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Re: Paravian claw studies



Denver Fowler <df9465@yahoo.co.uk> wrote:


> Claws alone don't tell you as much as looking at the complete foot (and 
> preferably, the whole animal).


Yes, definitely.


There is a typological element to all this.  Because certain workers
have already made up their minds that certain fossil critters were
arboreal (such as _Archaeopteryx_ and _Microraptor_), they tend to
view certain of their characters as indicative of arboreal behavior -
including the orientation of the hallux (first toe) or shape of the
claws.  Alternative interpretations get left on the cutting room
floor.  (When I say "certain workers" I have the Feduccia/Burnham
types in mind, not GSP.)


> Basal paravians have a subarctometatarsalian metatarsus; a cursorial 
> adaptation; both we (Fowler et al, 2011) and Dececchi & Larsson 2011
> raise this point.


The arctometatarsalian pes is an adaptation found in cursorial
theropods.  But I wonder if it is a cursorial adaptation per se.  The
arctometatarsalian condition is thought to be associated with the
transmission of forces along the proximodistal axis of the pes,
resulting in a more effective dispersal of force across the mesotarsal
joint.  This would certainly be useful in a cursorial biped.  But this
character (and the less specialized subarctometatarsalian condition)
might also be useful to theropods that habitually landed on the ground
from heights.  This does not necessarily indicate arboreality.  What
if small predatory paravians clambered up onto prey much larger
themselves (or climbed a trunk to access small prey on a branch), and
then had to get back to the ground by leaping into the air?







Cheers

Tim