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Re: SAUROPOD FEATHERS



> archosaur@reptilis.net wrote:
>Fascinating; we have scale impressions from       >theropods, sauropods, 
>ceratopians and hadrosaurs. We >have "feather" impressions of only a few 
> theropods, all of which are maniraptors.

 
> True kind of.  We have skin impressions of theropods, sauropods and 
> ornithischians that exceeded 1000kg that show mosaic scales.  We have skin 
> impressions from only a few dinosaurs under 1000kg, most of them 
> coelurosaurs, all of them with dinofuzz or feathers.  

+++++++++++++++++++++

The Patagonian titanosaur embryos all show scale impressions (all the ones that 
are visible that is). They were the ones I was using as evidence for sauropod 
scales. I'm not sure we have any large sauropod scale impressions.

I do think it is pertinent to mention that only maniraptors have been found 
with fuzz. No other coelurosaurs have shown this. In fact, those that have had 
impressions found (i.e. the tyrannosaur impressions, and yeah, I know it's 
another big guy) have all shown scales. So, it would seem that maniraptora 
would be the starting point for this fuzz stuff, not coelurosauria.

______________________________

The only under 1000kg 
> non-theropod dinosaurs with skin impressions are Liaoning psittacosaurs which 
> are said to possess very long barbs and/or mosaic scales, neither of which 
> have been illustrated, so I cannot comment at this time.

+++++++++++++++++++++

I've seen the psittacosaur pictures and I'm not as confident as others are, 
that those barb things are even part of the specimen. They certainly don't look 
to be homologous wit the pterosaur or maniraptor fuzz.

*Sigh* that's probably all that should be said about these specimens until an 
actual paper is written on them.

Bloody waiting game!

______________________
 
*snip*

<<It reminds me of his video presentation at the AMNH near the _Oviraptor_ 
> skeleton, where he adamantly states that this _Oviraptor_ was proof positive 
> that birds were dinosaurs, because this animal died while sitting on its nest 
> like certain lizar..I mean birds do.>>
> 
> I am not sure what you're getting at here.  Are you suggesting that birds are 
> not derived thereopods?  Or are you simply stating that the brooding position 
> of Oviraptor, which is a behavioral trait, has a much larger phylogenetic 
> range?  I don't think that second [nor the first honestly] is going to have 
> much data supporting it.

+++++++++++++++++++++

No, I'm just stating that this wouldn't be the first time that Norell has made 
such an absolute statement based off of circumstantial evidence.

That "brooding" _Oviraptor_ looks more like an animal that was crushed while on 
top of its eggs, rather than one that was sitting there and incubating them. It 
very well could have just been protecting its eggs when the sandstorm/avalanche 
killed it. There are non-avian examples of animals that do this. As such, 
stating that the superficial position of this _Oviraptor_ is clear cut proof of 
dino-avian ancestry is really stretching it.

I don't doubt that birds are dinosaur descendants, but I do question a lot of 
the evidence for it; especially when it is not really anatomical.

_____________________

> <<So, has Norell *seen* the Patagonia sauropod embryos?
> .......
> That, and the embryonic sauropods have preserved SCALE impressions.>>
> 
> Embryos have scale impressions?  I have always been somewhat skeptical of 
> this claim for quite a few reasons.  First of all, most of the scale 
> impressions appear outside of the nests, and are completely haphazard around 
> the nesting site.  These are most likely the impressions of adults walking 
> around the nesting grounds.  Secondly, almost all of the eggs are broken and 
> possibly trampled, and scale impressions within the nest could be those of 
> adults manipulating eggs, or older juveniles.  Maybe sauropods never had 
> dinofuzz on their legs?

+++++++++++++++++++++

As HP Adam Edels already stated, these embryos are so well preserved that one 
really can see the scale impressions inside them. 

When it was first announced there were quite a few pictures accompanying the 
news story. One of them does show these impressions.

Unfortunately CNN, Reuters and all the other popular dino news areas, don't 
seem to have very good archives. I can't seem to find the story anymore.

I did find this AMNH link though:

http://www.amnh.org/exhibitions/expeditions/dinosaur/patagonia/

That shows some pretty good views of the skin on the embryos (since they were 
about to hatch, perhaps embryos is a bit misleading).

I'm guessing, much like HP Ronald Orenstein, that Norell is basing his 
statement off the possible homology between the pterosaur fuzz and the dino 
fuzz that was suggested recently.

This actually leads into an interesting parsimony question.

Is it more parsimonious to assume that this fuzz evolved convergently between 
pterosaurs and maniraptorans, or is it more parsimonious to assume that it was 
subsequently lost in the majority of dinosaur species?

Okay, so when I put it that way, it seems pretty obvious which one appears to 
be the "simpler explanation." I suppose it also depends on how "hard" these 
structures would be to evolve (again, assuming homology).

Has anyone done any comparative studies on the pile of moths, bees & 
tarantulas? Fuzz honestly, doesn't appear to be all that hard to evolve, but I 
could be wrong.

Jura

Oh and an addendum to my original post on this. The researcher's name is Zou, 
not Zoui.



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