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Re: Archaeopteryx feathers and taphonomy.



In a message dated 96-09-27 16:53:06 EDT, davis@kahaku.go.jp (Paul Davis)
writes:

> Hells teeth!  I've never heard so much rot coming from so many sensible
> (normally!) people.

Not entirely guilty of rot, I'm afraid. Read on...

> 1. There is 1 Comsognathus specimen from Solnhofen (the other specimen is
> from another locality in France)

As I noted.

> 2. ALL the specimens of Archaeopteryx (both species) have feathers
> preserved even the partially disarticulated ones

I was not completely certain that this was the case, just off the top of my
head. But I noted that most of them were feathered.

> 3. The taphonomy of feathers is well documented and they don't just wash
> away! ( i'm angry 'cos I sweated blood writing the bloody things)

This is good to know. So, as I noted, it remains--for this reason--quite
unlikely that _Compsognathus_ was feathered.

> 4.  There are no feathers from any deposits before the upper Jurassic
> (there are many sites that should preserve them - and they are common in
> deposits which have these right taphonomic conditions - this should tell
> you something!!)

_Praeornis sharovi_ is earlier, but not everyone agrees it was a feather. A
recent post to this list, however, cites SCM data refuting the notion that it
was a plant frond.

> 5.  A canada goose has about 30000 feathers -so work out how many would be
> needed to cover a small dinosaur!!! - and still there are none
> pre-Archaeopteryx.

Exactly my point. If theropod dinosaurs were bird ancestors, we would expect
them to have been feathered, since we all agree that a complex structure such
as a feather did not evolve "overnight," and we would see more feathers and
featherlike fossils dating from before _Archaeopteryx_ than we do. But if
dinosaurs descended from feathered dino-birds, they could well have lost
their feathers secondarily, perhaps accounting for the lack of feathers in
the Jurassic fossil record.

> 6. The solnhofen Compsognathus has eggs preserved as well as it's stomach
> contents - ie the conditions were perfect to preserve feathers - therefore
> if Compsognathus had feathers they would be preserved - it didn't therefore
> they weren't. 

I agree. The Canjuers _Compsognathus_ is preserved in similar deposits with a
similar taphonomy, and it shows no feathers, either.