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Re: Propatagium reveals flying ancestry of oviraptorosaurs (new Feduccia & Czerkas paper)

At the end of the 20th century, a certain A. Feduccia described
propatagia in sifakas (_Propithecus_), a kind of lemur that exhibits
aerial behavior (possibly even true gliding) (e.g., Feduccia, 1996;
Geist & Feduccia, 2000).  Nowhere was it mentioned in these studies
that the presence of a propatagium indicates powered flight ability in
sifakas, or that sifakas were descended from animals with flight
ability.  Yet, when propatagia turn up in maniraptorans, according to
Feduccia/Czerkas the presence of propatagia somehow proves these
animals could fly or were descended from animals that could fly (i.e.,
'neoflightless' / secondarily flightless).

If maniraptorans did have propatagia, it merely indicates that they
*might* have engaged in aerial behavior of some kind.  But this is
something that we've inferred anyway from the morphology of the
plumage.  By itself, a propatagium means almost nothing.  Asymmetric
feathers do not automatically indicate powered flight, although it's
likely indicative of some kind of aerial ability (e.g., Feo et al.,
2015).  The same is true of propatagia.

On Fri, Mar 20, 2015 at 1:13 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> A new paper:
> Alan Feduccia & Stephen A. Czerkas (2015)
> Testing the neoflightless hypothesis: propatagium reveals flying
> ancestry of oviraptorosaurs.
> Journal of Ornithology (advance online publication)
> DOI: 10.1007/s10336-015-1190-9
> http://link.springer.com/article/10.1007/s10336-015-1190-9
> Considerable debate surrounds the numerous avian-like traits in core
> maniraptorans (oviraptorosaurs, troodontids, and dromaeosaurs),
> especially in the Chinese Early Cretaceous oviraptorosaur Caudipteryx,
> which preserves modern avian pennaceous primary remiges attached to
> the manus, as is the case in modern birds. Was Caudipteryx derived
> from earth-bound theropod dinosaurs, which is the predominant view
> among palaeontologists, or was it secondarily flightless, with volant
> avians or theropods as ancestors (the neoflightless hypothesis), which
> is another popular, but minority view. The discovery here of an
> aerodynamic propatagium in several specimens provides new evidence
> that Caudipteryx (and hence oviraptorosaurs) represent secondarily
> derived flightless ground dwellers, whether of theropod or avian
> affinity, and that their presence and radiation during the Cretaceous
> may have been a factor in the apparent scarcity of many other large
> flightless birds during that period.