Re: Coelurosaur phylogeny

[David Marjanovic <david.marjanovic@gmx.at>]

> OK, so while everyone here is arguing whether to use Segnosauria or 
> Theriznosauria, my questions are still unanswered. Basically, 
> 
> 1) Are _Compsognathus_, _Sinosauropteryx_, _Proceratosaurus_ & 
> _Ornitholestes_ considered basal maniraptors, basal maniraptoriformes or 
> basal coelurosaurs? And what is their phylogenetic placing relative to 
> tyrannosaurs & ornithomimosaurs? 
 
Yes. 
 
I don't mean to make fun of you, but nobody knows. Recent analyses (2001 
onwards) have produced all those results, IIRC. There is no consensus. 
Perhaps one will emerge after the descriptions of *Tanycolagreus* and 
"*Huaxiasaurus*" and Fred (the one that was found with *Nothronychus*), 
and after it will be cleared up where each of the specimens of 
*Sinosauropteryx* really belongs, but don't hold your breath. 
 
> 2) Are tyrannosaurs considered outside maniraptoriformes & thus 
> classified as basal coelurosaurs? 
 
Sometimes. This position seems to be pretty popular nowadays... but more 
fossils of basal tyrannosaurs wouldn't exactly hurt. For the record, I 
think tyrannosaurs have a more derived ancestry, but as I can only think 
of... 1 character to support this (the extra exit for the brain nerve V1), 
don't care. :-) 
 
> 3) Are ornithomimosaurs a part of maniraptoriformes or also basal 
> coelurosaurs? 
 
The wonders of phylogenetic taxonomy make it easy to answer this in the 
correct way -- ornithomimosaurs are by definition part of 
Maniraptoriformes. (Assuming of course that this definition will be 
repeated under the PhyloCode.) Of course this says absolutely nothing 
about what else is inside or outside Maniraptoriformes (except for birds, 
which are by definition inside). 
 
> I've come up with 3 arrangements here: 
> 
> 1) Coelurosauria includes tyrannosaurs & maniraptoriformes. 
> Maniraptoriformes includes (in order) ornitholestids, compsognathids, 
> ornithomimosaurs & maniraptors. 
 
In this case only the latter two are Maniraptoriformes if you apply the 
definition. 
 
> 2) Coelurosauria are ornitholestids, compsognathids & maniraptoriformes, 
> which is made up of tyrannosaurs, ornithomimosaurs & maniraptors. 
 
I like this most. :-) But again, this means nothing, and if 
ornithomimosaurs and maniraptors are closer to each other than the 
tyrannosaurs, then the latter are outside Maniraptoriformes. They are 
always inside Sereno's Tyrannoraptora, however. 
 
> 3) Coelurosauria is same as (2), except that compsognathids & 
> ornitholestids are basal maniraptors. 
> 
> which one is closest? 
 
42. 
 
BTW: I've included Scansoriopterygidae in my bird analysis. So far they 
love to come out next to (*Archaeopteryx* + (*Rahonavis* + 
*Shenzhouraptor/Jeholornis*)), but maybe that's only because there are no 
dromaeosaurs in there (yesterday I've added *Microraptor* but not run an 
analysis with it). But I'm pretty sure they wouldn't go away far, 
consistent with HP Mickey Mortimer's "preliminary" results of 
Scansoriopterygidae as the sistergroup to Archie + short-tailed birds. 
Evidence? For example the tail, where the middle vertebrae are over 2 x as 
long as the 1st (also in *Microraptor*). More coming, before June 3rd. 

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