Re: Japanese dromaeosaur

["Ralph W. Miller III" <gbabcock@best.com>]

Mike Hickman wrote:

> I have Don's book and I have seen said claw, it is quite large to my
> understanding but what I would like to know is the exact measurements of
> the claw if anyone knows them.

My recollection is that said photograph of the Japanese dromaeosaur terminal
ungual pedal phalanx #2 included a metric ruler for scale.  Based on this, I
calculated the reconstructed bone to be about 15.3 cm measured around the
outside curve, based on an extrapolated distal tip (broken off in the
specimen).  That's about 6 1/4 inches.

Gregory S. Paul writes in _The Complete Illustrated Guide to Dinosaur
Skeletons_ that the keratin sheath on claws (as well as on spikes, plates,
and beaks) probably lengthened them by about 33% to 100% beyond the length
of the bone itself.  Given the pronounced curvature of most dromaeosaur
claws, I would recommend a conservative keratin covering length.  On the
other hand, if, as some propose, these claws were characterized by sharp
undersides, then there must have been sufficient ventral keratin sheath
material to produce such an effect, as the dromaeosaur claw bones I have
seen do not taper to a blade-like edge ventrally.   Ultimately, Ray
Stanford's as yet unpublished dromaeosaur tracks laid down in deep mud (if
such they be), which reportedly feature impressions of the raised sickle
claw, may help in restoring dromaeosaur claws to their approximate length
and sharpness.

The Japanese dromaeosaur "sickle" claw depicted appears to be a bit larger
than large _Deinonychus_ unguals, but smaller than the _Utahraptor_ ungual.
Of course, there is no telling if the recovered specimens represent the
largest individuals of these genera that lived, particularly with small
sample sizes.  And I may simply be unaware of the size of recovered
_Deinonychus_ unguals that are larger than the Japanese dromaeosaur.

-- Ralph W. Miller III       gbabcock@best.com