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Re: Rahonavis; sickle claws

At 17:13 26-11-2001 -0800, Jaime A. Headden wrote:

Sickle Claws in Modern Birds

Not just a few species have very larger second pedal digit claws, however, one must realize that
in _all_ birds, either the second or the first claw is the longest. In the more terrestrial birds,
it's usually the first (hallucial) whereas some terrestrial birds (have a larger second [seen in
sereiamas, cassowaries and, I believe, kiwis and moa]). Most predatory birds and perching birds
have subequal yet very large second and first pedal claws, and the second through fourth are
strongly recurved. The first is also strongly recurved in strigiform, caprimulgiform, and
falconiform birds, as part of the raptorial specialization.

However, only one bird has been noted to have a particularly "extensible" second pedal digit,
and that's the seriama; they have been seen (I have, anyway) to have a second toe that can lift
off the ground. But no modern bird or even fossil bird has a particularly "predatory" and largest
second pedal claw, and the seriama's claw is not so recurved as to be a "true" weapon, and neither
is that of the cassowary, so they do not qualify as "sickles." I can suggest that no member of
Aves has a predatory sickle claw.

But cassowaries are definitely known to use their claws as weapons, though not for predation (they are essentially frugivorous). I've seen them do it, and the phenomenon is also well described in Handbook of Birds of the World Vol. 1 (p. 93): "An attacking cassowary raises its body and kicks out at its adversary with both feet at once, or else races past, kicking out as it goes. In such confrontations the cassowary is a formidable opponent, and the long, sharp claw on the inner toe is an extremely dangerous weapon, which can inflict a mortal wound on a dog or even a man." (though ostrich has been observed to disembowel hyaena in a similar manner). As far as I know seriemas only use their legs as weapons when kicking at each other during territorial conflict.