Re: Revising Hou et al, 96 (very very long)

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

Jaime Headden wrote-

>   Yes, but based on what? Most of this is limb and vertebral. The skull
> is, to quote Monty Python, "Right out!". It was originally described as a
> "carnosaur" as a result of this. One must, as with *Achillobator*, regard
> the entire anatomy, and not parts of it and ignore the rest, to form the
> hypothesis. In my undertsanding, *Bagaraatan* has hardly been a stable
> posed taxon within just maniraptoriform phylogeny.

Based on the phylogenetic analyses that included Bagaraatan of course, which
placed it near the enigmosaur-paravian split-
Rauhut 2000- trichotomy with enigmosaurs and paravians
Mortimer 2000-2001- basal paravian
Longrich 2001- basal maniraptoran
Holtz 2002- basal tyrannosauroid or basal maniraptoran
Bagaraatan was NOT originally described as a carnosaur, Osmolska (1996) was
only comfortable placing it in the Avetheropoda, and suggested it might the
sister taxon of that clade.  Obviously the above authors took many parts of
its anatomy into consideration when analyzing its position, I fail to see
why you would suspect otherwise.

> <No, I meant that I don't think it is very likely that the first
> maniraptoran or first paravian was opisthopubic.  I think they were more
> likely to be propubic, or perhaps mesopubic.>
>
>   Why? I mean, based on what data besides phylogenetic hypotheses?

Parsimony and my gut feelings.  Hence just "I think", not "I propose" or "I
have evidence for".  Beipiaosaurus' preacetabular peduncle looks like the
pubis was propubic, or perhaps mesopubic.  I don't think it's certain enough
to code, but that's how it looks to me.  Patagonykus has a mesopubic pelvis,
and alvarezsaurids are thought by many to be basal paravians or even basal
maniraptorans.  My analyses place Avimimus as sister to alvarezsaurids, and
it has a barely propubic pelvis.  Add the strongly propubic Bagaraatan to
this, and you see why I feel the first maniraptoran was not opisthopubic.
Maniraptorans with opisthopubic pelvises either have more propubic
"ancestors" (segnosaurs, alvarezsaurids), or are in the troodontid +
deinonychosaur + avialan clade, which I think has a high probability of
being opisthopubic ancestrally.

> <I'm also getting irritated by people assuming Sinornithosaurus is a basal
> deinonychosaur, as I feel it's quite likely an avialan (which goes a long
> way in explaining why it is so birdlike).>
>
>   Don't get irritated when people have either different phylogenetic
> hypotheses or disagree with you. This is a "Science marches on" thing and
> taking any scientific discourse personally is the last thing that needs to
> be done. It stints science. It's not as if many of the researchers
> involved here actually take this stuff personally ... like me.

Of course I don't take it personally, and I'm not annoyed with phylogenetic
hypotheses different from mine, but when a questionable idea is taken for
granted to support a hypothesis, it is irritating.  In this particular case,
I refer to Xu et al.'s 1999 analysis that placed Sinornithosaurus as a basal
deinonychosaur.  This could still be correct, as eumaniraptoran phylogeny is
quite uncertain at this time, but the analysis had a few major problems- not
including Pygostylia, alvarezsaurids or segnosaurs, assuming
velociraptorines are monophyletic, in addition to not including relevent
taxa described since then (Achillobator, Bambiraptor, Microraptor).  So when
people say that because Sinornithosaurus was so birdlike and a basal
deinonychosaur, deinonychosaurs were obviously evolving away from the
Archaeopteryx-like condition, I want to ask them "but what if
Sinornithosaurus is actually closer to birds than deinonychosaurs?".

> I do think that
> the precise semilunate shape of oviraptorids' fused distal carpal was
> probably convergent with paravians, but that the presence of such a large
> bone formed by the fusion of distal carpals I and II is synapomorphic in
> enigmosaurs and paravians.>
>
>   _I_ get annoyed with "I think" statements without support or
> corroboration. If it's there, I'd like to see such statements qualified,
> otherwise this opinion is nest to meaningless.

Fam had no justification for his statement either, I was just replying with
my opinion.  Again, it's based on parsimony.  Basal oviraptorosaurs and
Protarchaeopteryx have non-semilunate carpals, but oviraptorids have a
semilunate shape.  What could upset things is Beipiaosaurus, which is said
to have a semilunate identical to Deinonychus, and thus truly semilunate.

Mickey Mortimer