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Re: Oviraptorosaurs as prehistoric "peacocks"



Ben Creisler <bh480@scn.org> wrote:

> SHAKE YOUR TAIL FEATHERS: THE FLAMBOYANT, ATHLETIC, AND POSSIBLY
> FLIRTATIOUS CAUDAL MORPHOLOGY OF OVIRAPTOROSAURS. PERSONS, Walter,
> University of Alberta, Edmonton, AB, Canada; CURRIE, Philip, University of
> Alberta, Edmonton, AB, Canada; NORELL, Mark, American Museum of Natural
> History, New York, NY, USA


>From the abstract:


"These new finds show that pygostyles and, by
associational inference, tail-tip feather-fans were widespread amongst both
advanced and primitive oviraptorosaurs."


It's worth noting that confuciusornithids and enantiornitheans have a
pygostyle, but the tail feathers do not form a fan.  AFAIK, within the
bird clade, rectricial fans are limited to the
Ornithuromorpha/Euornithes lineage.


In confuciusornithid and enantiornithean specimens that preserve large
tail-feathers, these feathers are ribbon-like and used for display.
No tail-fan.  This includes _Confuciusornis_, _Changchengornis_,
_Eoconfuciusornis_, _Protopteryx_, _Paraprotopteryx_, _Eoenantiornis_,
_and _Longirostravis_. There may also be small "fuzzy" tail-feathers
preserved - but never a tail-fan.  This is odd, because at face value
it implies that the pennaceous rectrices of long-tailed "birds"
(archaeopterygids, jeholornithids) were lost, but then regained as a
rectricial fan in the line that led to modern birds (but not by
Enantiornithes).


Alternatively, the rectrices ("rectricial frond") of long-tailed bird
transformed directly into a rectricial fan in the
ornithuromorph/euornithean clade, and the lack of a rectricial fan in
confuciusornithids and enantiornitheans was due to secondary loss of
the rectrices by confuciusornithids and enantiornitheans
independently.  If confuciusornithids and enantiornitheans form a
clade (to the exclusion of basal birds and crown birds), then this
loss occurred only once.  However, there is currently no phylogenetic
support for a Confuciusornithidae+Enantiornithes clade.  It'll be
interesting to see if _Sapeornis_ had a tail-fan.






Cheers

Tim