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Re: The Very Very Latest Paper From 2006!!!
Restating-- Large animals have low surface mass ratios, and therefore lose
heat more slowly on a mass specific basis than smaller animals. It follows
that direct ambient temperature effects on growth are more pronounced in
small animals more than large, and LAGs would therefore be less defined in
larger animals, and would disappear entirely at some size.
If any temperature has an influence on bone growth, then it's the
temperature of the bone itself. Small mammals work harder tthan large ones
at maintaining their body temperature constant and high -- but despite the
higher cost they still succeed. Therefore we don't have any reason to expect
more LAGs in small than in large mammals.
However, despite this expectation, the largest mammals apparently _have_
fewer LAGs than smaller ones. So this must have another reason; I guess the
speed of growth.
Due to the obvious seasonal effects on food intake of herbivorous animals,
Good idea, but doesn't explain why elephants have fewer LAGs.
Also-- To change the subject slightly, would endotherms show a
proximal/distal limb bone LAG definition gradient?
I'd expect that endotherms with long, slim legs living in a seasonal climate
would show more LAGs in distal bones. That's because such legs have inbuilt
heat exchangers: the distal parts, which contain tendons but more or less no
muscles, approach ambient temperature, so I'd expect them to stop growing in
winter, while the proximal parts don't even stick out from the body wall and
approach body core temperature.
However, this expectation, too, is wrong AFAIK.