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More stuff on early maniraptoriforms
At 11:31 AM 11/12/98 +1100, Adam Yates wrote:
>Zinke, J. 1998. Small theropod teeth from the Upper Jurassic coal mine of
>Guimarota (Portugal). Palaontologische Zeitschrift 72: 179-189.
Hey, I've got to check that one out!! Hadn't seen it yet. Thanks for the
However, as Chris Brochu mentioned, identifying archosaurs by their teeth
only can be tricky. If the taxon in question has some unique morphology
(i.e., the premax teeth of tyrannosaurids; ceratopsid teeth; etc.), then if
you find an isolated example you can be fairly secure it is either that
taxon or one which was previously unknown.
However, since many archosaurs seem to have very generalized tooth forms,
these become much more difficult to identify. (Josh Smith will let us know
a lot more about this topic in the not-too-distant future!).
>[With regards to the Dry Mesa maniraptoran]:
>Mmm. Could even have been a flier. No, probably a bit too big for the
I don't know: it could be from a good sized flier. Without the rest of the
skeleton, it would be hard to say.
>Could it have migrated from another horizon?
Very little chance of that: the locality in question is pretty well studied,
and securely Morrison.
>I think I'll have to
>insist on something articulated.
Well, you can insist on a million pounds deposited in a personal Swiss bank
account, but that doesn't mean you'll get it.
By the way, what femoral features would you consider diagnostic for a
>>Greg Paul has had these ideas published in the volume for the (3rd?)
>Mesozoic Terrestrial Ecosystems Symposium, and I believe has a paper on that
>subject in the volume on the Society of Avian Paleontology and Evolution
>meeting (don't know when it is scheduled to come out: hopefully soon).
>I'm talking about "Nature", "Science", and the populars.
That would be great, sure, but when was the last time you saw a paper on
ornithischian feeding in Nature or Science? On display structures in
dinosaurs? On sauropod limb mechanics? Nature & Science take just a tiny
handful of paleo papers per year, so the majority of good papers on
dinosaurs are published elsewhere.
>>Perle, Chiappe, and colleagues discuss this subject with regards to
>alvarezsaurids in Nature, Science, and elsewhere.
>That's a start, but I don't think Luis is the best choice for selling the
>idea. (Not that Luis, anyway.)
Ideas by merit, not by source. Repeat until you get the concept.
(I think it is very funny that the case of the alvarezsaurids, which fulfill
a post-Archaeopteryx BCF prediction entirely (they are flightless forms
which are not at first glance avian, but which seem to be descendants of
feathered fliers), are ignored by some of that hypothesis' main proponents).
>I think Greg could write something boring enough to get past if he really
>tried - he's written tons of papers (though none in the given topic in the
>given journals), and even that one on dino artists for Sci. Am. I don't
>think that reason holds for him. George writes pretty damn sharply, doesn't
>he? I don't know how often he submits papers these days though.
Actually, George has come out on the list and stated point blank that he
doesn't feel it is worth his time and effort to submit papers to peer
reviewed journals. That's his choice.
>contributions to magazines, libel is usually the main objection, though
>there are many others, particularly just plain unconventionality.
Or, perhaps, that it was the *paper* that got rejected (assuming there was
even one submitted!!), not the person? I suspect that you won't believe
this, but even Sereno and Norman and Padian and others get papers rejected.
Does that mean they are bad scientists? No. Does it mean that there is
someone trying to prevent them from publishing? No. Does it mean that the
papers may not have been quite as tight as possible, that there may have
been errors in the analysis, that for space considerations the papers in
question may not have been strong enough for inclusion in the journal at
that time? Yep.
>Let me say this. There is a biologist who worked with Haldane to produce
>much of the bases on which our current understanding of natural evolution
>rests. There aren't many who could claim to have been more significant in
>the field alive today. Now if Maynard Smith isn't a big fan of cladistics,
>what is it that all these other characters know about biology that makes
>their opinions more valid than his?
Ideas by merit, not by source. The arguments as to why cladistics is
currently the favored method of analysis, and a history of the subject, can
be found in:
Hull, D. 1988. Science as a Process. Univ. Chicago Press.
(And, for the main reasons: explicit delimination of what characters are
being studied and how they are distributed among the taxa in question;
repeatablity (precisely what Dinogeorge suggested); falisifiability).
>>Okay, now we can start discussing these things nice and systematically. In
>your opinion (analysis would be preferred, but I'll have to settle for
>opinion), which of the following groupings most accurate reflects the
>phylogeny in question:
>Pinnants (First-ish member - Archae)
>| ? --Arctos
>| ? --Enants
>| ? --Uncinants
Okay, fair enough. So, an unresolved trichtomy above _Archaeopteryx_.
Now, what is the membership of Uncinants again (oviraptorosaurs and
dromaeosaurids)? Are Neornithines in that clade? Now we can begin to
pursue falsifiable questions.
Let's start with the simplest one: what characters unite these three
advanced taxa above the level of _Archaeopteryx_?
>>Or, to use your own metaphor, you are not allowed to play the game, and you
>don't give a fig about playing the game. Do you see any logical problem
>The game I am (or was) trying to play was publicity/exposure. The game I
>don't want to play is esoteric cladistics.
If you want to play the game of exposure, and you don't want to be doing
pseudoscience (which actually does get a lot more of exposure than science:
I supect more people know about crop circles than about the Milankovitch
cycles...), then submit your hypothesis to the test. If it survives, it
deserves some attention. If it doesn't, then it deserves less attention.
No more and no less can be asked for any scientific hypothesis.
Thomas R. Holtz, Jr.
Vertebrate Paleontologist Webpage: http://www.geol.umd.edu
Dept. of Geology Email:email@example.com
University of Maryland Phone:301-405-4084
College Park, MD 20742 Fax: 301-314-9661