Re: FW: Did Feathers Evolve for Dispaly? We Still Don't Know!

[Tim Williams <tijawi@yahoo.com>]

Dale McInnes <wdm1949@hotmail.com> wrote:


> You say that ....... "we now know that the simplest 
> feathers in dinosaurs such as _Sinosauropteryx_were only present over
> limited parts of it's body ...." and from this you are inferring that
> they would have had limited function in thermoregulation. As the 
> fossil stands .... fine. But are we absolutely sure that this is not 
> simply an artifact of preservation (the limited tracts of feathers)??


That was a quote from Mike Benton ("Furthermore, we now know that the simplest 
feathers in dinosaurs such as _Sinosauropteryx_ were only present over limited 
parts of its body â for example, as a crest down the midline of the back and 
round the tail â and so they would have had only a limited function in 
thermoregulation.")

As to whether the distribution of feathers is a preservational artifact... I 
don't know.  Dann asked essentially the same question.  In their very helpful 
re-description of the _Sinosauropteryx_ specimens, Currie & Chen (2001) take 
the view that the absence of feathers from most of the body is indeed a 
preservational artifact, and state:

     "Integumentary structures probably covered most of the
      body of living _Sinosauropteryx_, as evidenced by the density
      of the covering dorsal to the body and by the few random
      patches of integumentary structures that can be seen in other
      regions of the existing fossils. In the birds found at the same
      site (and all _Archaeopteryx_ specimens), feathers are only
      preserved as a corona around the body. To be preserved, it is
      important for the keratinous feathers to be surrounded by
      and in direct contact with the encasing sediments. Feathers
      lying against the skin and other tissues were generally
      destroyed as the flesh decomposed. The exceptions on the
      flanks of the body and tail of NIGP 127587 may have been
      separated from the body by thin layers of sediment."


Cheers

Tim