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Re: Vorona and Sickle Claws

David Marjanovic (david.marjanovic@gmx.at) wrote:

<The South American enantiornithean *Yungavolucris* has a
tarsometatarsus* with a distally thickened and medially
diverging mt II. May this have borne a sickle claw?

*AFAIK this is all what is known of *Yungavolucris*>

  A bunch of metatarsi, yes, I beleive. However, the
tarsometatarsus is unique in being very broad, short, and
robust, resembling sphenisciforms to some degree aside from the
shorter metatarsal II, which may or may not support a special
digit. The fourth metatarsal is equally unique in lacking a
trochlea and being condylar in form, which suggests that the toe
was mobile to some degree. So without actual digits, that's all
that can be suggested. My personal observation is that the pes
belongs to an aquatic form of stem avisaurid (I would use
Avisauroidea for this group: {*Yungavolucris* + *Lectavis* +
*Avisaurus*} ) that is distinct from both sphenisciform or
hesperornithiform in having a very short second metatarsal,
subequal third and fourths, and possibly more robust medial
digits than lateral....


Jaime A. Headden

  Where the Wind Comes Sweeping Down the Pampas!!!!

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