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- Subject: Re: Catch-22
- From: Don Ohmes <firstname.lastname@example.org>
- Date: Thu, 24 Nov 2011 11:03:43 -0500
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On 11/24/2011 7:23 AM, K Kripchak wrote:
If the answer is yes; what were those traits that allowed them to
climb into the trees?
Primarily claws, especially on the fore-limbs, and small size (arbitrary
number = < 1kg) -- long toes, too.
As climbing down is actually more difficult than climbing up, and
typically involves a long jump, or series of jumps, in vertical-climbers
like cats -- feathers that serve to slow descent velocities when jumping
out of trees are also useful, even when not yet incorporated into wings.
Which reminds me -- has anyone seen video of a juvenile hoatzin
*descending*? Can't find a thing online...
As to why would they climb -- only food acquisition (foraging) and
refuge come to mind.
Barring special cases like date palms, efficient foraging in a tree
(even herbivory) requires movement through the entire tree, and even
from tree-to-tree -- and negotiating/exploiting smaller flexible (and
smooth) branches requires grasping ability that can be readily seen in
So arboreal foraging can be ruled out as a primary lifestyle in
Avoiding the negativity that accrues to those who "hide under the
shrubbery" (e.g., ants, mites, and predators) by using a suitable tree
as a sleeping place/refuge does not require grasping ability, "mammalian
flexibility" or anything other than minimal climbing ability -- and
suitable trees abound in most environments.
Therefore, however annoying it may be -- there are no selective
pressures to further specialize the pes in vertically-climbing animals
that merely roost in trees and forage/display/nest on the ground --
contra intuitive "evolutionary" arguments that roosting "is a locomotor
activity" that inevitably results in a reversed hallux, even in the face
of daily selective events that conserve the optimized cursorial foot.
Hence the lifestyle leaves little or no evidence in the bones of
cursorial animals beyond an apparent ability to climb (or fly).
Ground foraging tree-roosting (GFTR) animals are not to my knowledge
traditionally or appropriately classified as arboreal, contra the posts
implying that they are. Indeed, the American Wild Turkey cannot even be
said to be scansorial, as they have no climbing adaptations whatsoever,
and in fact cannot climb.
Unlike Archie and his ilk -- at least on that we have consensus. Archie
could climb well enough to roost.
- From: K Kripchak <firstname.lastname@example.org>