Re: "Feathery fossil shows birds aren't dinosaurs"

[Jeff Hecht <jhecht@world.std.com>]

At 9:12 PM -0700 6/22/00, Phillip Bigelow wrote:
> Is this another better preserved specimen of Longisquama that
> preserves good morphology, or is this specimen the same old
> hash-on-a-slab holotype that will undoubtably evoke comments
> like "It has a furcula!"  "No it doesn't!"  "Yes it does!"
>
> In other words, is this paper in _Science_ an example of
> rehashing old hash?

In a word, yes. They're looking at the single specimen of the 
Longisquama extended scales with a partial skeleton (head, front legs 
and torso, but no tail or rear torso. They also have five separate 
fossils of the extended scales or whatever you want to call them. 
They did have the advantage of more modern equipment for examination 
than the Russians did 30 years ago, but it's still the same specimen 
with cracks and a coating of gunk which obscure some details (notably 
critical skull details that diagnose whether or not it's an archosaur.

I have an article coming out in next week's New Scientist (Science's 
embargo is very inconvenient for a magazine that hits the streets 
Thursday morning), which I'm not going to repeat. But for the list 
it's worth thinking about a few points.

Feduccia et al are _not_ saying this was an ancestral bird. They're 
saying it's one of a number of bird-like thecodonts (the term 
Feduccia prefers) that lived at the time, and they're saying that 
feathers may have originated long before Archaeopteryx.

I see two messages in the paper which deserve to be treated 
separately. One is an attack on the whole cladistic method of 
analysis (which has stimulated a counterattack on that attack from 
the paleontological establishment). It's based on the notion that 
this is an animal with feathers that doesn't fit all the nice 
correlations of characters which show birds are dinosaurs. I'm not an 
expert, but I don't think it's a tremendously strong case.

The second is likely to get lost in the shouting over the first 
message. Longisquama shows scales have considerably more potential 
for interesting structure than is generally assumed. Whether or not 
those are true "feathers", they clearly evolved from scales. They may 
very well have evolved from scales independently of the feathers on 
true birds. Maybe we really need to take a closer look at scales to 
better understand feathers. --

Jeff Hecht     Boston Correspondent    New Scientist magazine
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