re: David Marjanovic

[david peters <davidrpeters@earthlink.net>]

In response to my early query:

> In the meantime, if anyone can send me a pdf
> [or better yet, I hi-rez jpeg], I'd appreciate it, just in case I run
> into some red tape.

David Marjanovic, evidently in bad mood wrote:

>>>>Very unlikely, because the picture in the pdf has very low resolution (as,
grrr, usual for Nature). There even is no way to see the papillar surface
ornamentation on the eggshell fragment that is mentioned in the text and
indicated in the close-up photo!!!

Easy David. I was thinking a pre-publication photo had to be floating around. 
And besides, you would be stunned what the pdf does reveal.



DP > 1. the embryo is ossified

DM >>>>>I hope so.

This would imply post-independent or adult status. I know that in all other 
verts embryos develop bone tissue and I was raised and educated on the notion 
that the same would hold true to pterosaurs. This follows the observation of 40 
examples, so I can only follow and report the data. 


DP > 4. the sclerotic ring appears to be relatively large in relation to the
> skull length

DM >>>>>It must be -- except if the adults had _dramatically_ better vision 
than the
babies. Eyes have strong negative allometry; small animals have
proportionally bigger eyes than large ones.

This suggests we consider taxa that have, as adults, proportionately large eyes.



DP > 5. if the embryo is a baby Haopterus, the rostrum is much shorter and
> rounder than the neonate Haopterus I found [see pterosaurinfo.com]

DM >>>>It must be -- the brain has strong negative allometry, too. It gets 
totally
bloated very early in ontogeny and then grows very slowly. I'm sure you've
seen drawings or photos of _any_ vertebrate embryo!

Again, I was raised and educated to consider all the  tiny forms with a short 
rostrum and big eyes as juveniles. I was surprised as anyone to discover that 
pterosaurs were somewhat different.



DP > In addition, the record of Wang and Zhou is not good with regard to
> identifying pterosaurs and parts of pterosaurs.

DP >>>>. Ad hominem argument. Pseudoscientific.

A track record is a track record. Knowing beforehand that Wang and Zhou appear 
to have less of an interest in pterosaurs than in birds suggests that mistakes 
may be present here as well. What surprises me is your and others faith-based 
approach to this problem. You read the text and accept it as gospel. Be a 
scientist. _Test the hypothesis_. That's why Wang and Zhou put it out there.  

DP > I have a working hypothesis that indicates
> the Chinese embryo may not be an embryo at all,

DM >>>Then what is it doing inside an egg?

This recalls a famous line from Groucho Marx, "How he got into my pajamas, I'll 
never know." 
In this case I can see two possibilities. You'll hear within a few weeks.


> VIVIPARITY AND MATERNAL CARE IN PTEROSAURS AND OTHER HIGHER
> PROLACERTIFORMS

"Say never higher or lower"
-- Charles Darwin, written on the margin of a book
:-)

DP > Recent research has found

DM  >>>> It's not good to imply that 5 or 10 researchers all over the world have
found them when this isn't the case. Why not "I have recently found"?

No one is implying 5 or 10 anything. 



> these unossified offspring

Are you aware what this means? That they were all terminally rachitic, and
_suffering_ from it. Unable to support their own weight. Much like a
stranded whale.

You're making up this malady like a 17th century Puritan. 
The evidence says that most baby pterosaurs were just fine.



DP > In <i>Cosesaurus</i> a ruptured sac is visible within the mother's torso,

DM >>>> If such a thing is preserved, then where are all the inner organs? Why
doesn't it _at least_ look like *Scipionyx*?

Why don't you look at the specimen? Maybe I missed something beneath all that 
gastralia. If a jellyfish was preserved on the same slab, surely a liver and 
some kidneys should be prominent.



DP > a half-size juvenile

DM >>>> An unossified juvenile half the size of an adult? What have I 
misunderstood
here?

You'll see it (or you won't) at pterosaurinfo.com. It falls within the typical 
pterosaur pattern of development.



DP > Relatively short snouts and large orbits place these tiny adults close
> to <i>Scaphognathus</i> and <i>Dorygnathus</i> in cladistic analysis.

DM >>>>These features are classical features of juveniles, see above.


True, and as I said before, everyone was raised on this, including your truly. 
Perhaps that's why they were ignored in cladistic analysis. However, taking the 
chance that something might be learned, I inserted a number of these tiny 
pteros into the matrix and came up with new perspectives on pterosaur phylogeny 
(see pterosaurinfo.com > taxa > family tree). As in pre-mammals > early 
mammals, a size squeeze facilitated the development of pterodactyloid-grade 
characters in four lineages of pterosaurs. Again, and before you get all huffy 
about having your dogma shaken, I urge you to approach this like a scientist, 
instead of a priest of the Inquisition. Gather the data, create the matrix, see 
what shakes out. "The times they are a changin'."


DP > Pterosaur offspring do not have proportionately larger eyes.

DM >>> See above for why this is _funky_.

See above. This too comes from observation. Not a notion of what "should" be.



DP > The rostrum may be shorter.

DM >>>>> I hope so.

"May" means not always here.




DP > At birth the wing finger may
> be relatively longer than that of the parent

DM >>> While the animal is unable to fly???

See my article in Prehistoric Times for a take on this (pterosaurinfo.com > 
news)


DP  > The data shows that no
> more than two juveniles and two embryos are present, except in breeding
> grounds where the matrix may be littered with abandoned babies.

DM >>>>Why "abandonded"?

Sadly, some offspring, for whatever reason, were unable to hitch a ride on 
their mother. Left behind as she flew off from the breeding ground/rookery, 
they died. Natural selection at its best.

DP > As in bats, offspring clung to the mother, apparently beneath
> her and oriented posteriorly.

DM >>>>> Not obvious from those of your tracings that I've seen.

Rarely are the juveniles actually attached to their mothers insitu. I've seen 
it in Zhejiangopterus and Rhamphorhynchus. Since writing this, however, the 
tall crested nycto baby showed up. In this case a back rider would seem better 
for runway clearance. Once airborne, however, any position would do.



DP > Delayed ossification facilitated the
> development of extremely thin-walled hollow bones.

DM >>>>>>No, the development of severe rachitis. Pneumatic bones are formed by 
air
sacs _destroying present bone_, not by bone growing as a tube.

I'm guessing that the long bones of baby pterosaurs already have air sacs in 
place, and that what we are seeing, as in the adults, are collapsed tubes. 

I'm glad you're this interested in pteros, David. And a good challenge is 
better than coffee in the morning. 

David  Peters
St. Louis