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re: If No. 9 is a hatchling



responding to David Marjonovic's replies:

dp:
> I wonder what size the mother would have to be if No. 9 was indeed a
hatchling?

dm:
Well, if the meanwhile conventional wisdom is right and *Pterodactylus* &
*Germanodactylus* had a wingspan of some 2.5 m when they were adult (like
*Pterodactylus longicollum*), then I don't see any problem.

.........Well, you skipped all the candidates that are phylogenetically closer. 
And, forgive me if I'm mistaken, but if you're into conventional wisdom and you 
consider P. longicollum the adult, then the little pterodactylids to their 
phylogenetic left, some about the same size as No. 9, are they all hatchlings 
and juveniles? If so, why do they have extra-long rostra and small eyes like 
adults do? Something is illogical here. I would expect a gradual trend via 
ontogeny. Not a big leap in 'week two' of their young lives.

Speaking of paedomorphosis, there are dogs with shorter rostra that are adults. 
They have shorter rostra than their ancestors. Monkeys have shorter rostra than 
lemurs. There are people who look like children but are adults. They have 
shorter rostra. You can't be sure a short rostrum is a juvenile character, 
especially if the phylogenetic ancestors, in this case the scaphognathids, also 
had short rostra. No. 9 just looks like its grandparents. That's all.

The key is this: evolution works one part at a time. If you're an 
australopithecine first you get a human pelvis, then feet. Then you get a human 
brain. Finally, way late, the chin pops on. (I'm not saying this for you, 
David. You know this stuff. Web surfers may not.) In scaphognathids the skull 
stayed pretty much the same in the next phylogenetic step (No. 9), but the 
already diminishing tail diminished further. The proportions of the 
antebrachium and metacarpus became more equalized. The feet stayed the same, 
but digit V was less ossified  because its so small (but it's still there). 
That's about it. That's not a lot to get to No. 9. It takes more steps to get 
to the long-snouted, long necked, pterodactylids with all their other skull 
modifications.

The trouble is, none of the literature has ever pointed to a good 
rhamph/pterodac transition. It's always been a big jump to go from R. muensteri 
to P. kochi or Ornithocheirus or you name it. That's old thinking. Now that 
problem has been worked out. The transitions from protorosaur to pterosaur and 
from 'rhamphorhynchoid' to 'pterodactyloid' are as smooth and gradual as in 
synapsids to mammals. And this is one of those transitions. 

Think of it: how do you get a pterodactyloid from a rhamph? 

A relatively shorter weaker tail? That's a juvenile character retained in the 
adult.
A relatively shorter antebrachium versus the metacarpus? That's a juvenile 
character retained in the adult.
A relatively longer skull relative to the torso? That's a juvenile character 
retained in the adult.
A relatively smaller naris relative to the skull? That's a juvenile character 
retained in the adult.
Relatively big eyes compared to the rostrum? Well, pterodactylids aren't really 
known for their big eyes. Maybe those were retained.

It starts with hormones and ends up with genes.

If the first two pterosaurs ever discovered were Scaphognathus and No. 9, then 
the story would be different. You'd see the similarities. Right now you see 
only the differences because of the books you've read. Stop splitting and start 
blending. 

David, I sent you the files you'll need to see the complete picture. I'm here 
for you. 

dp:
> Your challenge is to match a baby with a mother.

dm:
Nope. The fossil record is way patchy enough to spare us this challenge.

>>>>>>>
Hey, you're backing away. Listen, just find a good sister taxon. I won't be a 
stickler for every skeletal detail. But I will insist that the baby, give or 
take 20%, fit through the cloaca of the mother you choose.  That's all you have 
to do.

If you can't find a match, you're left with the next most parsimonious answer: 
They're different enough to merit separate taxa. 

Don't back down and end up agreeing with me. Find me a real baby!

Hope to hear from you, or anyone else who wants to accept the challenge. 

David Peters