|
Post by brobear on Apr 22, 2020 4:21:34 GMT -5
Continued: The different interpretation had more than cosmetic implications. Christiansen and Harris suggested that this different perspective indicated that Panthera atrox was not descended from prehistoric lions which crossed into North America via the Bering Land Bridge. Instead the researchers hypothesized that Panthera atrox speciated from an earlier form of jaguar around 150,000 years ago. In this scenario, there were never any true “American lions” at all. The closest thing would have been lions which lived in the vicinity of the Bering land bridge but did not travel further south.
I have to admit, I wasn't sold on the idea that Panthera atrox was more of a jaguar than a lion. Perhaps the cat shared some lower jaw traits with jaguars and tigers, but the data from the crania, especially, indicated that the cat was more like a lion than anything else. And, after all, anatomy isn't everything when it comes to Pleistocene mammals. The skulls of Panthera atrox from La Brea may show some slight differences when held up to those of modern lions, but genetic comparisons have pinned down the fossil cat as a member of the lion lineage. That’s the fortunate thing about studies of creatures which died in the not-too-distant prehistoric past – genetic material can be collected, analyzed, and studied to further test ideas made on the basis of skeletal anatomy. In a study published the same year as that of Christiansen and Harris, zoologist Ross Barnett and colleagues reported that Panthera atrox formed a distinct genetic cluster among prehistoric lion populations which became genetically isolated around 340,000 years ago. Even more specifically, Barnett and co-authors noted “All late Pleistocene lion samples produced sequences that grouped strongly with modern lion data”, and this finding ruled out “any postulated link between [Panthera] atrox and jaguar.” What Panthera atrox was, and how the cat made a living on the late Pleistocene landscape, lies between the common images of “American lion” and “giant jaguar.” Even Christiansen and Harris noted how lion-like the cat’s skull was, and the genetic data clearly place Panthera atrox within the lion lineage. Nevertheless, there are a few curious things about the La Brea specimens that may indicate that these beasts did not act just like modern lions.
|
|
|
Post by brobear on Apr 22, 2020 4:27:22 GMT -5
Quote: "the genetic data clearly place Panthera atrox within the lion lineage." *My weird thoughts: Being within the lion lineage does not make atrox a lion. Consider that the closest living relative to the gorilla is the chimpanzee. Yet, the nearest relative of the chimp ( other than the bonobo ) is the human. Also note that the atrox is further separated from the lion than the polar bear is from the grizzly.
|
|
|
Post by brobear on Apr 22, 2020 12:06:15 GMT -5
www.ncbi.nlm.nih.gov/pubmed/28092905 Endocranial Morphology of the Extinct North American Lion (Panthera atrox)... 2017 Jan 17. The extinct North American lion (Panthera atrox) is one of the largest felids (Mammalia, Carnivora) to have ever lived, and it is known from a plethora of incredibly well-preserved remains. Despite this abundance of material, there has been little research into its endocranial anatomy. CT scans of a skull of P. atrox from the Pleistocene La Brea Tar pits were used to generate the first virtual endocranium for this species and to elucidate previously unknown details of its brain size and gross structure, cranial nerves, and inner-ear morphology. Results show that its gross brain anatomy is broadly similar to that of other pantherines, although P. atrox displays less cephalic flexure than either extant lions or tigers, instead showing a brain shape that is reminiscent of earlier felids. Despite this unusual reduction in flexure, the estimated absolute brain size for this specimen is one of the largest reported for any felid, living or extinct. Its encephalization quotient (brain size as a fraction of the expected brain mass for a given body mass) is also larger than that of extant lions but similar to that of the other pantherines. The advent of CT scans has allowed nondestructive sampling of anatomy that cannot otherwise be studied in these extinct lions, leading to a more accurate reconstruction of endocranial morphology and its evolution.
|
|
|
Post by King Kodiak on Oct 12, 2020 9:50:07 GMT -5
Panthera atrox: body proportions, size, sexual dimorphism, and behavior of the cursorial lion of the North American plains
Body Mass
Calculations of body mass were performed as specified in the methods. Results differ by method
and by element (Table 5B). Van Valkenburgh’s (1990) regression of m1 APD on body mass appears to
be the most reliable, as it most closely approximates the average of all methods.
Overall, the smallest body mass value for female Panthera atrox is 89 kg and the largest is 262
kg; male values are 156 kg and 457 kg. The overall average is 177 kg for females and 247 kg for males.
Males are thus estimated to be 1.40 times larger than females.
We determined a mean weight of 178 kg for wild P. leo males and 141 kg for females using
recent data from Sunquist and Sunquist (2002) and established values from the body mass literature (Van
Valkenburgh, 1990) as shown in Table 5B. The average determination using these methods yields extant
males 1.26 times larger than females. As the underlying measurements are significantly different between
sexes, it is no surprise that the calculated body weights for P. atrox are also significantly different between sexes.
www.researchgate.net/publication/281544339_Panthera_atrox_body_proportions_size_sexual_dimorphism_and_behavior_of_the_cursorial_lion_of_the_North_American_plains
|
|
|
Post by brobear on Oct 12, 2020 9:55:30 GMT -5
178kg = 392.42 pounds. ( P. leo male ). 247kg = 544.54 pounds. ( P. atrox male ).
|
|
|
Post by King Kodiak on Oct 12, 2020 10:03:49 GMT -5
The largest they found was a 457 kg (1007 lbs). That is huge.
|
|
|
Post by OldGreenGrolar on Oct 12, 2020 10:10:11 GMT -5
The largest they found was a 457 kg (1007 lbs). That is huge. That is larger than an exceptionally large male smilodon populator and slightly lighter than an average male polar bear on Foxe Basin. Regardless, a male polar bear has stronger deltoid muscles than a male smilodon populator and american lion.
|
|
|
Post by brobear on Oct 12, 2020 16:14:52 GMT -5
The largest they found was a 457 kg (1007 lbs). That is huge. We must keep in mind; all weights of prehistoric animals are estimations.
|
|
|
Post by King Kodiak on Oct 12, 2020 16:27:22 GMT -5
The largest they found was a 457 kg (1007 lbs). That is huge. We must keep in mind; all weights of prehistoric animals are estimations. Yeah definitely, for sure.
|
|
|
Post by brobear on Nov 26, 2020 2:20:30 GMT -5
The largest they found was a 457 kg (1007 lbs). That is huge. We must keep in mind; all weights of prehistoric animals are estimations. I would like to see the measurements on this atrox. If we could compare his head-and-body length to that of a coastal brown bear, then we could safely judge whether or not this number is an over-estimation.
|
|
|
Post by theundertaker45 on Nov 26, 2020 2:24:18 GMT -5
brobear The largst specimen of Panthera Atrox is estimated to have ranged between 250-260cm in HB-length (straight line). The largest coastal brown bears have a total length of ~280cm over the curves which would correspond to a straight line length of ~250cm.
|
|
|
Post by OldGreenGrolar on Nov 26, 2020 2:37:40 GMT -5
The American lion in addition has the biggest skull out of all cats 😎. Ferox posted that picture on another thread.
|
|
|
Post by brobear on Nov 26, 2020 7:18:47 GMT -5
brobear The largst specimen of Panthera Trox is estimated to have ranged between 250-260cm in HB-length (straight line). The largest coastal brown bears have a total length of ~280cm over the curves which would correspond to a straight line length of ~250cm. So, basically any difference in head-and-body length would likely be a matter of several inches, one way or the other.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 27, 2020 17:02:59 GMT -5
|
|
|
Post by theundertaker45 on Nov 27, 2020 17:16:50 GMT -5
@cheetah No, the original source they used in this study dates back to an outdated work making use of single-bone equations not taking the overall average ratios of bones into account. That's a common flaw in many older works as only one specific bone was being looked at and all the other data was being adjusted to it instead of taking the overall average measurements/ratios of limb bones and then adjusting it. This results in both grossly underestimated and grossly overestimated body masses. It's like taking one specific bone of a specimen and assuming that all other bones of the same species must have the exact same proportions regarding their measurements, it doesn't work like that. Applying the most reliable equations on the American lion (taking the average of a larger sample of bones into account) we would be at an average weight range of 251-266.2kg for males with an absolute min-max. range of 199-351kg. I'll link a discussion on "Wild Fact" under this comment here where they are talking about this (Reply #13 is of utmost importance): wildfact.com/forum/topic-american-lion-panthera-atrox
|
|
|
Post by brobear on Nov 27, 2020 17:18:45 GMT -5
This involves a huge amount of reading. Where exactly does this site give the weight of P. artox?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 28, 2020 14:45:11 GMT -5
@cheetah No, the original source they used in this study dates back to an outdated work making use of single-bone equations not taking the overall average ratios of bones into account. That's a common flaw in many older works as only one specific bone was being looked at and all the other data was being adjusted to it instead of taking the overall average measurements/ratios of limb bones and then adjusting it. This results in both grossly underestimated and grossly overestimated body masses. It's like taking one specific bone of a specimen and assuming that all other bones of the same species must have the exact same proportions regarding their measurements, it doesn't work like that. Applying the most reliable equations on the American lion (taking the average of a larger sample of bones into account) we would be at an average weight range of 251-266.2kg for males with an absolute min-max. range of 199-351kg. I'll link a discussion on "Wild Fact" under this comment here where they are talking about this (Reply #13 is of utmost importance): wildfact.com/forum/topic-american-lion-panthera-atroxInetersting,Is there a proper refutation paper for the study I sent?Also guate does not include the study I sent.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 28, 2020 14:46:36 GMT -5
brobear do ctrl+f and type weight you will find it
|
|
|
Post by theundertaker45 on Nov 28, 2020 14:49:02 GMT -5
@cheetah
The refutation is Reply #13 in the thread I linked; he goes in detail on everything including the study you mentioned (Anyonge, 1993) and explains why their estimations produced such grossly overexaggerated figures.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 28, 2020 16:08:27 GMT -5
theundertaker45In reply 13 that is just some words from guate,it is not a proper refutation like Sorkin I believe but he calls them wrong for using a particular equations,have these equations been proved wrong?
|
|