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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.

Dora Smith
Austin, TX
----- 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,