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Re: SICKLE-CLAWED DINOSAURS
<...how do you properly define a sickle claw? Cassowaries, as everyone
on the list should now be aware, have an elongate, very sharp claw that
they use as a slashing/stabbing weapon - it is not kept raised off the
ground, and is not sickle-shaped.>
*Borogovia* and *Adasaurus* lack any great movement of digit II along
the phalangeal joints and the ungual, like both the advanced
dromaeosaurids and troodontids do. This is also true of *Dromaeosaurus*,
where the claw is small and may have been laid flat, as the claw was not
as recurved as later forms, and so less prone to being dulled.
Troodontids like *Saurornithoides* had small claws, but they were
recurved almost as strongly as dromaeosaurs, and the phalangeal joints
were strongly circular, rather than semi- as in *Borogovia*,
*Adasaurus*, and *Dromaeosaurus*.
<Meanwhile, a number of birds of prey (true raptors) have an enlarged,
sickle-shaped claw on digit II. In falconids this is sometimes kept
raised when the bird is perched.>
Add _many_ passerines to that group. From crows to robins to ovenbirds
there is an enlarge digit II and claw that almost looks like it is used
as a weapon (or could be - I'm not saying it is).
Jaime A. Headden
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