Darwinopterus notes

[David Peters <davidpeters@att.net>]

[This was sent a few days ago, Technical glitch evidently prevented  
its reception. A few minor changes added.]

Free Darwinopterus download:

http://rspb.royalsocietypublishing.org/content/early/2009/10/12/rspb.2009.1603.full.pdf

First of all, congratulations to the Lü team for a series of  
spectacular finds. The uncovering of that tail and toe is incredible.

Second, I'm disappointed that more taxa were not included in the  
analysis. And I'm also disappointed to read this from the  
Suppplmentary Data: "The search was terminated at 500,000 trees due to  
memory limitations." That's a sign that something is wrong. The Lü  
study needs to use more of the available taxa.

Yes, Darwinopterus is, as it appears, a sort of Germanodactylus AND  
unique enough to merit it's own genus. On the same note, lots of  
nominal Germanodactylus specimens need their own genus. They have a  
wonderful untold variety.

When you include more taxa than the Lü team included, Darwinopterus  
nests nowhere near any of the four origins of the pterodactyloid  
clade. Darwinopeterus nests in the middle of several nominial  
Germanodactylus specimens and very close to the Karlsruhe specimen,  
SMNK-PAL 6592, ironically known for its long metacarpals and long  
legs. And there's a reason for that...but that involves other long- 
legged taxa.

On a happy note: I see that Scaphognathus and Dorygnathus are moving  
up the ranks, FINALLY, closing in as sister taxa to the  
Pterodactyloidea! THAT is new and THAT is starting to match earlier  
findings (published as an abstract (Peters 2007) in the Flugsaurier  
papers). Just add several tiny taxa, several specimens of Dorygnathus  
and Scaphognathus and a few dozen more characters and all will resolve  
to a single tree.

Third, while the short metacarpal/ulna ratio is VERY rare, it also  
occurs 7 taxa down from Darwinopterus in SMF a. M. No. 4072, and  
Mesadactylus by convergence and both of these have ratios atypically  
shorter than surrounding sister taxa. So such a character is not  
unique within Pterodactyloidea. I see neither tiny taxon was included  
in the Lü team study.

The reduction of the metacarpal/ulna ratio in Darwinopterus is matched  
by a rare ulna > tibia character state, also found by convergence in  
SMF a. M. No. 4072 and B St 1967 I 276 (also by convergence in  
ornithocheirids and nyctosaurs)- but in no sister taxa. So, in  
Darwinopterus (judging by surrounding Germanodactylus taxa), as the  
legs became shorter so did the metacarpals, both of which are derived  
according to the larger suite of characters.  Note: such unique  
characters are STILL not enough to make them sister taxa.

The opposite holds true for those long-legged, long-metacarpal taxa,  
but there's an untold twist in Pteranodon and Nyctosaurus.

Fourth, while the elongated pedal digit V is great to see finally  
published, you'll find similar pedal digit Vs on MOST pterodactyloid- 
grade pterosaurs when you look for them. Like Darwinopterus, most of  
these are tucked under the metatarsus. Yes, most Pteraichnus  
trackmakers have short pedal digit Vs and they all come from just a  
few clades, even so, there are some surprises.

Fifth, the long tail and fifth toe can be seen on several  
Germanodactylus specimens, but at present you have to look for the  
telltale ridge in the light matrix covering. I can send samples for  
where to look. My sense is this is a reversal in germanodactylids  
because predecessor taxa (most small forms) have a long tail, but it  
is not nearly as robust. It's wonderful that such a tail and toe has  
finally been uncovered and published. Now I don't have to explain as  
hard when I show the same in reconstructions. It's also time to take  
certain specimens off the walls and dig out the toes and tails!

I wish the Lü team best wishes and again, congratulations on a great  
and extremely important find.

David Peters
St. Louis

davidpeters@att.net