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Re: Carniadactylus paper and pterosaur ontogeny




Besides, why would taphonomic association be oh so compelling evidence for conspecificity?

No one said anything about taphonomic association.

And aren't you the one here who's offering an extraordinary claim and therefore has to put some evidence on the table? Parsimony is against you so far.

The evidence is the embryos.


Sorry, typo. Maisano JA. 2002. Terminal fusions of skeletal elements
as indicators of maturity in squamates. J Vert Paleo 22:268–275.

Oh yeah, that one. Thanks for the ref.

You know, it really disappoints me that you bring it up again. Last time you did (years ago), several people pointed out that it goes _against_ you: by showing that several bone fusions so far thought to indicate maturity in squamates can actually occur considerably earlier, it shows that individuals can look _more_ adult than they are. It neither says that individuals can look _less_ adult than they are, nor does it mention proportions at all, it's only about, as the title says, "terminal fusions".

You, evidently, are not familiar with the tiny pterosaurs with etp, scapulocoracoid and sacral fusion. Nothing in Maisano 2002 goes against my hypothesis. If it does, please be more specific.




Who said all autapomorphies of *P.* have to lie in the skull?

No one. Wellnhofer used orbit and rostrum ratios. Bennett and Jouve used tooth count. Those lie hidden in the Pterodausro embryo. That's all I'm saying.



>> A privately-owned Pteranodon, 1/4 the size of P. marshi (skull)
>> and P.ingens (post-crania) has the proportions of an adult
>> including a fused extensor tendon process.
> So it doesn't have the same relative skull size as either adult *P.
> marshi* or adult *P. ingens*? Did I understand that right?
>
It has a long rostrum and tiny orbits, like the adults.

_Just_ like the adults? Could you quantify that?

Without a scale bar, you can't tell the difference.


>> Same goes for Bennett's "juvenile" Anurognathus. Unpublishable
>> because it is privately held but a pdf is available through me.
>
> I'm interested in that one.

Coming by separate post.


Thanks, I got it and have now read it. Unfortunately I can't test any of your bone identifications and reconstructions, because the photos are just abominable.

The specimen is very difficult to work with.

I can say, however, that if your reconstruction is right, this tiny specimen has the relatively _smallest_ eyes of any anurognathid.

Possibly. I'd have to see your frame of reference. And with the flattest skull, that's no surprise.

Either it was much more diurnal than the others, or the reconstruction is wrong (...as the S-shaped reconstructed lacrimal already suggests, frankly).

You need a straight lacrimal stem for some reason?

After all, all else being equal, relative eye size doesn't directly depend on ontogeny -- it depends on absolute body size.

All else is never equal. Ask any blind mole rat.


BTW, in the manuscript you talk about "the basipterygoid" as if it were a bone. That's confusing. Is that a misunderstanding on my part?

Possible typo. Thanks for the catch.

>> The only pterosaurs we KNOW that are NOT adults are those inside
>> eggshells. All other suspects need to be placed into a
>> phylogenetic context to test their nesting.
>>
> What I've been trying to get into your head for the last 5 years is
> that this does not work. PAUP* starts from the _assumption_ that
> all OTUs are in the same ontogenetic stage. If you violate that
> assumption, you introduce mistakes.
>
Stop. Look at the embryos. They are identical to adults and sister
taxa adults in all proportions. With isometric growth you CAN use
embryos in pterosaur analysis.

The last sentence does logically follow from the second-to-last... which, in turn, is unfortunately wrong.

Not sure we're going to get anywhere until you show me yours and I show you mine.

Tetrapods in general, even vertebrates in general, even in fact animals in general have a lot of patterns of development in common. You are saying that pterosaurs are utterly radically different -- you put the evidence on the table, not me.

The evidence is in every museum that has pterosaurs. Look especially at the feet. You'll find they're much like fingerprints or DNA markers in their varied metatarsal and phalangeal proportions.

> Long ago (probably in 2005) I sent you the "ontogeny
> discombobulates phylogeny" paper (Wiens, Bonett & Chippindale,
> Systematic Biology, 2005). Did you ever read it?
>
Yes. Not pertinent to isometric growth.

If isometric growth in fact existed, which it doesn't.

Reynoso 1998 thinks it does.


>=
Doesn't that make it irrelevant to more slowly growing animals, in which bone remodeling had plenty of time to keep up with growth?'

Not sure what you mean by slow growing and fast growing animals. In my research both Iguana and Corvus took about 2 years to reach full size.


By my statement I wanted to note that you need to look at the reasons for _why_ immature bone texture can appear on adult-sized *Pteranodon* -- because that quickly demonstrates that your generalization about all pterosaurs is invalid.

Let's just look for smaller versions of bigger pterosaurs. They're very hard to find, as you know.

We're in science here. We're not content with discovering laws, we want to come up with theories to explain them.

Let's get the facts straight first, starting with what pterosaurs are, phylogenetically.

Spirited discussion. Thanks for the bout.

Best,

David
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