[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Feathered dinos



 <SNT101-W606C2AAB0781DE19F7DE1CD3AD0@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0




----------------------------------------
> 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/
>
>
>
>
>
>
>
> _________________________________________________________________
> Pour le printemps=2C Windows Live vous propose une foule des jeux rafraic=
hissants =E0 d=E9couvrir entre amis.
> http://www.messengerbillboard.be/fr/play                                      
>  =20
_________________________________________________________________
Windows Live: Keep your friends up to date with what you do online.
http://go.microsoft.com/?linkid=3D9691815=