[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: [dinosaur] Hesperornithoides, new paravian from Late Jurassic of Wyoming (free pdf)

Nice work (and apologies for the belated post).  The hypothesis
consistent with this work is that powered flight (i.e. aerial
locomotion that employs both lift and thrust) evolved at least four
times in paravian theropods: _Archaeopteryx_ (Archaeopterygidae),
_Rahonavis_ (Unenlagiinae), _Microraptor_ (Microraptorinae), as well
as the line that led to extant birds (Aves).  All had feathered wings,
and were quite possibly capable of a stationary take-off plus short
bursts of powered flight.

(Scansoriopterygidae would be a fourth 'experiment' in aerial
locomotion -  they had membranous wings, and don't seem to have been
capable of a ground-to-air launch, though further work is needed - and
in progress - regarding their potential flight capabilities.)

Note that if other non-avialan paravians are inferred to be volant,
and are found *not* to be the sister taxon to any of the above, then
these would represent yet more lineages that achieved flight
independently.  _Alcmonavis_ and _Bambiraptor_ (as juveniles) come to
mind.

The hypothesis that multiple paravian lineages took to the air
independently is much more parsimonious than the alternative: that
basal paravians were volant, and multiple lineages (such as
troodontids and dromaeosaurines) lost flight independently.

Previous work has inferred that the paravian _Halszkaraptor_ also used
its forelimbs in locomotion - not aerial flight, but swimming
(specifically wing-propelled subaquatic locomotion).  It's therefore
possible that the swim stroke and the flight stroke each evolved from
the same precursor motion of the forelimb (rather than 'de novo').
This motion could have been used by terrestrial paravians for
non-flying/non-diving purposes (such as for leaping, or sharp turns,
or courtship, or prey capture, etc).  So although basal paravians may
not have been primitively volant, a forelimb motion that led to
powered flight and wing-propelled diving might be primitive for
paravians.  Thus, paravians might have been 'primed' for powered
flight, in combination with other factors (small body size; relatively
large wings; powerful hindlimbs to help get them into the air).

Finally, we really need a name for the clade that includes crown Aves
and other basal avialans (_Confuciusornis_, _Jeholornis_, etc), but
not Scansoriopterygidae. This clade is recovered in the event that
Avialae includes scansoriopterygids but not _Archaeopteryx_ (as found
by Hartman et al.).  We have Ornithes for the _Archaeopteryx_ + crown
clade (Martyniuk 2012), but this is explicitly defined to include
_Archaeopteryx_.  There's Orthavialae, which was presented by Ji et
al. (2002) in a "sketchy cladogram" (their words) as excluding
_Archaeopteryx_, but including _Jeholornis (= _Shenzhouraptor_) and
more crownward avialans, but I don't know if Orthavialae was defined.
 Also, it's a stupid name.




On Thu, Jul 11, 2019 at 12:51 AM Ben Creisler <bcreisler@gmail.com> wrote:
>
>
>
> Ben Creisler
> bcreisler@gmail.com
>
> A new paper with free pdf:
>
> Hesperornithoides miessleri gen. et sp. nov.
>
>
> Scott Hartman, Mickey Mortimer, William R. Wahl, Dean R. Lomax, Jessica 
> Lippincott & David M. Lovelace (2019)
> A new paravian dinosaur from the Late Jurassic of North America supports a 
> late acquisition of avian flight.
> PeerJ 7:e7247
> doi: 
> https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.7717_peerj.7247&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=K2P9e0K5suv1yz99dL1RLm0LC4A5ZYO3q_eMPMyyJPw&e=
>  
> https://urldefense.proofpoint.com/v2/url?u=https-3A__peerj.com_articles_7247_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=v9dm1NgLNYUVsSiaKFIkqRxS7cT2PddJ3tMY2JQL6rI&e=
>  
>
> Free pdf:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__peerj.com_articles_7247.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=f8Lavr-gR_0yG4jd88ELU9MM17TC1BVtAXdOyRwTzMg&e=
>  
>
> Supplementary information:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__dfzljdn9uc3pi.cloudfront.net_2019_7247_1_Supplemental-5Fphylogenetic-5Fdata.doc&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=xCRo_oSYIaOu_7G-HUAxARQ42iw55yl9E-tVKKlCxRo&e=
>  
>
>
>
> The last two decades have seen a remarkable increase in the known diversity 
> of basal avialans and their paravian relatives. The lack of resolution in the 
> relationships of these groups combined with attributing the behavior of 
> specialized taxa to the base of Paraves has clouded interpretations of the 
> origin of avialan flight. Here, we describe Hesperornithoides miessleri gen. 
> et sp. nov., a new paravian theropod from the Morrison Formation (Late 
> Jurassic) of Wyoming, USA, represented by a single adult or subadult specimen 
> comprising a partial, well-preserved skull and postcranial skeleton. Limb 
> proportions firmly establish Hesperornithoides as occupying a terrestrial, 
> non-volant lifestyle. Our phylogenetic analysis emphasizes extensive 
> taxonomic sampling and robust character construction, recovering the new 
> taxon most parsimoniously as a troodontid close to Daliansaurus, Xixiasaurus, 
> and Sinusonasus. Multiple alternative paravian topologies have similar 
> degrees of support, but proposals of basal paravian archaeopterygids, avialan 
> microraptorians, and Rahonavis being closer to Pygostylia than 
> archaeopterygids or unenlagiines are strongly rejected. All parsimonious 
> results support the hypothesis that each early paravian clade was 
> plesiomorphically flightless, raising the possibility that avian flight 
> originated as late as the Late Jurassic or Early Cretaceous.
>
> ===
>
>
> News and blogs:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__theropoddatabase.blogspot.com_2019_07_lori-2Dpublished-2Dmeet-2Dhesperornithoides.html&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=6y4CtU-U7zA2gGHYKBBXvcBIOtU5_aL3Kk00VMjWdyA&e=
>  
>
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.skeletaldrawing.com_home_introducinghesperornithoides&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=0oGUGloT1-aRdQikfxRh1gtOvwkXCjDjRz3S4g4SxR4&e=
>  
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.smithsonianmag.com_science-2Dnature_discovery-2Draptor-2Ddinosaur-2Dadds-2Dnew-2Dwrinkle-2Dorigin-2Dbirds-2D180972588_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=XWOs24I-IPzBQJvbqZVgdy1yOwZnP7EryPtm8uATDyQ&e=
>  
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nationalgeographic.com_science_2019_07_new-2Ddinosaur-2Dspecies-2Dvelociraptor-2Dcousin-2Dlori-2Dmay-2Dupend-2Dflight-2Devolution-2Dtheories_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=vTrD0xGT8s9aJDBajizbSscoH2d8g4uqj9btVm79sA0&e=
>  
>
> ***
>
> Podcast interview with Dean Lomax
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__onthefossilrecord.podbean.com_e_special-2Depisode-2Dthe-2Dnew-2Ddinosaur-2Dhesperornithoides_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IELF53AiFTb5P32eMniOWEZu9h7DkW8mlT2Kcjiz-Zc&s=ABGAokOgU6rWMvEMoRyknTIG0oBnKDsQkFJJ_Wh1v5E&e=
>  
>
>
> Virus-free. www.avg.com