RE: Ah ha! That's where therizinosaurs came from

[Jaime Headden <qi_leong@hotmail.com>]

  I like to think of *Oviraptorosauria* as a clade (*Oviraptor philoceratops* 
Osborn, 1924 < *Passer domesicus* Linnaeus, 1758) [including the first, 
excluding the last -- although a more complete listing would use a few more 
exclusive specifiers]. If so, it would automatically include anything that 
could find its way into a sister-group relationship with "basic" 
oviraptorosaurs. This would mean coining new names for the internal "former 
oviraptorosauria" clade, but that's a non-issue: We can easily coin a name for 
each major node in the stem's content (by which I mean robustly supported and 
non-labile, supported by most divergent analyses), and clade (*Scansoriopteryx 
heilmanni* Czerkas & Yuan, 2002 + *Oviraptor philoceratops* Osborn, 1924) would 
be one of these. Cau's "greater Oviraptorosauria" suggestion would require 
instead treating the classic name as a node, so that adding taxa as sisters to 
the clade would allow one to name more and more external nodes. The stem idea 
is very useful and effective, and I see no issue with departing from it.

  Xu et al. is only a recent analysis, and I would wait for more robust support 
before assuming its topology is useful to name nodes/stems for. In the same 
light, we are hesitant about following Maryańska et al (2002) and Osmólska et 
al. (2004) as, in their analyses, various differences between them and the TWG 
analyses result in distinct positions for various key taxa. While I am more 
prone to follow the TWG analyses (including Xu et al.) in general, new 
topologies with low posterior probability support (such as the new position of 
*Archaeopteryx lithographica*) make me VERY wary as we add in new data and 
exclude various potentially useful taxa (note that several important basal 
"dromies" and "troodonts" were not present in that analysis which have been 
used by others to move several taxa around). Paul's work eschews cladistic 
methodology, and is hardly comparable; consider that the one attempt he 
presented to support his eschewing of this process was to present a phyletic 
analysis supporting a non-theropodan position for *Erlikosaurus andrewsi* and 
*Segnosauridae* in general [with *Therizinosaurus cheloniformis* "clearly" 
being a theropod] -- paraphrasing his use of the term, the analysis was 
"maroon-ic."

  It should be noted that I was supportive in general of the clade 
(*Therizinosaurus cheloniformis* Maleyev, 1954 + *Oviraptor philoceratops* 
Osborn, 1924) but was hesitant not just about naming the clade, but supporting 
what was accidental nomenclature in general. This clade has not been showing up 
in larger analyses than when it first appeared, especially with use of 
*Falcarius utahensis* in the analysis, and because of this I am even less 
supportive of passing nomenclature for clades due to incidental analyses. The 
final element of my wariness is that positional support for many of these are 
not based on actual shared autapomorphies, but ACCTRAN/DELTRAN adjusted data 
that are lost in posterior probability adjustments, and are generally 
plesiomorphic or homoplastic.

  Were sufficient analysis with strong posterior support and non calibrated 
features be found where the transformations are not apparently homoplastic to 
support placing any scansoriopterygid and/or sapeornithid within 
*Oviraptorosauria*, I would welcome it as I do any new clade topology, save 
that it should be supported by another analysist's different matrix. To my 
knowledge, strong numbers of data and taxa appear in Andrea Cau's analysis -- 
but that is in Andrea's, not Xu's or anyone else's of comparable numbers -- and 
as is noted in the pre-print version of Naish et al. (unpublished), 
*Archaeopteryx lithographica* is not clearly supported as a deinonychosaur 
exclusive of *Avialae*, as from the position in the strict concensus cladogram: 
http://3.bp.blogspot.com/-eEL7rVmxUNM/TjbHglm3hGI/AAAAAAAADSo/XrDTPC_wlRE/s1600/Samrukia-SOM-Theropoda-tree-as-jpg.jpg
 
[http://theropoda.blogspot.com/2011/08/il-ritorno-della-fenice-samrukia.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+blogspot%2FaJKG+%28Theropoda%29].

  Based SOLELY on the postcranial anatomy, I find (as I did when I conflicted 
with Mickey WAAAY back in 2002 when we were competitively ratcheting our 
analyses) scansoriopterygids likely to be non-avialaeans. I do not find this 
likely for ANY sapeornithid. If strong weight is placed on the cranial features 
that were suggestive of various affinities between various sapeornithids and 
oviraptorosaurs to the exclusion of postcranial, then their analysis is in 
clear error. It also doesn't help that both *Scansoriopteryx heilmanni* and 
*Epidendrosaurus ningchengensis* are based on apparent non-adults, while this 
does not seem to be the case for *Epidexipteryx hui*. Eventually, I'll get to 
talk about this in more detail.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


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> Date: Sat, 13 Aug 2011 01:25:05 +0200
> From: david.cerny1@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Ah ha! That's where therizinosaurs came from
>
> Jaime Headden <qi_leong@hotmail.com> wrote:
>
> > I have a hard time seeing sapeornithids (any of them) as oviraptorsaurs. 
> > The skulls (e.g., Zhou & Zhang, 2003) are superifically similar (and by 
> > superficially, I mean cherry-picking specific oviraptorosaurs and ignoring 
> > others, like for example *Incisivosaurus gauthieri*) but seem to differ in 
> > the details, or are represented broadly among maniraptorans, like 
> > *Scansoriopteryx heilmanni* (Czerkas & Yuan, 2002) and *Epidexipteryx hui* 
> > (Zhang et al. 2008).
>
> Andrea Cau has proposed a clade (named "Magnoviraptorosauria")
> containing not only oviraptorosaurs and sapeornithids, but
> scansoriopterygids as well. Given that Xu et al. (2010) supported a
> sister group relationship between scansoriopterygids and
> oviraptorosaurs to the exclusion of sapeornithids and Paul (2010)
> argued for a link between oviraptorosaurs and sapeornithids (with
> scansoriopterygids as _Coelurosauria_ incertae sedis), it may be or
> become the best explanation for the problem. The distribution of skull
> characters you mention seems to support it.
>
>
> References:
>
> http://theropoda.blogspot.com/2010/06/coming-soon-flying-oviraptorosaurs-from.html
>
> http://theropoda.blogspot.com/2010/06/test-su-magnoviraptorosauria.html
>
> Paul GS 2010 The Princeton Field Guide to Dinosaurs. Princeton:
> Princeton Univ Press. 320 p
>
> Xu X, Ma Q-Y, Hu D-Y 2010 Pre-_Archaeopteryx_ coelurosaurian dinosaurs
> and their implications for understanding avian origins. Chin Sci Bull
> 55: 1-7
> --
> David Černý