(no subject)
AJ Crowl (ajcrowlx2@ozemail.com.au)
Thu, 3 Jun 1999 08:32:54 +1000
>From: "Arthur V. Chadwick" <chadwicka@swau.edu>
>To: asa@calvin.edu
>Subject: Re: Dino-Birds
>Date: Wed, 02 Jun 1999 09:25:38 -0700
>
>At 05:12 AM 6/2/99 PDT, you wrote:
> >Hi ASA,
> >
> >Chinese researchers, in the latest issue of "Nature" [27 May 1999],
report a
> >new find of a dinosaur with filamentary integument i.e. pre-feathers,
just
> >like _Sinosauropteryx_. These filaments are clearly covering the animal
> >rather than deceptively seeming like sub-dermal structures, as in the
case
> >of _Sinosauropteryx_, and the individual filaments seem to have hollow
cores
> >like true feathers. They're obviously not flight feathers, but they are a
> >possible preadaptation ready for transformation in gliding arboreal dinos
or
> >leaping cursorial dinos.
>
> They are not "feathers" in the technical sense, and to suggest that they
>are something on its way to becoming feathers is of course pure speculation
>(and your privilege). Fully competent "modern-type" feathers are already
>present in the Jurassic Archaeopteryx, well below these Cretaceous
>dinosaurs, and probably on creatures found lower still in the geologic
column.
>I am not aware of any feathered dinosaurs that might have resulted from
>these "preadaptations".
>Art
>http://geology.swau.edu
>
Well _Archaeopteryx might well be described as a feathered dino... And other
dinosaur-like forms are known. From an evolutionary perspective the
pre-feathers indicate that a spread of coelurosaurs porbably had them and
hence raw-material was there for natural selection to shape. Not quite
enough to convince a sceptic like yourself Art, but enough to convince me
that the dino-bird link is reasonable and well supported.
As for the timing... the group of dinos from which the new species came has
an extensive prior history and being separated morphologically from the
related bird-like dromaeosaurs suggests their last common ancestor had
pre-feathers. Feathers are chemically related, not to regular reptilian
scales, but rather skin structures possessed by crocs - "scutes" - and
dinosaurs had these also. Filaments were produced instead of scutes in some
dinos and seemed to serve an insulating role like the feathers of penguins.
To really settle the case more dinos with clear feathers need to be found,
and I'm suggesting they will be - if the right sediments for preservation
exist.
I'd like to hear what you actually believe about the distribution of life
through time, Art. Did it all come into being with Eden or was there some
prehistory? If the Earth is old as you seem to believe then how does it all
fit together? I suppose in a literal reading of Genesis the six-days could
be seen as recent, but the dark world of tohuwabohu could be old with some
sort of dense cloud covering. When I was a Gap theorist the post-Judgement
conditions of that Earth seemed obvious, since they're an exact parallel for
Noah's Flood... darkness, water and the wind blowing it away... What's your
view?
Adam
>
Is your God image an idol?