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Re: If No. 9 is a hatchling



> combinging Nick's, Jaime's and David's juvenile characters:
>
> 1. large head - Large skull relative to trunk, limb, tail, etc., dimensions

> 2. large eyes - Large orbits relative to volume or area of cranium

> 3. shortened muzzle - Short snouts relative to cranium volume

> 4,  immature bone texture

     5. short limbs and tail relative to trunk length
     5. Extremities prolongated or extended relative to trunk dimensions]

  6. Manus and pes large relative to more proximal segments or limb girdle
     elements.

  7. Relatively short tail to trunk length

   Then adding:

    8. Juvenile teeth (perhaps with replacements nudging them out).

`   9. Unfused long bone epiphyses

    10. Unfused skull sutures

Okay, given that I'm an alien and I find an adult house cat and little tiger
skeleton. I've been asked to "Please tell us why we should assume that the tiger
cub is a neotenic adult
rather than a juvenile of a species related to but larger than a house cat."

What you've asked me to do, I cannot do. With everything I see in the tiger cub,
I can tell, because aliens read Romer 1971, that the tiger is a juvenile. And
here's how it relates back to No. 9.

Scale the baby tiger to the size of a house cat and I note that:

1. the tiger baby has  proportionately larger head. In No. 9 the head is 
slightly
shorter than the trunk, exactly as in the smaller Scaphognathus, SMNS 59395.  So
perhaps, No. 9 is not a juvenile.

2. Not sure about the relative orbit size in house cats vs. tiger cubs. In No. 9
the orbit is relatively the same size as in 59395.

3. the muzzle proportions might be about the same in house cat and the adult
tiger. In No. 9 muzzle proportions are identical to 59395.

4. immature bone texture. I imagine the tiger cub gets this one. Not sure if
anyone has ever noted the bone texture in in No. 9 and compared it to 59395.
Let's leave that one up for grabs.

5. Depending on the age (a few weeks old, short legs, a few more weeks, long
gangly legs) in a baby tiger, if they're like my 13 week-old puppy. Regardless,
No 9 has the exact proportions of 59395 in the hind limbs. Forelimbs are
different though. The limb as a whole is similar in length. It still just barely
touches the substrate when standing bipedally, but the metacarpals have 
elongated
and the antebrachium has reduced. That makes it a different genus.

6. The tiger baby would have larger manus and pes relative to the adult cat,
hands down. In No. 9 the manus and pes are identical relative to the torso in
59395.

7. I don't see much proportional difference in tiger vs cat tails. In No 9 the
tail appears to be reduced. It is certainly not as stiff as in 59395. I note,
however, that in both cases the tail is within 10% of the occiput-vent length.
But then, they are different genera.

8. Juvenile teeth, Easily seen in the tiger skeleton. Not really applicable to
No. 9, but the tooth count is similar to 59395.

9 and 10. Unfused long bone epiphyses and open skull sutures are easily seen in
the tiger skeleton. In No. 9 I don't see any difference in the tarsals, the
pectoral girdle or skull sutures relative to 59395. About the same.

Okay, so I didn't relate No. 9 to the pterodactyloids that succeed it
phylogenetically. Did I have to to prove my point? No. 9 is a little
Scaphognathid! And so are pterodactyloids! They're all related sequentially.

Write soon,
David Peters
St. Louis