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Re: comment-therizinosaurs



On 10/11/2011 9:11 AM, Augusto Haro wrote:
Bears, being relatively smart mammals, appear to use them in a variety
of ways, for example defense, offense, turning rocks, unearthing food
(would not this mean that these blade-like unguals can be used when
digging for food, instead of cave-making?), etc..

Very long claws are not useful in applications that involve heavy loads such as digging in heavy soil or turning rocks -- they generate too much "reverse" leverage. Dogs and (I assume) bears damage their claws often, but they grow back -- claws anywhere near the 3' length cited online would damage the bones they were attached to if heavily loaded.

Defense has been mentioned -- otherwise, the reconstructions and fossils imaged online would be useful in raking leaf litter, manipulating flexible branches and maybe even grooming.

Besides, most sloths (living and fossil) I can remember do not have
strongly curved claws, so perhaps slightly curved claws are not so bad
when dealing with branches.

No, they are not so bad. Certainly the sloth analog is not kaput due to claw shape...