Re: Rahonavis; sickle claws

[Gerrit Hanenburg <G.Hanenburg@inter.NL.net>]

At 22:43 26-11-2001 +0100, you wrote:

> > But seriemas have curved claws on pedal digit III and IV too. [...]
> > So, what is the difference with regard to size and degree of claw
> > arc curvature between digit II and the others in seriemas?
>
>        *Confuciusornis sanctus* (fine specimen in the same museum) likewise
> has distinctly enlarged claws II (curved as expected in a perching bird).
> Neither relative size nor curvature are as extreme as in "dromaeosaurs" and
> *Rahonavis* (hey, come to think of it, I don't know enough about
> troodontids...). I can't tell whether the toe was hyperextensible (means, I
> can't see greatly enlarged articular surfaces, means, _I think_ it was not).

I seriously doubt that. There are a number of Confuciusornis foot specimens 
illustrated in Chiappe et al. (1999: 47-49). I see no significant 
differences between the unguals of digit II and the others. In one specimen 
(GMV-2130) digit III even appears to be larger than II. And they explicitly 
state that "Confuciusornis sanctus lacks the predatorial specializations of 
digit II seen in Rahonavis ostromi (Forster et al., 1998a, b) and retained 
to a lesser degree in certain more advanced birds, such as Patagopteryx 
deferrariisi." (p. 47).

Chiappe, L.M. et al. (1999). Anatomy and Systematics of the 
Confuciusornithidae (Theropoda: Aves) from the Late Mesozoic of 
Northeastern China. Bulletin of the American Museum of Natural History 242: 
1-89.

> > [...] Deinonychus ant[ir]rhopus [...]

Sorry, happens when perception lags behind twiddle fingers.

Gerrit