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Re: Avgodectes



----- Original Message -----
From: "David Peters" <davidrpeters@earthlink.net>
Sent: Tuesday, July 26, 2005 11:58 AM

A recent submission involving virtually every known pterosaur in the
world got nixed. Some don't want me to include tiny pterosaurs in the
matrix (not sure what the size cut-off would be).

There isn't a size cutoff. There's a maturity cutoff. Firstly, there's no point in including both juveniles and adults of potentially the same species in an analysis, because they will likely not show up as sistergroups due to the fact that many apomorphies appear only at some time between hatching and maturity; secondly it's potentially misleading to include species known only from juveniles because they will likely appear in a too basal position, for the same reason as above. In short, do include all tiny pterosaurs in your matrix -- after you've shown that they are really adult.


Others need me to
visit every taxon (this is common practice in matrices of 7 to 25
suprageneric taxa, hasn't been done in matrices over that)

Of course it has been done. I happen to know the example of HP Oliver Rauhut's really big* theropod matrix in his dissertation.


* Yeah, OK, not when compared to the matrix of Holtz et al. in D2... 638 characters... <headache>

and get confirmation from others
(which I requested in 2002 without response).

What do they mean?

It's funny, how at one time everyone was shaking their finger saying
'without a cladogram there is no evidence' but when a cladogram is
supplied that reflects past work ? and only departs dogma with the
addition of taxa (see Müller 2004 to see how important taxon
selection/addition is) then feathers start to fly.

Adding taxa can be botched up. See above for the need to be careful with assessing maturity; see my misery for the great benefits of personally examining fossils that are poorly described and illustrated, not to mention the fact (mentioned several times on this list, years ago) that published data matrices often contain typos and must therefore not be simply copied; see theoretical studies and my experience for the need to add characters when you add taxa (...and even when you don't add taxa).


I don't see why such papers aren't allowed to be published. One can
always ignore or trash them later.

It seems to be a question of time and money. The Journal of Vertebrate Paleontology could easily appear monthly, I hear, if only there were enough money to do it; there's no shortage of submissions.


PS: Still looking for:

1. Evidence of a deep chord wing on a pterosaur

Can't help you here.

2. Evidence that baby pterosaurs were cute (short rostra, big eyes) and
that they morphed into adults.

Brain and eyes are negatively allometric, means, their relative sizes depend on (among other things) absolute body size. This is why these relative sizes are ontogeny-related. At the time the brain of a vertebrate embryo forms, it is easily 1/3 total body size. So it is the normal state of affairs -- the plesiomorphic state -- for vertebrates to be cute as babies, and in the absence of impressive evidence to the contrary, we should preassume it for pterosaurs. Occasionally some special adaptations produce departures from this pattern, though. As an example of an exception to another normal ontogeny pathway, horses are born with relatively longer legs than their parents have; this way they can keep up with the migration of the herd. I remember something about young tyrannosaurs having long snouts for hunting on their own... So pterosaurs hatching with un-cute faces is not impossible. But it's a relatively extraordinary claim, and as such it requires relatively extraordinary evidence (such as an un-cute pterosaur with poorly ossified carpals/tarsals/small phalanges, poorly ossified joint ends of long bones, open neurocentral sutures, and immature bone texture or perhaps a thin section of a bone that shows it was in the phase of juvenile fast growth).


3. Evidence of what basal plantigrade pteros did with that dang big
lateral toe while walking (see keyword: 'sauria aberrante' for the alt.
explanation).

It looks (er... literally) like it was involved in the "hindwing". But I wouldn't bet money on that.


4. Evidence that pterosaurs were related to dinosaurs, or any archosaur.

Several published cladistic analyses, plus reportedly a big unpublished diapsid analysis (lots of taxa, including "prolacertiforms") by Senter. -- Of course evidence is not proof. You (will) have a chance to falsify them all, if your analysis will be better than them all. I dimly remember your lists of synapomorphies of pterosaurs with *Longisquama*, *Cosesaurus*, *Macrocnemus*, *Tanystropheus* and so on on your old website, and all in all they looked pretty convincing, while the published lists of synapomorphies of Ornithodira and Pterosauromorpha are short and sort of bizarre, so please understand that I'm not being rhetorical here.


Sorry for the impolite question, I'm too tired to think in terms of social intelligence -- have you found out how to order multistate characters in a NEXUS file? When I saw your pterosaur matrix -- long ago! -- you had several characters that were morphological series, yet all your 183 or so characters were unordered and thus _had to_ produce _bogus_ results. I have asked you a few times since, and I can't remember an answer. Needless to say, I'd gladly explain how to do it.

5. Evidence that Avgodecetes was an ornithocheirid

As I don't know an ornithocheirid when I see one, I can't help you... all I can say is that your interpretation of the fossil doesn't look convincing...