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RE: Eodromaeus, new basal theropod from Triassic in Argentina



  My argument does not presuppose that all dinosaurs were squamous rather than 
"fuzzy," but is based only on the logic of presupposition involved. It is 
likelier that many dinosaurs, based on direct evidence and their own bracketing 
(most of them sauropods and ornithischians, were squamous, but the issue 
depends on at which point we consider the squamous integument to have taken 
over (if it did) or whether size is a factor:  very few lagerstaetten preserve 
sauropodomorphans, larger ornithischians, larger theropods in the same detail 
they do the smaller-bodied forms (>3 meters seems to be problematic).

  I would caution direct evidence as the best explanation for integument type, 
but logical inference projects two bases for reasoning an assumption that 
"fuzz" can be assumed _a priori_ for the basal Dinosauria, and would permit one 
to assume basal sauropodomorphans might actually be "fuzzy" and not squamous.

Cheers,

Jaime A. Headden
The Bite Stuff (site v2)
http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)





----------------------------------------
> Date: Sat, 15 Jan 2011 02:37:31 -0800
> From: erikboehm07@yahoo.com
> Subject: RE: Eodromaeus, new basal theropod from Triassic in Argentina
> To: pristichampsus@yahoo.com; dinosaur@usc.edu; qi_leong@hotmail.com
>
> I thought there were skin impressions of sauropods, hadrosaurs (indeed, a 
> near complete "mummified" hadrosaur), and theropods that showed a covering of 
> scales.
>
> I also didn't think that the bristles such as found only on the 
> psittacosaurus tails were homologous with the maniraptor "fuzz" or feathers.
>
> Of course, there are good reasons why semi-aquatic crocs, large dinos, etc, 
> would lose fuzz.
> But to my limited knowledge, the most parsimonious hypothesis is that the 
> maniraptor fuzz was not ancestral, and neither were the bristles seen on some 
> Ornithischia.
>
> --- On Fri, 1/14/11, Jaime Headden  wrote:
>
> > From: Jaime Headden 
> > Subject: RE: Eodromaeus, new basal theropod from Triassic in Argentina
> > To: "Jason" , "Dinosaur Mailing List" 
> > Date: Friday, January 14, 2011, 10:32 PM
> >
> >   The argument for non-squamous integument is not a
> > fanciful one when dealing with any basal dinosaur. The issue
> > with regards to *Tianyulong* especially evokes an integument
> > much akin to that of *Sinosauropteryx*, preferring then an
> > argument of parsimony: It is easier to conceive that
> > integument shifted from scales to "fuzz" once than it is to
> > assume it did so repeatedly throughout Dinosauria. Whether
> > parsimony forms the better argument over any other is to be
> > seen; the next contravening hypothesis, which I assume
> > Jura/Jason may prefer for the moment, is that all Dinosauria
> > should be seen to be squamous (like crocs and other
> > archosaurs for which integument is known) unless proven
> > otherwise, but this is not the null-hypothesis. Instead,
> > based evenly on Phylogenetic Bracketing and historical
> > assumption, we can i
> >
> >   This inference becomes greater than 50% in favor of
> > "fuzz" when pterosaurs are placed between birds and crocs on
> > the avian lineage, or even between Archosauria and the base
> > of Archosauropmorpha. In the latter scenario, with the
> > presence of feathers at one end, "fuzzy" taxa along that
> > lineage, and "fuzzy" taxa at the base, it can be argued that
> > without contradicting evidence, "fuzz" would be the likelier
> > inference, including for stem-crocs. This is based solely
> > upon Phylogenetic Bracketing. Placing pterosaur4s closer to
> > birds than crocs should only increase the likelihood for one
> > lineage of -- rather than the whole of -- Archosauria, but
> > weighs greater preponderance on the argument that "fuzz" is
> > the null hypothesis of integument.
> >
> > Cheers,
> >
> > Jaime A. Headden
> > The Bite Stuff (site v2)
> > http://qilong.wordpress.com/
> >
> > "Innocent, unbiased observation is a myth." --- P.B.
> > Medawar (1969)
> >
> >
> > "Ever since man first left his cave and met a stranger with
> > a
> > different language and a new way of looking at things, the
> > human race
> > has had a dream: to kill him, so we don't have to learn his
> > language or
> > his new way of looking at things." --- Zapp Brannigan
> > (Beast With a Billion Backs)
> >
> >
> >
> >
> >
> > ----------------------------------------
> > > Date: Fri, 14 Jan 2011 07:56:57 -0800
> > > From: pristichampsus@yahoo.com
> > > To: dinosaur@usc.edu
> > > Subject: RE: Eodromaeus, new basal theropod from
> > Triassic in Argentina
> > >
> > > --- On Fri, 1/14/11, Jeff Hecht  wrote:
> > >
> > > > At 2:55 PM +0000 1/14/11, David Howlett wrote:
> > > > >Interesting how the pop culture image of
> > small
> > > > predatory dinosaurs is slowly beginning to shift
> > - did
> > > > anyone else notice that the illustration in that
> > article
> > > > included a fuzzy layer of down? Obviously there
> > is no
> > > > evidence in the slightest for this, but it does
> > demonstrate
> > > > that the concept of feathered dinosaurs is
> > becoming
> > > > ubiquitous - amazing considering that even a
> > decade ago
> > > > there was still a lot of resistance to the idea
> > in the
> > > > mind's eye of the public!
> > >
> > > +++++++++++++++++++++++++++++++++++
> > >
> > > *Ugh* yeah, it's annoying as crap. I don't think the
> > illustration is a sign of the public's increasing acceptance
> > of fuzz on dinosaurs. I believe it has more to do with the
> > paleoart community, with many (if not most) of the high
> > profile paleoartists preferring the fuzzy look over the
> > scaly one.
> > >
> > > Jason
> > >
> > >
> > >
> >
> >
> >
> >
> >
>
>
>