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Sinornithosaurus and Negative Evidence



It's an open question if this new feathered dinosaur, which shows barbules, 
is either a juvenile specimen of Sinornithosaurus or a new genus.

Earlier this year Xu, X., Z.-h. Z. & R.O. Prum found no signs of barbules in 
"Branched integumental structures in Sinornithosaurus and the origin of 
feathers" (Nature 410: 200-204). 

So if the new feathered dinosaur can be proven to be a juvenile 
Sinornithosaurus adults must have had them too.

But in any case it's time again to recall Dr. No (negative evidence please! 
formerly known as Dr. Thomas R. Holtz, Jr. (sorry, couldn't resist)). As he 
always reminds us that absence of evidence is not evidence of absence. 

In this case the missing barbules are used as an argument against the 
feathery structure of the integument of  Sinornithosaurus. But perfect 
fossilization is very, very rare. So when integumentary structures are found 
these may (or may not) tell us only part of the whole story. So there's (for 
now) no proof for or against barbules in Sinornithosaurus.

Regarding positive evidence: In September 1999 there was an ABC article about 
Sinornithosaurus which quoted Larry Martin as saying that he wanted to see 
fossils of lizards and other critters from Liaoning in case they show similar 
"feathers"--proving that the halos are not external integument. This would be 
positive evidence proofing that Sinornithosaurus had no barbules, not even 
any kind of feathers. But up to now no feathered frogs etc. have been found 
|-).

Cheers

Heinz Peter Bredow
Bremen/Germany

BTW: Thanks to Luis Rey for his early warning of things to come (the 
feathered dinosaur) in "My own SVP Experience (Long)" in December 2000. He 
wrote:
> Letâs say that after fifteen years of dreaming and speculating (and many
> times having withstood abuse, disbelief and scorn), finally all my
> dreams came true at the stroke of an opening drawer!

I waited and yes, it was worth the waiting.