Polar bear bone density exceeds that of brown bear

[Deleted]

Does anyone agree with this data above?

[grrraaahhh]

I'm always interested in specimen details. I will answer more later.

[grrraaahhh]

The old adage: The Devil is in the Details. Chew on or digest the following:


(Specimen Review)


NMNH 123386 (Ursus arctos)

nhb-acsmith2.si.edu/emuwebvzmammalsweb/pages/nmnh/vz/DisplayMammals.php?irn=7246192&QueryPage=%2Femuwebvzmammalsweb%2Fpages%2Fnmnh%2Fvz%2Frotation_masterMammals.php

NMNH 275124 (Ursus maritimus )

nhb-acsmith2.si.edu/emuwebvzmammalsweb/pages/nmnh/vz/DisplayMammals.php?irn=7295464&QueryPage=%2Femuwebvzmammalsweb%2Fpages%2Fnmnh%2Fvz%2FDtlQueryMammals.php



Details on the brown bear is limited. NMNH data tells us it was an adult male bear weighing 330 lbs, while the polar bear was female. Compare the brown bear specimen with the following NMNH 301690 Yellowstone National Park (YNP) grizzly bear sow which weighed 500 lbs. It appears we are looking at a young adult boar. For follow up morphological data on interior and arctic North American brown bears, please visit the URSUS ARCTOS HORRIBILIS & BROWN BEAR section under the North America menu in the EXTANT BEAR PROFILES (IN DEPTH) section.


RE: polar bear and brown bear, remember, the polar bear (whose diet is 90% meat) grow larger. Only mature specimens from the largest of brown bear populations where meat input is historically high are comparable to them as it relates to size.


Ignoring the equation/formula used to estimate bone density, instead, take a deeper look at the other terrestrial and aquatic specimen values for example the Indian rhino, African lion, and walrus. If you are really interested in this material, go ahead and look up additional specimen info used in this study and share your results.


So what do we need to know about the article? Well, W.P. Hall (the article author) thesis contends/states, "Increased bone density is highly correlated with aquatic habits in mammals." According, to Hall, aquatic wildlife that live in a submerged existence produce the highest bone density values when compared to their terrestrial counterparts. An interesting argument, although the specimen material examination (at a quick glance) leaves a lot more to be desired. To tie it in with the brown bear and the polar bear; the brown bear is often foraging for food (a lot of digging, moving stones/boulders, or den construction) while the more maritime polar bear (besides swimming) hunts seal primarily by breaking/puncturing thick ice. In short, there is a lot of dynamic forelimb activity coupled with large active hunting territory (see both hind-limbs and forelimb activities). IMO, corresponding bone density values plus quantitative sampling visa vi mature/prime male polar bears or boar brown bears (regardless of population) would be very interesting to look at.

[grrraaahhh]

In case other members are not aware, the OP was citing the following article: Hall, P. William. The Correlation between High Limb-Bone Density and Aquatic Habits in Recent Mammals (1983). J. Paleont. 2:197-207.

[warsaw]

Oct 16, 2011 23:43:52 GMT -9 @ultrahybrid said:

Does anyone agree with this data above?

What is a conclusion from data ?
Anyway.I totally agree with what grrraaahhh said .

[Deleted]

Full apologies for not posting the references as I have been busy during that time. They will be coming hopefully in a few days.
The information talks about the bone density that semi aquatic animals genrally have higher bone density compared to fully terrestrial animals.
In conclusion, the polar bear being a semi-aquatic animal has denser bones than the brown bear.
I am not sure wheather higer bone density equals more muscle mass. Some might say so others will disagree.

Edit: The reference has already been posted by grraaahhh, my bad for not noticing.