobear]

Yes, those images are from 2017. Thank you for your research, hibernours. I'm anxious now to learn more.