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Re: SVP Preview

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.