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Re: Hanson 2006, Mortimer, Baeker response


On Jun 12, 2006, at 6:58 AM, Martin Baeker wrote:



Hmm - *my* copy of "The Dinosauria" has lots of unresolved branches in
the cladograms - don't see that any of those is anywhere near being
perfect. Yes, there are no strange lineages, but if we look at a
cladogram comprising as many species as your probably does, the number
of unresolved points is huge.


Unresolved points, by definition, raise the number of trees above "1". So, you speculate in error. The number of unresolved points is zero.


Again, the argument is circular: To prove that your 1-MPT-cladogram is
correct and that the fossil record is complete enough, you use the
fact that you have a 1-MPT-cladogram.

Remember, Martin, no one promoting any cladogram promotes that it 'proves' anything. So, ease off and remember we're in hypothesis land. Currently my cladogram solves more problems, includes more taxa and characters and answers more questions than any other cladogram out there. Just because you don't like the answers due to your prior education, doesn't mean they're not valid.


Yes, I *hope* I am - everybody should be suspicious of a theory that
fits all facts perfectly.

Wow. I didn't think you'd play that card. That tells me alot about you. So, 2 + 2 only seems to equal 4?

Not that it is impossible, but too many
times in the past those all-explaining theories were just wrong.


Too many times? Can you name two times?

Ending with a 1-MPT cladogram does *not* prove you right, no matter
how nice it looks. (It does not prove you wrong, either.)

Thank you for that. Again, proof is impossible in a cladogram. It's not the goal.



Afraid of the danger of fooling yourself by a nice-looking outcome.
(And yes, I do some refereeing, if not in the paleo field. So far
didn't realise that referee is to be translated as "block-headed
conservative know-it-all" - don't worry, no offense taken, I had
enough papers rejected myself to understand bad feelings towards
referees.)

Your words, not mine, but I think you understand that in lieu of facts and errors, referees sometimes use phrases like, "this seems dangerous." To me it only seems dangerous because it rocks a boat that needs to keel over. 



A cladogram in itself is, as far as I understand it, not yet a
hypothesis (Cladogurus on the list, please correct me). It is an
ordering of entities (species or specimens) based on similarity
criteria (character states). *If* you assume, in addition, parsimony
and (more important to this discussion) that all entities you put in
*are on the same footing* (i.e., they *only differ wrt their
phylogenetic position*), only *then* does it become a hypothesis on
phylogeny. If this additional assumption is wrong (for instance,
because you added entities that are not on the same footing, like
adults and juvies), your phylogeny will probably also be wrong.

Thank you for inserting the word 'probably' which always allows for another possibility. 


But let's take the opposite stance.

Let's say that No. 9 is a juvenile. What is it a juvenile form of? Be specific
and show evidence that it is indeed the candidate you propose and that it
doesn't have more evidence (remember parsimony) that it is closer to my
candidate. 

And I cannot claim that the adult form has not been found because the
fossil record is complete? Circularity again?

No, you're backing away from an argument. If No. 9 is a juvenile, as others say, it needs to be identified as a juvenile of something, even within a broader category or clade. So, the 'parent' of No. 9, if it exists, does not need to be the biological parent, but just some uncle or aunt you can point to that is more similar than the taxon I point to (as determined from phylogenetic analysis). Don't back off, if you know your pteros, give me _any_ adult/juvenile pairing. And by the way, back to the baby monkey/baby human argument, if baby pteros are more similar to each other than they are to adults, then why do they appear in various separate places in my cladogram? The monkey/human/salamander argument can be falsified in many ways. 

But to find out whether it is a juvenile or not, you cannot look at
cladograms - look at the proposed juvenile's bones and check whether
they are fully ossified, remodeled, whether sutures have closed etc.

I have and they're adult-like. But with neotony, and considering their absolute size, is it impossible for tiny pteros to have shorter lifespans and to be having sex and laying eggs prior to complete ossificiation? I'll not bring up humans here, because we all know that story. 



I would (frequently, not always) expect embryos (and juveniles) to
look like more basic members of the clade than their parents do. But
there's lots of things to change that, like paedomorphosis or special
selective pressure (foals have relatively longer legs than grown
horses). In addition, I would expect relatively larger brains and eyes
(but that goes for small adults as well and thus does not help much,
although it might if eyes are relatively huge).

Expectations are a priori assumptions. Better to follow observations. 

But it was *your* argument stating that these tiny pteros would fit
because there are tiny birds nowadays, so this is something beyond a
cladogram. And this argument I reject - just because nowadays (with
mammals and birds) niche-partitioning is done species-wise doesn't
mean it was so always.

In many batches of offspring, some are larger and some are smaller than others. Natural selection works its wonders, sometimes in a series of size squeezes or size balloonings, which is exactly what I see in the cladogram. A series of gradual increases and decreases.

Sorry, I don't understand this argument. How does it relate to the
problems an adult, warmblooded pterosaur of minuscle size would have
regulating its temperature (and it would be much worse off than the
shrew because of its heat radiators, aka wings)? Again, this argument is
*not* about cladograms, it is about whether these teeny-tiny adult
pterosaurs are plausible enough to be entered into a cladogram.

Such biological questions have not been answered yet. Only hypotheses have been advanced. The 'hows' and 'whys' I leave to you. I'm only concerned with the 'what' and 'who' questions in this study.

David