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Hey folks. One of my last emails of all time.. boo-hoo.
I haven't really been following this hyper-extendable claw thread, but a few
things. (1) Because dinosaur claws were - almost without doubt - made of the
same material as the claws of extant animals (i.e. keratin sheath), they were
subject to the same properties; (2) Keratin structures dull and go blunt when
abraded; (3) If is was - and presumably it _was_ - advantageous for a sickle-
clawed theropod to keep sharp tips to its claws, it would not have permitted
them to become abraded; (4) Therefore, combined with the morphological evidence
from pedal phalanges, we can we very near certain that dromaeosaurids and other
sickle-clawed theropods kept their sickle-claws raised.
Sean C wrote..
> No extant cursorial animal that I'm aware of has a pedal claw shaped like a
> dromaeosaur claw.
Extant seriemas (family Cariamidae) have a sickle-claw on a hyperextendable
digit almost indistinguishable from that of a small sickle-clawed theropod. Jim
Farlow informed us all about this quite recently. And recent discoveries of
certain fossil birds, in particular the psilopterids (possible phorusrhacoid
relatives), show that they bore dromaeosaurid-like sickle-claws too. Dr. Farlow
posted the ref for this on the list, so it's in the archives (it was reported
in _Ameghiniana_ - I bet I haven't spelt that right). But is this convergence,
"Ferocious gorilla-like living specimens of Palaeolithic man are found not
infrequently on the west coast of Ireland and are easily recognised by the great
upper lip, bridgeless nose, beetling brow with low growing hair and wild and
- - Madison Grant, _The Passing of the Great Race_ (1916)