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Re: Carniadactylus paper and pterosaur ontogeny
On Aug 1, 2009, at 5:47 AM, David Marjanovic wrote:
DP: Unfortunately Fabio did not test MPUM 6009 as a separate taxon to
see if it would indeed nest with the former E. rosenfeldii.
DM: This would require scoring all ontogeny-related characters
as unknown for MPUM 6009. How many would that leave?
You may be a little behind the times, David. Pterosaurs and their
nonvolant sisters experienced isometric growth. If two taxa are the
same species, no matter their ontogenetic age, they would nest as
sisters. If MPUM 6009 nests elsewhere, closer to another taxon, it is
not a sister. So, contra tradition, there are NO ontogeny-related
This is just nonsense. Isometric growth has been demonstrated for
the forelimb-hindlimb ratio -- and that's it. Skulls most obviously
didn't grow isometrically in pterosaurs; neither do they anywhere
You're standing by an unproven paradigm. Show me one juvenile and one
associated adult to prove your statement.
All prior assumptions were just that, assumptions. That
includes tooth count, orbit/rostrum ratios, tiny pedal phalanx
ossification, scapulocoracoid fusion, sacral fusion, etc.
Every embryo now known, plus the baby Pteranodon (see below).
Put them all into a cladogram and your eyes will pop.
Phylogenetics obeys the law of "garbage in, garbage out". If I put
actively misleading scores into a matrix, PAUP* will actively
Hey, try it. Put either a baby *Apateon gracilis* or a
postmetamorphic *Apateon gracilis* into a data matrix that contains
other temnospondyls and lissamphibians, and your eyes will pop.
Don't try to confuse the issue with other taxa. tsk. tsk. Pterosaurs
Maisano 2004 in JVP provides modern analogs.
Would surprise me. Could you give me the full reference? No Maisano
published in JVP in 2004 (SVP meeting abstract volume included).
Sorry, typo. Maisano JA. 2002. Terminal fusions of skeletal elements
as indicators of maturity in squamates. J Vert Paleo 22:268–275.
All the above is proven by adding embryo and hatchling Pterodaustro
to any cladogram that has Pterodaustro adults. You'll find they nest
That merely shows that *P.* has a large number of ontogeny-
independent autapomorphies that are present in these matrices. It
might be enough to put *P.* (adults and babies together) in some
wrong place in the tree.
Your guessing wrong. The hatchling and embryos of Pterodaustro don't
even have skull characters we can use.
Although, it is of considerable interest that the one
good complete skeleton of Pterodaustro (adult) has distinct pedal
phalanx and metatarsal proportions from the Pterodaustro hatchling.
Maybe NOT conspecific.
These are the very characters that I'd expect to vary with ontogeny.
Or at least with absolute body size -- there's little that still
works if you scale it up or down precisely.
The distinct patterns are not as you assume.
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.
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.
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.
An important conclusion of my recent work (with Michel Laurin: 2008,
Contributions to Zoology; 2009, Evolutionary Biology, online only so
far), already found by other people earlier to some extent (check
out fig. 10 of Warren 2007, JVP 27(4)!!!) is that not only do
mistakes in the matrix lead to mistakes in the trees, but they lead
to mistakes _of unpredictable kinds and magnitudes_ in the trees.
You can't, for example, say "if there are any mistakes left in my
matrix, they're tiny, insignificant ones that can only lead to tiny,
insignificant mistakes in the results" -- _that's not how it works_.
You're going off subject.
(Naturally I can send pdfs.)
On the influence of ontogeny, see our 2008 paper: we took a matrix
that found the lissamphibians as temnospondyls, changed _three
cells_ from known to unknown because we changed our interpretation
of the little temnospondyl *Doleserpeton* from adult to immature or
paedomorphic, and <poof> the lissamphibians came out as lepospondyls.
And various fish and insects change remarkably with ontogeny. But
pterosaurs don't. You must understand this by testing it on
pterosaurs, not pre-amniotes.
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.
BTW, Bennett from 1991 on notes the
bone texture issue appears on immature and mature
Pteranodon specimens of the same size.
Didn't he conclude neornithean-like determinate growth in
(I don't have the paper handy right now.) That's how it looks like
to me: in many birds, sexual maturity comes after growth ceases, so
you'd expect immature bone texture in some individuals the size of
adults because they've just finished growing and are only starting
to remodel their bones.
I have no problem with that. By my statement I wanted to note that no
matter the size, immature bone texture may appear, even on full size
pterosaurs no matter their overall size.