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Re: [dinosaur] Jianianhualong, new feathered troodontid from Lower Cretaceous Jehol Group of China (free pdf)

Just finished a quick read through of this paper. It is a neat specimen and a 
generally well-written paper. The idea that feather vane asymmetry might be 
quite basal is very interesting (albeit not terribly surprising). 

My one criticism at the moment is that while the authors cite the most 
important literature regarding the relevant dynamics related to feather 
asymmetry, they don’t really use that literature effectively. The paper, as 
written, implies that the dynamics of feather asymmetry aren’t well understood. 
Contrary to this suggestion, the basics of asymmetrical vane twist and stall 
reduction are known, and the key paper on the subject (Feo et al., 2015) is 
even cited in this manuscript - but only as support for the statement that 
asymmetry is complicated! I feel that this oversight matters, because the 
difference between functional asymmetry and anatomical asymmetry could play 
into the phylogenetic patterns that the rest of the paper is primarily 
concerned with.

Plotting the appearance of feather vane asymmetry in the tail and forelimbs in 
a phylogenetic framework was a great idea, but I do wish the authors had 
plotted both anatomical asymmetry (as they did) and aerodynamic asymmetry 
(which they did not).

I’d be curious to hear what others think of the manuscript.



Michael Habib, MS, PhD
Assistant Professor, Integrative Anatomical Sciences
Keck School of Medicine of USC
University of Southern California
Bishop Research Building; Room 403
1333 San Pablo Street, Los Angeles 90089-9112

Research Associate, Dinosaur Institute
Natural History Museum of Los Angeles County
900 Exposition Blvd, Los Angeles, CA 90007

(443) 280-0181

> On May 2, 2017, at 9:57 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> A new paper in open access:
> Free pdf:
> Xing Xu, Philip Currie, Michael Pittman, Lida Xing, Qingjin Meng, Junchang 
> Lü, Dongyu Hu & Congyu Yu (2017)
> Mosaic evolution in an asymmetrically feathered troodontid dinosaur with 
> transitional features
> Nature Communications 8, Article number: 14972 (2017)
> doi:10.1038/ncomms14972
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_articles_ncomms14972&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=VNxchIqWbg5Av5JX9LDpOvu9xBh0fjY3NjNT-nKsktE&s=-_ph7ku7I_2srBqkrisbBR4dgN7hi9G8DxQ53ADxUeI&e=
> Asymmetrical feathers have been associated with flight capability but are 
> also found in species that do not fly, and their appearance was a major event 
> in feather evolution. Among non-avialan theropods, they are only known in 
> microraptorine dromaeosaurids. Here we report a new troodontid, 
> Jianianhualong tengi gen. et sp. nov., from the Lower Cretaceous Jehol Group 
> of China, that has anatomical features that are transitional between 
> long-armed basal troodontids and derived short-armed ones, shedding new light 
> on troodontid character evolution. It indicates that troodontid feathering is 
> similar to Archaeopteryx in having large arm and leg feathers as well as 
> frond-like tail feathering, confirming that these feathering characteristics 
> were widely present among basal paravians. Most significantly, the taxon has 
> the earliest known asymmetrical troodontid feathers, suggesting that feather 
> asymmetry was ancestral to Paraves. This taxon also displays a mosaic 
> distribution of characters like Sinusonasus, another troodontid with 
> transitional anatomical features.
> ===
> News: 
> https://urldefense.proofpoint.com/v2/url?u=http-3A__news.nationalgeographic.com_2017_05_fossil-2Ddinosaur-2Dtheropod-2Dfeather-2Devolution-2Ddiscovery-2Dchina_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=VNxchIqWbg5Av5JX9LDpOvu9xBh0fjY3NjNT-nKsktE&s=29b3ebixy2bLbkI7srKUq2w3HbIDitObSyn3h08IfF8&e=
> https://urldefense.proofpoint.com/v2/url?u=http-3A__gizmodo.com_this-2Dnew-2Ddinosaur-2Dlooked-2Dan-2Dawful-2Dlot-2Dlike-2Da-2Dchicken-2D1794833786&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=VNxchIqWbg5Av5JX9LDpOvu9xBh0fjY3NjNT-nKsktE&s=uFi0ufebGWRldE4I4l_uQH0QYtmkwG7H5ci7Vay9iCE&e=