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Re: tiny theropod on a tree trunk question

David Peters (davidrpeters@earthlink.net) wrote:

<Does it make any difference to its progeny (subsequent lineage) if a tiny
theropod were to choose to grapple a tree trunk in the head up or head down
position? I was wondering this in relation to the posterior rotation of the
carpus, which would seem to be accented in the head down position and not so
much in the head up traditional grappling configuration.>

  Balance issues? Woodpeckers and squirrels (the latter more than the former,
actually) are the only animals I know of, aside from arthropods, that typically
crawl around head-down on vertical clines.

  And what posterior rotation of the carpus?

  Squirrels are capable of crawling on trucks because the ankle can
hyperpronate and is excessively flexible (along with the carpus, which is
typical of mammals to pronate, but in squirrels at least is more extremely
flexible), whereas birds that do "trunk-climbing" use a zygodactylous pes and
their tail to form a "third leg". Parrots use their beaks instead of the tail.


Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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