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Re: Planet Dinosaur Ep 2



Augusto Haro <augustoharo@gmail.com> wrote:


> Or how the raptorial claw
> of dromaeos was hypothesized to be for climbing instead of attacking
> prey (either stabbing or slashing).


Yes, the "crampon" hypothesis for the dromaeosaur sickle-claw proposes
that it was specialized for gripping, rather than for stabbing or
stabbing.  This fits with the climbing abilities inferred for
microraptorines.  However, in the case of large eudromaeosaurs such as
 _Velociraptor_ and _Deinonychus_ the sickle-claw would have been used
to help grip large prey, along with the forelimbs, while the jaws went
to work.


In the words of Manning et al. (2005):

     "We envisage dromaeosaurs leaping onto live prey
      and establishing footholds on the latter’s flanks using
      the piercing/gripping functions of their pedal digits in
      combination with the grasping recurved claws on the
      manus. The sharp, finely serrated teeth of dromaeosaurs
      (Ostrom 1969, 1990; Norell & Makovicky 2004) could
      then have inflicted many wounds on their prey, while
      firmly locked onto the latter’s flanks."


On this basis, it'd be useful to examine the sickle-claws of derived
troodontids (like _Talos_ and _Linhevenator_).  With their short arms
and more gracile build, the same predatory strategy as proposed for
_Velociraptor_ etc is unlikely for these troodontids.  In the
troodontid _Borogovia_ the ungual on the second toe was actually
straight, not sickle-shaped.





Cheers

Tim