Re: SVP Preview

[longrich@alumni.princeton.edu]

On Wednesday, September 25, 2002, at 05:18 AM, Mickey Mortimer wrote:
> Longrich presents his "NGMC 2124 is not Sinosauropteryx" hypothesis.
> Instead it is more derived, related to Coelurus, Compsognathus and
> Ornitholestes.  Sinosauropteryx is said to be more basal, close to
> Allosaurus.  He suggests the presence of striping can be observed in the
> integument.  Yangchuanosauria is defined as all closer to 
> Yangchuanosaurus
> than Aves.  Looks like a junior synonym of Carnosauria to me, but who 
> knows
> what support he has....
	It was Mick Ellison at the Mexico SVP who suggested to me that the 
stripes were a real feature of the animal (they are most definitely 
there although mainly on the NIGP half of the animal) just to give 
credit where it is due. This sounds remarkable but it isn't- Feduccia's 
book shows a Green River dragonfly with color patterns on the wings and 
I've seen striping in the tail of a Green River bird. I picked up some 
"devil's toenails" (Mancos Shale oysters of genus... hell, I'm a vert 
guy, I'm happy just to know its a mollusk) out in central Utah and 
washed them off in the sink and was rather surprised to note... stripes 
(this is a published phenomenon incidentally so I'm not just seeing 
stripes everywhere). Also someone showed me a book on Chinese invert 
fossils from Liaoning and they show all sorts of color patterns like 
stripes and spots in the insects. So it is very possible that the 
stripes are just that; lamentably the larger specimen has the distal 
tail broken off, but the proximal tail shows banding on the underside. 
That's too much coincidence for me personally. The big question is... 
why no dark feather traces on the underside of the body? Was it 
ventrally unfeathered or were the feathers light, i.e. countershaded?
	re: phylogenetics I haven't argued that NGMC is related to any of 
those guys except in the general grade, rather than clade, sense. I 
can't think of a single good synapomorphy that would unite any of them 
(with a couple possible characters maybe possibly uniting a 
Coelurus-Compsognathus group), but they all seem to fall roughly at the 
same level of the tree. We just don't know, but unfortunately the 
tendency to lump 2124 with Sinosauropteryx, and then this chimera 
Sinosauropteryx with Compsognathus, has put us farther from knowing 
exactly what was going on. I wouldn't be surprised if it was related to 
one of the three, I wouldn't be surprised if it wasn't, either. 
Yangchuanosaurs... not tons of evidence. I just wanted to emphasize the 
hypothesis that Yangchuanosaurus, Sinraptor et al. are more basal than 
Allosaurus. Though I may be jumping the gun a bit on this, I think a lot 
of the evidence for allosauroid monophyly is arguable. Its worth noting 
that a number of important characters conflict with allosauroid 
monophyly. Yangchuanosaurs apparently had a fully enclosed pubic 
obturator fenestra, a fourth metacarpal, a low, massive astragalar 
ascending process which is more reminiscent of _Torvosaurus_ than 
_Allosaurus_, and caudal hyposphene-hypantra articulations. I'd disagree 
with some of Tom's characters, e.g. there is a tyrannosaur dorsal I've 
seen illustrated (I think it was Makovicky's thesis) with an anteriorly 
inclined neural spine so I don't think that's an allosauroid 
synapomorphy. The large lateral exposure of the antorbital fossa might 
argue for allosauroid monophyly, although the pneumatopores included 
within may not (you can't have pneumatic invasion of the nasal without 
that antorbital fossa, so I figure the character is "inapplicable" to 
anything without it).
	 I'll be upfront and say that I haven't had the chance to study 
skulls in depth so I really can't say too much there, but I think 
they're a bit overrated for higher-level systematics. Hips and ankles 
are where it's at, in that they tend to be highly conservative at the 
family level, from what I can tell although I just try to be honest and 
code everything I can confidently and objectively assign a 1 or 0 to. I 
don't believe that more characters is necessarily better, since by the 
time you get to the end of looking for characters, most of the good, 
easy, obvious ones are gone so to get that extra ten or fifty I'm often 
scraping the barrel for a bunch of subjective, highly variable stuff. I 
may actually end up with fewer characters this year than last. What I 
have done is look at bones. Lots and lots of them.