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Re: Jeholornis: Two-Tailed Wonder

Just when I thought Mesozoic birds couldn't get any weirder... a bird
with "two tails".  So not really two tails, but a proximal "fan" and a
distal "frond".  But still weird.

I think it's worth entertaining the possibility that _Jeholornis_
didn't actually fly.  Maybe the aerodynamic feathers (remiges and
"fan") were used for purely ground-based behaviors.  Or for returning
to earth after climbing a tree (such as a bennettite or gingko) to
forage, similar to what Dyke &c recently proposed for _Microraptor_.
Either way, the aerodynamic feathers would be employed principally for
control and maneuverability rather than for any behavior that
qualifies as powered or sustained flight.



On Tue, Oct 8, 2013 at 1:40 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> From: Ben Creisler
> bcreisler@gmail.com
> Many thanks to Jason for posting the new Jeholornis paper.
> Note some additional information:
> Free supplementary pdf with photos:
> http://www.pnas.org/content/suppl/2013/10/02/1316979110.DCSupplemental/pnas.201316979SI.pdf
> News stories:
> http://news.nationalgeographic.com/news/2013/10/131007-two-tailed-dinosaur-bird-jeholornis-paleontology/
> http://www.newscientist.com/article/dn24335-prehistoric-avian-had-unique-dualpurpose-tail.html#.UlNvi1B6YYE
> On Mon, Oct 7, 2013 at 6:44 PM, Jason Brougham <jaseb@amnh.org> wrote:
>> News today of a more proximal tail fan in Jeholornis:
>> Jingmai O’Connor, Xiaoli Wang, Corwin Sullivan, Xiaoting Zheng, Pablo 
>> Tubaro, Xiaomei Zhang, and Zhonghe Zhou
>> Unique caudal plumage of Jeholornis and complex tail evolution in early 
>> birds PNAS 2013 ; published ahead of print October 7, 2013, 
>> doi:10.1073/pnas.1316979110
>> We describe the presence of essentially two functional tails in the Early 
>> Cretaceous Jeholornis (the second most primitive bird)—one like that of some 
>> modern birds with a fan-shaped tract of feathers over the proximal tail 
>> vertebrae and another distal frond like that of feathered dinosaurs such as 
>> Caudipteryx and Microraptor. We suggest that the unique “two-tail” plumage 
>> in Jeholornis probably evolved as the result of complex interactions between 
>> natural and sexual selective pressures and served both aerodynamic (flight 
>> and balance, etc.) and ornamental functions (communication/display, etc.). 
>> Our aerodynamic analysis also provides a plausible functional explanation 
>> for the elongation of the boney tail in Jeholornis relative to Archaeopteryx.
>> http://www.pnas.org/content/early/2013/10/02/1316979110.abstract?sid=8ba0510d-473b-46ef-9aa7-b4dcf8d88096