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re: comments on E&P of pteros
D. Unwin wrote:
If you want to have any
degree of confidence in your data (and consequently any hope of
else of the validity of your results) turn off the computer and GO LOOK
FOSSILS - its the only way.
First of all, let me mention one compliment I forgot to pass on earlier
regarding David's observations. He was exactly right in anticipating
that Preondactylus would have a higher premaxilla ascending process than
previous reconstructions showed -- more like Dimorphodon. A
reconstruction justifies David's foresight.
I have to wonder, though, about David's comment above. What will strike
the reader upon even a casual glance at his 2003 figures is that they
all appear to be copies of extant figures, rather than new drawings --
starting from scratch. The same holds true of many of David's papers,
excluding his 1988 report on Dimorphodon, which had no precedent. I have
no doubt that David has actually seen the fossils. A carefull tracing of
some or many of the fossils will reveal flaws in their precedents. A
tracing of the figures themselves will not.
D. Unwin also wrote:
I would urge those interested in this subject to read the entire paper
you will find that I commented at some length on my reasons for using
suprageneric OTU's. Yes, ultimately we should attempt to analyse
relationships at the species, or even specimen level. I have done this
generic level (which in many cases is the same as the species level) for
'rhamphorhynchoids'. The resulting cladogram was the same as that just
except with a lot more terminal taxa. This should, I hope, appear
shortly in the
Eudimorphodon symposium volume.
David's matrix has a higher proportion of filled boxes than any
preceding it, and this is one reason given for using suprageneric OTUs.
If that's the goal, then great. I still think it breeds chimaerae.
I think the pterosaur interrelations problem is more difficult than
anyone imagined two years ago when David's paper was probably due to the
publisher, but thankfully and fortunately, it appears that there now is
a critical mass of taxa to tell the tale -- if they are all employed. I
applaud David's efforts to divide the spectrum of pterosaur
interrelationships further, but I am disheartened to hear that the
cladogram will be the same as before. Mine was similar, about a year
ago, when it had a single clade "Pterodactyloidea" as all published
cladograms do now. Here's what happened: the morphological gap between
the highest rhamphs and the lowest pterodacs bothered me enough to dig
deeper, and I hope David and others do the same. Evolution works in tiny
steps and if you look hard enough you'll see the tiny steps, as I have.
I would urge future geneologists to consider a number of Dorygnathus and
Scaphognathus specimens as terminal taxa and not to consider Dory or
Scapho a single taxon each. Here is where the former 'Pterodactyloidea'
splits into four clades. Pay special attention to the manus and pedes of
each. Some reassembly will be required. In all four cases, a size
crunch follows that ultimately leads to the larger taxa we know and
love. So, here's where the wee ones make their entrance before giving
rise to the big ones. The Teyler's Museum in the Netherlands cares for
some of these key taxa.
Also pay special attention to the various Germanodactylids, and don't
forget Wellnhofer's No. 13 and No. 6 among them. This grade contains a
surprising variety and contributes to a recent split I noted between
Pteranodon + Nyctosaurus on the one hand and Dsungaripterids +
Tapejarids on the other.
Best of luck. The problems will go away with a bit more work. A single
tree is still what you're shooting for. Don't stop till you get one. And
I'm always available for offline chats.