Re: Revising Hou et al, 96 (long)

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

Tim Williams wrote-

> Mickey is a nice guy, but here he's being overly charitable.  :-) The
> new possible Yixian dromaeosaurid (BPM 1 3-13) shows structures along
> its limbs and tail which could only be regarded as true feathers: these
> structures have a rachis and barbs, conforming to the pinnate morphology
> of modern feathers (as known for _Caudipteryx_, _Protarchaeopteryx_ and
> birds).

I agree, the structures on BPM 1 3-13 are clearly feathers, but I'm unsure
whether the specimen is dromaeosaurid or not.  I have a rather strict
definition of the clade (Dromaeosaurus + Velociraptor), unlike the AMNH team
who described it.  The long tail suggests it may be a true dromaeosaurid,
but I'm leaving it as Eumaniraptora incertae sedis for now.

> > Chaoyangia + Ornithurae-
> > *. small pedal claws
> > This character is rejected because it is not quantified and highly
> > correlated with non-perching habits.
>
> I'm a little unclear on this point.  How so?

Some birds (confuciusornithids, Jibeinia, Boluochia, Iberomersornis,
Neuquenornis, Sinornis, etc.) have comparatively large curved pedal unguals,
while others (Patagopteryx, Yanornis, Yixianornis, Gansus, Hesperornis) have
smaller straighter pedal unguals.  The first group are all small taxa with
body plans similar to modern passerines, and in all probability spent much
of their time perched in trees.  The second group are generally larger and
occupy a variety of niches, Patagopteryx being terrestrial, Hesperornis
aquatic and Gansus, Yanornis and Yixianornis thought to be shore birds.
This is how the data looks to me at least.

> > "Cathayornis" (=Sinornis)
>
> It does?  I know this has been mooted...

Yes, as Sereno will show in the upcoming Mesozoic Birds: Above the Heads of
Dinosaurs volume.

> _Yandangornis_ is actually known from a nearly complete skeleton (ZMNH
> M1326), though the forelimbs (wings?) are mostly missing.  However,
> _Yandangornis_ is preserved in two dimensions, which unfortunately
> obscures certain anatomical details (as in specimens of
> _Archaeopteryx_).

True.  Suppose I should have said "poorly described", Cai and Zhao's effort
leaving much to be desired.  This gave it a large percentage of unknown
states in the data matrix (71%), which let it form many equally parsimonious
trees. See
http://www.cmnh.org/fun/dinosaur-archive/2001Jan/msg00565.html for more
information on this taxon.

> The entire Sauriurae-Ornithurae dichotomy is an example of not letting
> the facts get in the way of a good story.  I'm sure Mickey would agree.
> :-)
> Nice work, Mickey.

Thanks.  Your take on the Sauriurae issue is exactly right, now we just have
to wait for ABSRDers to realize it.....

Mickey Mortimer