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pterosaur stuff



Just got back on the list from a multi-week absence, putting the final fixes on 
the interrelations of protorosaurs including pterosaurs. Now that that 
multi-year project is behind me (...or is it...?) hopefully I can become more 
active in other tasks and passtimes.

Thanks to both the 'pros' and 'cons' on the nomenclature and egg questions. 
Didn't mean to cause trouble. Just to raise a red flag. Hopefully all of this 
discussion will add clarity to something which was 'set in stone' by Nature, 
but didn't add up when put to the test. All I can say is, I calls'em as I 
sees'em. 

To anyone who thinks the embryo is a genuine ornithocheirid embryo, I would 
like to challenge you to make the reconstruction and send it over. Use the 
figures in Nature. Or trace whatever you can grab at whatever resolution you 
cand find. Just test it. If it's really an embryo in an egg, and a derived 
ornithocheirid at that, I'll be the first to pat your back and shake your hand. 
That way I can forget about all the ephemeral stuff I've been spotting. I think 
you'll find, as I did when I rebuilt Wang and Zhou's tracing, that what you get 
couldn't possibly be an ornithocheirid. Too many characters don't fit the 
pattern, starting with not a short 'mandible', but a ridiculously short 
'mandible.'

A few quick points:

Sometime in the next few weeks, somewhere in Denver, someone will show you a 
slide of a tiny pterosaur and tell you that it is a juvenile or a recent 
hatchling. It will have a short snout and big eyes. It will have short wings 
and not much of a tail. At this point I draw your attention to:

www.pterosaurinfo.com/scapho_clade.html

Here you'll find a scaled graphic depiction of what PAUP found in one clade of 
pterosaurs derived from a sister taxon to Scaphognathus crassirostris. You'll 
note two lineages, both taking the first step with reduced variations of 
Scaphognathus, the so-called 'juvenile' specimens. Following those you'll find 
even smaller pterosaurs, some of the smallest pterosaurs known, including that 
Denver juvenile with the short snout and big eyes. Hopefully you'll see that 
the larger ancestral taxa to their left also have a short snout and big eyes. 
Their wings are short and their tails are diminishing. This looks like a 
phylogenetic sequence to me. And if you don't like the drawings or think they 
are misleading, I urge you to test them with scaled tracings of your own. 

By the way, I've drawn only fully ossified specimens here, recognized by 
Wellnhofer (1970) and featured in a number of European museums. No ephemeral 
juveniles have been snuck in here.

Now, take a breath and see what follows the tiny pterosaurs. In one lineage, a 
small-to mid-sized ornithocheirid and cycnorhamphid show up, according to PAUP. 
Still, it's a pretty big size jump. Look for missing taxa to fill this gap 
someday, hopefully soon. I already know of one small to medium cycnorhamphid, 
so they're out there.

In the other lineage, a more familiar phylogenetic growth pattern through a 
stepped series of ever slightly larger pterodactylids can be seen. The 
interesting thing is from No. 9 -- which everyone but me thinks is a hatchling 
-- to No. 12 and AMNH 1942, the pterosaur gets taller, but the torso remains 
the same size. Sounds more like evolution, which works on one or two parts at a 
time, rather than ontogeny, which packs on the ounces and pounds in a more 
widespread fashion, give or take during the awkward adolescence period.

The point is: size squeezes do occur and they happen alot in pterosaurs. Those 
tiny pterosaurs are adults, so it's no big surprise that they are found far 
from land, alone, fully ossified and fully fledged (provided with adequate 
wings in this case). 

Point two: Take a closer look at the phalangeal patterns, the pelves, the 
palates, the tooth arcades of these tiny pterosaurs and you'll see that they 
don't look like miniature versions of anything we know from the fossil record. 
They are unique. Sure they share characters with other pterosaurs both up and 
down the line, but as a total package you'll never find a match, even taking 
into account allometric growth possibilities. 

Anyway, raise your hand and object when this happens. Because now you have an 
alternate explanation. 

Part of supporting my own hypothesis is shaking down the competition. ... and 
that's o-kay.

We'll figure it out someday. ;  )

More later,
David Peters