Re: New gliding reptile: Mecistotrachelos

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

Just so as not to give a false impression: as usual, I agree with everything 
I don't comment.

> Fraser also notes that closely related forms (Icarosaurus,  Kuehneosaurus, 
> and Kuehneosuchus) DO have exceptionally elongate  thoracolumbar ribs AND 
> markedly elongate transverse processes.  (Emphasis mine)

(Obvious because you didn't put any quotation marks anywhere.)

> The only problem is, (phylogenetically) elongate transverse processes
> are no where else to be found in ANY sister taxa near or semi-far.

They had to evolve at _some_ point. They have to be an autapomorphy of 
_some_ clade. In other words, _some_ clade that has the feature will have a 
sister-group that lacks it.

> What that means is, the 'markedly elongate transverse processes ARE  the 
> ribs, straightened and fused to the vertebrae for (one could  readily 
> assume) strength and stability as they anchor the 'wings'.

No, it doesn't mean any such thing. Compare *Draco*, which has elongate 
transverse processes that articulate with lengthened ribs. Also note that 
*Coelurosauravus* has a lot more neomorphic rods than ribs, which is how the 
fact that they aren't ribs was discovered in the first place.

> And that means the 'wings' are, as in Coelurosauravus, still  supported by 
> folding neomorphic ossifications. As a matter of fact,  in Icarosaurus at 
> the transitional dorsal vertebrae -- the ones not  supporting neomorph 
> ossifications between the scapulae -- this fusion  is visible because it 
> is incomplete. Heck, these lines are even drawn  on the 1970 Colbert 
> restoration that Fraser's group includes!!!!

OK, I'll try to dig up that paper tomorrow.

> 1) a pointed snout (in ventral view).

Plesiomorphy.

> 2) not having a good understanding of the fossil itself (a Photoshop 
> tracing and a reconstruction in various views should always be  attempted 
> because it opens your eyes to new possibilities, especially  in 
> low-contrast situations such as this)

Rather, you should take the _fossil_ and try various methods of _lighting_: 
different angles, different strengths, perhaps UV...

> 3) not having a good understanding of the phylogeny of the Reptilia
> (Mecistotrachelos is NOT an archosauromorph, BUT a lepidosauromorph).

We'll maybe believe that when your paper to this effect will have passed 
peer-review. I'm not saying the current view is set in stone, I'm saying I 
have yet to see evidence that it's wrong.

> Coelurosauravus (Permian) has 23 ossified rods. The first 11 are  bundled 
> proximally and emerge from the second and third dorsal rib.  The 
> remainder, 12-23, are each associated with a rib tip

How precise is that association? -- I'll try to look it up.

> Icarosaurus (Triassic) has 13 ossified rods, all of which are
> associated with rib tips that look like transverse processes.

And articulate with the "rib tips" in the same way that ribs articulate with 
vertebrae, right...?

> Mecistotrachelos has 9 ossified rods, all of which are associated
> with rib tips that look like transverse processes. The first ossified
> rod is very short, no longer than one dorsal vertebra.

That sounds like a cervical rib to me.

> Is this a valid genus? Yes. IMHO. Based on ossified rod element
> numbers and cervical length principally.

Genera are a feel-good affair. You could always declare it a subgenus or 
even just a species of *Icarosaurus*. Nobody can stop you. :-)