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RE: Yurgovuchia, new dromaeosaurid from Utah



Interesting that the authors sink Linheraptor into Tsaagan.  No evidence is 
given, and they commit a pet peeve of mine, in sinking a species into a genus, 
so Linheraptor exquisitus becomes Tsaagan sp..  Which not only is improper, as 
you can't just destroy species, but unecessary since Linheraptor only has one 
named species.

The phylogenetic analysis is Senter's (2011, based on Senter 2010 which is 
based on Senter 2007), with several taxa added.  One of these is Xiaotingia, 
which makes this a partial test to see if Archaeopteryx stays a deinonychosaur 
when paravians Senter didn't include are added.  The authors importantly add 
Sinusonasus (from Senter, 2010), Austroraptor, Mahakala, Shanag and 
Tianyuraptor, which leads to Archaeopteryx being an avialan as usual.  See what 
I meant about waiting for other analyses to confirm Xu et al.'s finding before 
accepting it?  Also contra Xu et al., Anchiornis and Xiaotingia aren't 
archaeopterygids and don't form a clade, with the former remaining a troodontid 
as in Senter (2010) and the latter being a basal dromaeosaurid.  Still not 
included are Balaur, Pedopenna, Jinfengopteryx, IGM 100/1128, Jixiangornis, 
Dalianraptor or Yandangornis among important basal paravians.  What will the 
Lori analysis say?  We'll have to see...

Mickey Mortimer

----------------------------------------
> Date: Tue, 15 May 2012 16:03:00 -0700
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Yurgovuchia, new dromaeosaurid from Utah
>
> From: Ben Creisler
> bcreisler@gmail.com
>
> A new theropod in PLoS ONE:
>
>
> Senter, P., Kirkland, J.I., DeBlieux, D.D., Madsen, S. & Toth, N. (2012)
> New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous
> of Utah, and the Evolution of the Dromaeosaurid Tail.
> PLoS ONE 7(5): e36790.
> doi:10.1371/journal.pone.0036790
> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0036790
>
>
> Background
>
> The Yellow Cat Member of the Cedar Mountain Formation (Early
> Cretaceous, Barremian? – Aptian) of Utah has yielded a rich theropod
> fauna, including the coelurosaur Nedcolbertia justinhofmanni, the
> therizinosauroid Falcarius utahensis, the troodontid Geminiraptor
> suarezarum, and the dromaeosaurid Utahraptor ostrommaysorum. Recent
> excavation has uncovered three new dromaeosaurid specimens. One
> specimen, which we designate the holotype of the new genus and species
> Yurgovuchia doellingi, is represented by a partial axial skeleton and
> a partial left pubis. A second specimen consists of a right pubis and
> a possibly associated radius. The third specimen consists of a tail
> skeleton that is unique among known Cedar Mountain dromaeosaurids.
>
> Methodology/Principal Findings
>
> Y. doellingi resembles Utahraptor ostrommaysorum in that its caudal
> prezygapophyses are elongated but not to the degree present in most
> dromaeosaurids. The specimen represented by the right pubis exhibits a
> pronounced pubic tubercle, a velociraptorine trait that is absent in
> Y. doellingi. The specimen represented by the tail skeleton exhibits
> the extreme elongation of the caudal prezygapophyses that is typical
> of most dromaeosaurids. Here we perform a phylogenetic analysis to
> determine the phylogenetic position of Y. doellingi. Using the
> resulting phylogeny as a framework, we trace changes in character
> states of the tail across Coelurosauria to elucidate the evolution of
> the dromaeosaurid tail.
>
> Conclusions/Significance
>
> The new specimens add to the known diversity of Dromaeosauridae and to
> the known diversity within the Yellow Cat paleofauna. Phylogenetic
> analysis places Y. doellingi in a clade with Utahraptor, Achillobator,
> and Dromaeosaurus. Character state distribution indicates that the
> presence of intermediate-length caudal prezygapophyses in that clade
> is not an evolutionarily precursor to extreme prezygapophyseal
> elongation but represents a secondary shortening of caudal
> prezygapophyses. It appears to represent part of a trend within
> Dromaeosauridae that couples an increase in tail flexibility with
> increasing size.