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Re: Avian flight stroke origin



Osteologically speaking, does a juvenile hoatzin show a greater capability for 
grasping than most maniraptorans?


-----Original Message-----
From: Tim Williams <tijawi@gmail.com>
Sender: owner-DINOSAUR@usc.edu
Date: Fri, 12 Aug 2011 16:52:48 
To: <dinosaur@usc.edu>
Reply-To: tijawi@gmail.com
Subject: Re: Avian flight stroke origin

Anthony Docimo <keenir@hotmail.com> wrote:

>  Last I checked, members of the Anteater family (or the Pangolins) lack 
> opposable halluxes or thumbs or any such things.  Yet they can sleep in tree 
> branches.


These mammals have other arboreal adaptations.  For example, the pygmy
ant-eater (_Cyclopes_), the most arboreal of the extant
myrmecophagids, have hindfeet that are highly specialized for arboreal
(especially suspensory) behavior (see Meldrum et al. 1997; Am. J.
Phys. Anthropol. 103: 85-102).  The tamandua (_Tamandua_), which
divides its time between the trees and the ground, shows a wide range
of flexion of the metacarpo-phalangeal joint, consistent with
branch-grasping.  These anteaters also have a prehensile tail.  The
arboreality of pangolins (_Manis_) vary among individual species, but
I know that a prehensile tail is characteristic of pangolins too.


> Can't we extend that possibility to maniraptors?


You don't necessarily need opposable hands or feet to be arboreal.
But you need to be able to grasp branches somehow, and maniraptorans
(aside from those avialans with an opposable hallux) do not show
adaptations for branch-grasping in either the manus or the pes.
(Although _Bambiraptor_ may be an exception w.r.t. the manus,
according to Senter, 2006.)





Cheers

Tim