[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Say this slowly: theropoda is paraphylitic, theropoda is paraphlyitic.....



Eric Lurio wrote:

<It's interesting to note that none of the proponents
of the dino/bird nexus have even *thought* of the idea
that theropoda might be paraphyletic. I mean 
bipedalism is known from some non-dinosaurian
thecodonts and Triassic crocs. Bipedalism has evolved
a minimum of FIVE times among mammals.>

  I hope bipedalism is not the thrust of your
argument, sir. Theropoda was once consdidered two
separate groups, including Hallopoda and Theropoda,
and also the Terratosauria, the latter being seen as
rauisuchid, the the first as a combination of
herrerasaurian and plateosaurian material. Theropoda
was since reevaluated early this century (I believe)
as was shown, particularly by Huene, as a single
group. Analyses by Gauthier, Sereno, Sereno et al.,
Holtz, and others, have shown conclusively time and
again that Theropoda is monophyletic. It has been
defined as such, = {Tyrannosaurus > Apatosaurus}, and
thus will always be monophyletic. The only question
towards content has been the herrerasaurids and
*Eoraptor*, so-called herrerasaurians, and this is
also being worked out by a few parties, not the least
of which are Sereno et al., and Holtz. The host of
autapomorphies for all theropods is an extensive set
that have been retested again and again ... and is
presently not considered ambiguous considerations for
monophyly.

  Finally, basal ornithischians, sauropodomorphs, and
theropods are all bipedal, as are the purported
outgroups and probelmatic forms (herrerasaurids,
*Eoraptor*, *Psuedolagosuchus* [which has been offered
as the very next group out to *Eoraptor*],
*Marasuchus*, *Lewisuchus*; more contentious are [in
order] pterosaurs, *Scleromochlus*, rauisuchids,
etc.). All of whom are bipedal. Bipedalism is basal to
theropods, dinosaurs, dinosauromorphs,
dinosauriformes, ornithodirans, "avipodans," etc.

<The feathered "dinosaurs" found in China are exiting
and valuable finds to be sure, but has it occurred to
anyone here that maniraptors may not be dinosaurs at
all?>

  So many analyses would counter this statement.
Evidence against the exclusion of Maniraptora from
Dinosauria would require more reversals than could be
counted on the fingers of a host of *Acanthostega*.

<This latest news has given us a real treasure. A site
to look for soft-part fossils of Rheto-Liassic age.
With Kyrgistan no longer part of the Soviet Union, we
can get our scientists in there and find other and
better specimens.>

  With Kyrgyzstan no longer Soviet, this is unlikley
to ever occur; the economy is in the bilge, as it
were, and this means you will have just a slight more
luck than getting into civil-war-torn countries of
Africa with more fossiliferous promise. True, fossils
in the middle and upper Trias are key to understanding
many things evolutionarily; but evidence supported by
tests that are less than rigorous, and have been
disproved or shown to be inaccurately performed or are
based on false information, including the various
Ruben et al. papers on theropod respiration (size and
location of nasal chambers and internal nares,
relative homology of croc and tyrannosaur pelves).
Therefore, tests must be done again -- rigorously. I
_do_ look forward to reading Jones et al. when the
issue hits the shelves here in the Gem State.

=====
Jaime "James" A. Headden

  Dinosaurs are horrible, terrible creatures! Even the
  fluffy ones, the snuggle-up-at-night-with ones. You think
  they're fun and sweet, but watch out for that stray tail
  spike! Down, gaston, down, boy! No, not on top of Momma!

__________________________________________________
Do You Yahoo!?
Get Yahoo! Mail - Free email you can access from anywhere!
http://mail.yahoo.com/