Re: SICKLE-CLAWED DINOSAURS

["Jaime Headden" <jaemei@hotmail.com>]

<...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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