Re: Protoavis?

[Jonathon Woolf <jwoolf@erinet.com>]

Jonathan R. Wagner wrote:
> 
> At 06:39 PM 10/18/97 -0700, you wrote:
> >Fascinating.  It's been quite a while since I saw a reply to one of my
> >posts in which the replier did such a comprehensive job of jumping to
> >wrong conclusions and substantively misinterpreting just about every
> >line.
>         I am sorry you feel this way. Perhaps this might inspire you to
> construct your future posts in a manner which more accurately reflects your
> views.

OIC.  _YOU_ jump to conclusions and proceed to browbeat me for thing I
never said, and that's somehow _my_ fault for not phrasing things in the
particular jargon dialect that you prefer to think in. 

> 
> >The only photograph I have of _Protoavis_ is in Lessem's book.  It shows
> >skull, forelimb, a nearly complete spine, most of a hindlimb below the
> >knee, and a partial sternum.  Nothing else.
>         Perhaps, then, you ought to avail yourself of better sources before
> positing such questions to the list.

Perhaps you ought to wake up and realize that I CONSIDER THIS LIST TO BE
A SOURCE OF INFORMATION, AND MY ORIGINAL MESSAGE WAS A REQUEST FOR
INFORMATION.  Christ on a goddamned minibike, I've never _seen_ such
thin-skinned people!  Not among creationists, not among animal
rightists, not even among fanatic liberals.  Is there even _one_
so-called "professional" on this list who doesn't regard simple
questions as personal attacks on his worth as a human being?  Why is it
that a simple question is seen as a call-to-arms for the DinoList
Inquisition?  

> >Incidentally, I did say "_IF_ no details of the shoulder anatomy are
> >known".  If.  Conditional.  As in, "I am not sure this is true, but
> >assuming it is, then . . ."
>         This is a rather weak excuse, don't you think? 

It's not an excuse at all.  It's exactly what I wrote and exactly why I
wrote it that way.

>         If we are to persue a menaingful scientific dialoug, we must be sure
> that we have commonality of definition and precision of usage. 

Would it be too much to ask that you remember that not everyone on this
list is a degreed paleontologist, and not everyone is interested in
getting the jargon exactly right? 

>         So, while the "vernacular sense" may be quicker ("non-avian" adds
> two whole syllables to your statement. Hardly crippling...), it is hardly
> easier to understand, 

It is for me.  Why isn't it for you?  Not enough jargon?

> As
> far as _Protoavis_ is concerned, excessive reptition of a supposed
> bird-dinosaur "dichotomy", whether real or as an artifact of speach, can
> only result in misrepresentation and misinterpretation. 

Would you be snarling this much if we were talking about, say, dogs vs.
other members of Order Carnivora?  Would you be insisting that I say
"canid carnivores and non-canid carnivores?"  I didn't think so.

>         The very fact that this animal was preserved suggests that it was a
> part of a radiation which may have included other taxa more closely related
> to it than to all other known taxa. Thus, it is certainly possible that it
> is the "sole known member of a lineage of tetrapods for which no other
> member is yet known". This, however, has nothing to do with whether we can
> say what other taxa are most closley related to it.

Be that as it may, if we had only one partial fossil of a serval, and no
other fossils of any animal in the Felidae, nor of any potential
ancestor for it, we couldn't say a whole lot about exactly how the
serval was related to other carnivores.  Unique skull, unique teeth
pattern, unique legs and feet . . .  Nor, with only one fossil of
_Protoavis_ can we say a whole lot about exactly how it was related to
other dinosaurs.  Cladograms are not Divine Revelation.  They can be
wrong.

> >Why is such a scenario impossible?  Or even implausible?
>         Read Chatterjee's paper. Or for that matter, Lehman's work on the
> Dockum. You tell me.

If I knew, I wouldn't be asking.  If you don't know, then you've no
right to be hammering me for asking.  

> 
> >Does the local stratigraphy rule it out?
>         As I recall, and don't quote me since it's been a while since I went
> out to Post, the fossils are found in coarse-grained lenses in the redbeds
> of the Dockum group. Redbed above them, redbed below them, redbed on all
> sides of them, etc. The depositional of the fossils was regarded as being
> contemporaneous with the surrounding strate.

Good.  A direct answer to my question: as far as you know, the local
geology and stratigraphy don't seem to support the hypothesis that
_Protoavis_ was somehow transported and redeposited from Jurassic to
Triassic strata.  Now, why didn't you just say that in the first place,
instead of rambling at length about irrelevant semantic quibbles and
wasting both our time telling me stuff I already know? 

> >You're jumping to conclusions again.  I am not saying that _no_ fossil
> >is acceptable as a bird unless it had feathers.  I am saying that in my
> >mind, PROTOAVIS is not acceptable as a bird unless somebody shows it had
> >feathers.  Extraordinary claims require extraordinary evidence.  A bird
> >in the Cretaceous is not an extraordinary claim.  A bird in the Triassic
> >is.
>         This is unacceptably poor reasoning. Is the presence of birds
> delimitied by the oldest occurance of feather preservation? 

Given how similar some theropod dinosaurs are to primitive birds, in my
amateur's opinion, the answer is yes.  For Late Jurassic and earlier
fossils, you cannot assume you have a bird based only on skeletal
characteristics.  Remember, if it didn't have feathers _Archaeopteryx_
would be classified as just a small, odd theropod.  Only the feathers
mark it definitively as a bird.  And remember also how _Mononykus_ has
flip-flopped from bird to nonbird several times based on different
interpretations of its skeletal features. 

> This is not the
> way paleontology proceeds. Whether or not _Protoavis_ is hypothesized to be
> a member of the Avialae is not directly related to whether feathers are
> preserved, but to a suite of derived characters, one of which might be
> feathers. 

Cladograms can be wrong.  Subjective interpretations can be wrong.  I
want to see a smoking gun, preferably with fingerprints on it.  In the
case of _Protoavis_, that means unmistakable evidence of feathers, and
preferably flight feathers.  

>         We should not allow our concept of the stratigraphic relationships
> to affect our understanding of the phylogenetic relationships. As I just
> finished pointing out to someone else, we use phylogeny and stratigraphic
> position independently to evaluate the stratigraphic range of organisms. If
> we allow stratigraphy to dictate our concepts of phylogeny (which is then
> extended to the stratigraphic ranges of fossils, we are engaging in circular
> reasoning.

Excuse me?  The relative age of two fossils should play no part in
determining their phylogenetic  relationships?  OK, I hereby declare
that _Protoavis_ is a direct descendant of _Deinonychus_ by way of
_Archaeopteryx_.  There.  Problem solved.  

-- JSW

PS: According to the geology I learned, phylogenetic relationships play
no part in stratigraphic correlation.