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

SV: Feathered dinos



No, birds are primitively born/hatched with down. Altriciality has
evolved secondarily several times in Neoaves (all Paleognaths and
Galloanseres have precocial young).

Tommy Tyrberg

-----Ursprungligt meddelande-----
Från: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] För Dora
Smith
Skickat: den 8 november 2009 14:25
Till: nekarius@hotmail.com; DINOSAUR@usc.edu
Ämne: Re: Feathered dinos

Well, it's actually unlikely that some of a phylogenetically broad group
had 
feathers and the rest didn't.  It's believed that actually they all did,
but 
some, like elepants and rhinos and hippopatamouses, humans and pigs,
lost 
them.   Large size is one factor in losing one's furry covering.   But
I've 
read that even tyrannosaurus were cute and fluffy as chicks.  LOL.
Maybe, 
may not, anyone seen any cute fluffy baby elephants lately?   Besides,
birds 
are born naked.    People on my bird lists keep posting photos of their
baby 
birds.

Yours,
Dora Smith
Austin, TX
tiggernut24@yahoo.com
----- Original Message ----- 
From: "Christophe Hendrickx" <nekarius@hotmail.com>
To: <DINOSAUR@usc.edu>
Cc: "Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Sunday, November 08, 2009 7:05 AM
Subject: RE: Feathered dinos



I'd like to have your opinion about filamentous integuments in dinosaurs

since I got this conversation with my teacher in palaeontology about 
feathered dinosaurs and the preservation of feathers and protofeathers.
He 
told me interesting things I was not aware of.

I was convinced that some compsognathids such as 'Compsognathus' and 
'Juravenator' were devoid of filamentous integuments. The latter are not

visible on the specimens while both compsognathids are very well
preserved 
in fine-grained sediment (I think there are both lithographic
limestone). I 
thought that some Compsognathidae did not possess these filamentous 
structure, contrary to 'Sinocalliopteryx' and 'Sinornithosaurus' were
they 
are visible. But my teacher told me that the feathers of some specimens
of 
Archaeopteryx are not preserved at all, though there were fossilised
exactly 
in the same lithographic limestone as the other specimens. Therefore,
this 
could exactly be the same with 'Compsognathus' (both the German and the 
French fossils) and 'Juravenator' and the filamentous integuments. All 
compsognathids, and therefore all coelurosaurs, possessed filamentous 
integuments, according to him. Such quite complex structure, like hairs
in 
mammals, can not disappear in a clade. It can be reduced or just be
present 
in some part of the body, but not disappear.

Besides, according to him, the discovery of a basal ornithischian (an 
heterodontosaurid) with the same filamentous integuments as the ones 
discovered in coelurosaurs therefore demonstrate that filamentous
structure 
is a condition shared by ALL dinosaurs, even sauropodomorphs,
marginocephals 
and thyreophores. However, giant dinosaurs such as sauropods, many 
ceratopsians, ornithopods and theropods would have had only minimal
"hair" 
as we can see in our living elephants and hippopotamus. That's why we
would 
find a scaly skin in some of them when we've got the impression of the 
skin...

The second part of the conversation was on the correlation between the 
presence of these filamentous structures and homoeothermy. What can we
say 
about this? If there really exists a correlation between the presence of

fuzz and homoeothermy, what my teacher would assume, than all dinosaurs
were 
homoeothermic animals. According to him, homoeothermy was already
present in 
pterosaurs, first because they were flying animals (again, he would
assume 
that all flying vertebrate are homoeotherms), second because we also
have 
the evidence of filamentous structures in some of them (but not all).

So, I'd really like to get your opinion about these points because I'm 
absolutely not knowledgeable about homoeothermy and the evolution of 
filamentous integuments.

Thanks in advance and sorry for the mistakes in English,

C.H.
http://spinosauridae.fr.gd/