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FW: Feathered dinos





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> From: wdm1949@hotmail.com
> To: nekarius@hotmail.com; dinosaur@usc.edu
> Subject: RE: Feathered dinos
> Date: Sun, 8 Nov 2009 18:58:33 -0700
>
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>> Date: Sun=2C 8 Nov 2009 23:45:25 +0100
>> From: nekarius@hotmail.com
>> To: dinosaur@usc.edu
>> Subject: RE: Feathered dinos
>>
> Again. Don't correlate hair with feathers. Both are thermoregulatory. Fine.=
> But
> hair and feathers are so different structurally that if they thermoregulate=
> d the
> same way mammals would have developed them as well or a similar analog. 250=
> million
> years tells us ...... No.
> =20
>
>>
>> Well=2C it seems that some messages are truncated=2C don't know why (viru=
> s?). Anyway...
>>
>>> Michael Erickson wrote:
>>> So what I'm saying is that two specimens of _Compsognathus_=2C one with =
> probable dermal armor=2C another with definite caudal scales=2C and without=
> a single tiny trace of feathers between them is suggestive to me that feat=
> hers were either greatly reduced in distribution on the body of this taxon=
> =2C or were altogether absent (the former may be more likely). Then=2C of c=
> ourse=2C there's Juravenator=2C which has preserved on the matrix very tiny=
> =2C soft=2C and fine scales around the hind limbs and tail=2C but suspiciou=
> sly no feathers. Again=2C the scales are very small=2C fine=2C and soft=2C =
> only very slightly less so than feathers. Why were they preserved=2C while =
> the feathers=2C if they were present=2C were not?
>>
>> Actually=2C I believe we do not expect to find feathers in Compsognathida=
> e because they are the most basal clade of theropods with filamentous struc=
> tures (if we consider them to be more basal than Tyrannosauroidea). These s=
> tructure are "proto-proto-feathers". Having say that=2C as David Marjanovic=
> said=2C no skin is preserved at all in both 'Compsognathus' specimens and =
> we can therefore assume they could have had filamentous integuments as 'Sin=
> ornithosaurus' possessed.
>>
>>
>>> Dale Mcinnes wrote:
>>> Don't correlate feathers with fur.
>>> I'd be careful here since feathers and hair are radically different in t=
> heir structure. The loss of hair in mammals because of size does not necess=
> arily correlate well with the same supposed loss in fuzzy dinos. In fact th=
> e larger the bird the larger the feathers and the greater the covering. Eve=
> n small birds may possess large feathers. There is no discernable loss of t=
> hese structure s in extant birds because of the increase in size. I could e=
> ven see sauropods entirely draped in feathers. Maybe someday eh??
>>
>> Well=2C I correlate hairs with the filamentous integumentary structures f=
> ound in some basal coelurosaurs which I can also qualified as "poil" (=3Dha=
> ir) in French=2C even the structure is different from the 'true' hair in ma=
> mmals. That's why I used the word "fuzz" when referring to the deep appenda=
> ges found in many coelurosaurs ('Beipiaosaurus'=2C 'Sinornithosaurus'=2C 'D=
> ilong'=2C etc.) and 'Tianyulong'. Indeed=2C the structure of these filament=
> ous appendages found in dinosaurs are different with those found in mammals=
> (and pterosaurs=2C I believe)=2C I totally agree=2C but their utility is e=
> xactly the same: thermal insulation. Therefore=2C I think it is likely to i=
> magine that these filamentous structures were almost invisible in very big =
> dinosaurs=2C as it is the case in mammals.
>>
>> Second=2C I do not believe at all that feathers were present in other non=
> -theropod clades=2C even the latter could have had filamentous structures i=
> n some part of their body=2C along with the scaly skin. No need to say what=
> =2C it goes without saying.
>>
>>
>> Christophe Hendrickx
>> http://spinosauridae.fr.gd/
>>
>>
>>
>>
>>
>>
>>
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