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Vorona and Sickle Claws



Ekaterina Amalitzkaya (eamalitz@hotmail.com) wrote:

<Vorona was said to be a sickle clawed bird. I have been of the
impression that only Archaeopteryx and Rahonavis had these
sickle claws and that the trait was lost by the time of the
enantiornithine radiation. Vorona was said to be a typical
enantiornithine there was no reason to believe otherwise. So  is
this sickle claw merely an error of Mr. Keesey or some new
material of Vorona that has become available? [...] Finally has
evidence for this claw ever turned up in oviraptorosaurus?>

  Purportedly there is new Mascarene material for *Vorona
berivotrensis,* however it is unbdescribed. Hopefully it will
strengthen some hypotheses of enantiornithean relationships. The
type and paratype material as such as having been described
lacks the sickle claw, or even phalanges of the pes.

  But on that note, Ekaterina asks about sickle claws in that
fave group of mine, oviraptorosaurs. So, to quibble, the answer
is yes and no. :)

  1) Oviraptorosauria as defined using the original PT
definition, includes all theropods closer to *Oviraptor* than to
birds (Padian and Hutchinson, 1997; Chiappe, 1997; Padian
Hutchinson and Holtz, 1999) as well as the competing definiton,
*Oviraptor* <= *Ornithomimus*, which would have virtually the
same content; that makes some other interesting animals
oviraptorosaurs, including therizinosauroids! And that makes
them the biggest maniraptorans ever. At least regarding ovi +
segno relationships, which as recent threads suggest, some
people disaggree with that. I can certainly sympathize, these
are really bizarre animals! Anyway, the pes of all
Therizinosauroidea as far known have very narrow and strongly
recurved claws, larger more medially, so that the first (hallux)
digit has the biggest claw, the second next, and so on. In this
way, they have sickle claws. But the intermediate phalanges are
not extensible, nor are they slender, but short, thick, and
weight-bearing.

  2) Oviraptorosauria contains strictly only animals closer to
*Oviraptor* than to birds, ornithomimosaurs, or therizinosaurs.
These oviraptorosaurs lack any form of recurved claws: they are
wide, flattened ventrally, and only *Conchoraptor* seems to have
recurved claws. The pes is distinctly sub-cursorial, and the
digits can be as long or longer than the pes itself, which would
indicate locomotion on soft, porous or fluvial substrate, as in
sand, mud, very wet and gooey or shifty substrates, etc. These
feet are not in any way predatory.

  So, to expand, the groups of dinosaurs for which a sickle claw
or extensible claw is known is as follows (an "*" markes those
for which an extensible claw is known):

  *       Dromaeosauridae [of course]
  *       Troodontidae
  [no *]  Therizinosauroidea + *Beipiaosaurus*
  *       Noasaurus leali
  *       Ligabueino andesi [but, no claw is known, but is
          inferred from *Noasaurus*]
  [no *]  Many raptorial birds and passeriforms have large
          second toe claws, but these are not held off the
          substrate.
  [?]     Archaeopteryx (A. lithographica and A. bavarica)
          [Paul suggests that the claw was extensible, other
          workers who have looked for the features suggest the
          phalanges are either not indicating this
          extensibility, or the phalanges were inverted upon
          observation; I have no opinion on the subject]
  [?]     Confuciusornis sanctus [this taxon may have a
          extensible claw, but the claw itself does not appear
          to be "raptorial" or sickle-shaped]
  --      Just to be concise, many arhcosaurs (like
          crocodyliforms) have enlarged, recurved pedal claws,
          superficially sickle-like, but these pedes are
          terrestrial essentially, and may have been used only
          to dig with.

  If anyone would like to elaborate, please feel free :)

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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