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Re: Rahonavis; sickle claws
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:
> [...] Deinonychus ant[ir]rhopus [...]
Sorry, happens when perception lags behind twiddle fingers.