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Re: David Marjanovic's ptero comments
All of your suggestions require your theories to be correct and the
babies you see to be real. I think that "like a good scientist" you
should consider the possibilities that you are incorrect in assuming
that you are seeing babies, embryos and dorsal frills on these slabs.
Science requires a person to be able to say they were wrong and that
their theory was falsified. Theories are constantly being verified or
falsified in science, in fact, science works off trying to falsify and
verify theories. In this case, your theories on pterosaur babies (all
pterosaurs were viviparous, all pterosaur braincases exhibited positive
allometry, etc.) were falsified and those of others (all pterosaurs were
oviparous) were verified by the discovery of a pterosaur egg and embryo.
It is just the way sciece works and every scientict must be able to
accept both success and failure, or being correct or being false.
DP > 1. the embryo is ossified
DM >>>>>I hope so.
This would imply post-independent or adult status in the radical hypothesis. 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. The new hypothesis follows the observation of 40 examples, so I can only follow and report the data. Although not a scientist, I play one on the DML.
This requires all your pterosaur babies to be real, not just
discolorations and matrix features. I think that before looking for
babies, one has to consider that ALL vertebrate embryos are ossified or
partially ossified. Only at very early stages are embryos completely
unossified. This egg shows a pterosaur embryo in its latest stage of
developement. All pterosaur babies would have to have had ossified bones
after birth, no matter wether pterosaurs were oviparous or viviparous.
DP > 4. the sclerotic ring appears to be relatively large in relation to theOnce again, this requires your babies to be real. First, before going
any further with claims of discovering babies one has to ask the
question "why woud pterosaurs be any different from ALL other
verterbrates?" If they differ from all other vertebrates in such ways,
they are probably are not real.
DM >>>>>It must be -- except if the adults had _dramatically_ better vision
babies. Eyes have strong negative allometry; small animals have
proportionally bigger eyes than large ones.
This suggested that we consider taxa that have, as adults, proportionately large eyes, while still not rejecting the possibility that this is an embryo.
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
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 from the norm.
They shouldn't be! There are reasons that the brain shows such strong
negative allometry. Largely because most brain cells are unable to
reproduce and therefore the brain cannot grow in size. This negative
allometry is yet another feature that all other vertebrates have and
pterosaurs simply can't be any different considering the fact that brain
cells work the same way in all vertebrates known.
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. I, like other scientists, try to keep the "I" out of it.
Nobody but you has been able to even see these pterosaur babies!
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. For the moment, though, the subject is reproduction.
First of all, I'd expect this sac, if it were an egg and Cosesaurus was
oviviparous to have a different color from the stone, however, it
doesn't seem that way, so I'd consider it all just artifacts of
preservation and preparation, probably just features in the matrix that
are the result of the sedement and the specimen's taphonomy.I looks
nothing like Scipionyx to me either.
DP > a half-size juvenile
DM >>>> An unossified juvenile half the size of an adult? What have I
You'll see it (or you won't) at pterosaurinfo.com. It falls within the typical pterosaur pattern of development.
And believe me, this one _is_ invisible. Only revealed through undirected tracing.
Yet again, I'm not of the opinion that it is even real.
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 the wee ones 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 appears to have 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'." It took me a few years of head scratching to come up with this.
But I offer it to you freely.
DP > Pterosaur offspring do not have proportionately larger eyes.
DM >>> See above for why this is _funky_.
Also see above. This too comes from observation â€“â€“ not a politicized notion of what
DP > The rostrum may be shorter.
DM >>>>> I hope so.
"May" means not always here.
As I said, this requires all your babies to be real, and I do not
believe they are. It also means that pterosaurs are an extremely strange
bunch of vertebrates whose growth and development patterns seem to go
against those of all other vertebrates.
<JOKE>Maybe they aren't really vertebrates, but alien life forms
introduced to Earth by an alien race who feared their becoming extinct.
It does explain their oddly sudden appearance during the late
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). No one knows why. It's just an hypothesis.
Again, it requires these babies to be real.
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.
In bats the young cling to their mothers because they need the mother's
milk and warmth since they are born naked, since it was very unlikely
that pterosaurs produced milk, and pterosaur young most likely were born
with "pterofuzz" I do not see why this behavior would develop in the
DP > Delayed ossification facilitated the
development of extremely thin-walled hollow bones.
DM >>>>>>No, the development of severe rachitis. Pneumatic bones are formed
sacs _destroying present bone_, not by bone growing as a tube.
I'm guessing that the long bones of baby pterosaurs already had air sacs in place, and that what we are seeing, as in the adults, are collapsed tubes.
I think Dave practically took the words out of my mouth in his latest reply.
a good challenge is better than coffee in the morning.
Eh, I'm a tea drinker.
The Pterosauria: http://www.archosauria.org/pterosauria/
Dinosauricon Art Gallery: http://dino.lm.com/artists/display.php?name=mike