Re: Coelophysis *feathers*???

["Waylon Rowley" <hot__male60@hotmail.com>]

To: Rob Gay


> Personally, I feel that feathers are probably a very basal characteristic 
> of theropods (I'll explain further down here). _Tyrannosaurus_ is well 
> within the group conisdered to have feathers, as judged by phyogenic 
> bracketing. But _T. rex_ shows no sign of feathers. But, it's more than 
> likely that _Tyrannosaurus_ infants had feathers for isulation, that were 
> later shed as the animal grew.

Well, last I heard we only have preserved skin from the base of a tail and 
under the throat for Tyrannosaurids. Birds have scutes AND scales, so I see 
no reason why a tyrannosaurid might have a rim of feathers along its back, 
or display feathers on its snout (rugose nasals? hmmmm....)

> But lets look at the other evidence. _Sinosauropteryx_ is early K, right 
> (this is a guess, I don't remember exactly)?

Yeah, 120 mya (approx.)

> Well, this is great, and I'm glad we have furry dinos, and I'm also >glad 
> that these primitive structures give us some insight into the >origin of 
> feathers. But, as long as this animal comes after >Archeopteryx, then it 
> doesn't show when feathers evolved. Furthermore, >if one accepts the 
> dinosaurian origin of birds and accepts that >Protoavis is in fact a bird, 
> then you almost have to have fully >developed flight feathers in the 
> Triassic. This would lead me to >believe that "feathers", in a rough sense, 
> are basal to theropods, >perhaps even being expressed as early as 
> _Eoraptor_ or _Herrerasaurus_.

Are you suggesting that C. longipes is derived from bird stock? As someone 
else on the list said, the animal's position in time does not matter, only 
its phylogenetic position is what counts. I have my doubts about Protoavis 
(e.g. its coelophysoid nature), so I don't know whether it's a bird or not 
(most likely NOT). We have scutes (pebbly ones like on the sides of crocs) 
in ornithischians, osteoderms in the sauropoda, and as I mentioned earlier 
in both C. sastrei and C. nasicornis (osteoderms and conical-scutes arranged 
in rows). This suggests that a full body of scutes are plesiomorphic for 
dinosauria as a whole, and since Eoraptor is a VERY basal member, I 
seriously doubt it was feathered. Besides, who likes fluffy monsters? :)
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