Re: Longisquama

["Matthew Bonnan" <mbonnan@hotmail.com>]

DinoGeorge wrote:
How do you >know< that the integumentary structures on Sinosauropteryx and
the other Chinese finds are "an ideal pre-feather stage"? How would you
recognize such a stage in the fossil record? How do you know that what you
see in Sinosauropteryx are "pre-feathers" and aren't, e.g., modified "true"
feathers? Why would you think that the resemblance between Longisquama 
dermal
structures and feathers is "superficial," but the resemblance between
Sinosauropteryx dermal structures and feathers is not?

Ditto furcula.
<<
<<

It would seem that the "pre-feathers" question would take a back seat here 
to the fact that _Longisquama_, as mentioned in so many posts already, is 
fragmentary and in some cases it is questionable as to whether the animal 
was an archosaur or a lepidosaur.  If we can't even agree on what group of 
"reptiles" this guy belongs to, how are we to judge the significance of its 
dermal structures, feathers or no?  Same with the "furcula."

While the integumentary structures of _Sinosauropteryx_ may not represent an 
"ideal pre-feather stage," it currently makes sense to look at such animals 
more closely for pre-feathers based on most current evidence which suggests 
a dino-bird link of some sort.  Since we cannot put our fingers on what 
Longi. is, it appears more reasonable at present to look to dinosaurs for 
the feathers questions.
As far as the integumentary structures of Longi. being feathers, I suspect 
this may depend on how lose your definition of feather is.  A feather is, 
after all, a modified scale.  Which brings up two good questions for the 
list: do we have an exact definition of what a feather is, and can anyone 
say more than protofeathers are modified scales?  Furthermore, do 
protofeathers have to be avian in morphology in order to be recognized as 
such?

Maybe feathers arose in the Triassic?  Maybe _Longisquama_ is the ancestor 
of arboreal animals which led to birds and dinosaurs?  Maybe.  But we need 
better evidence.  We should not reject these notions out of hand, for sure, 
but since the very identity of Longi. is in question, and since most 
evidence links dinos and birds strongly, I would argue that Longi. is not at 
this time an animal which will provide us with much in the form of testable 
insights into the development of feathers in archosaurs.

Matt Bonnan
Dept Biological Sciences
Northern Illinois University


_______________________________________________________________
Get Free Email and Do More On The Web. Visit http://www.msn.com