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RE: Rahonavis; sickle claws
At 13:33 26-11-2001 -0600, you wrote:
Seriemas (_Chunga_ and _Cariama_) do have a sickle-claw on the second toe.
So do certain phorusrhacids (e.g. _Psilopterus_). Cariamids and
phorusrhacids are gruiform birds, so the presence of an enlarged sickle-claw
may be a shared derived feature.
But seriemas have curved claws on pedal digit III and IV too. Anyway, this
can be quantified with methods such as used by Feduccia (1993) and Ostrom
(1969). So, what is the difference with regard to size and degree of claw
arc curvature between digit II and the others in seriemas?
Feduccia, A. (1993). Evidence from claw geometry indicating arboreal habits
of Archaeopteryx. Nature 259: 790-793.
Ostrom, J. H. (1969) Osteology of Deinonychus anthrhopus, an unusual
theropod from the Lower Cretaceous of Montana. Peabody Museum of Natural
History Bulletin 30: 1-165.