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

Re: popular vs. academic terms (Avedinosauria?)

  Thanks to Mike Keesey for correcting my last post ... I admit I have
difficulty getting the stem anchors strait....

Ken Kinman wrote:

<However, someone stated that popular ideas should conform to
scientific ideas and not vice versa. I couldn't agree more!!! For most
of the 19th and 20th Centuries, the term Dinosauria was applied by
scientists to non-avian dinosaurs, and the popular idea of dinosaur
followed suit for the most part. It was the strict cladists who came
along, and unilaterally decided to dump in all the birds and to still
keep the same name. A new name would have obviated all this confusion
(even one of Jenny's grade-schoolers pointed this out). To use
Dinogeorge's excellent example, perhaps the cladists should get a new
name for Clade A----instead of commandeering Dinosauria (cladists just
added to the imprecision of this word by what they did).>

  Hmm. The point was that because most people's popular definition was
the titanic behemoths of the past, that dinosaurs as reptiles should be
held exclusive of such novel innovators as birds, rather than lumped in
with their backward, coldblooded "predecessors"....

  Anyways, one of the main points brought up by deQuieroz and Gauthier,
in various publications, was that a perfluence of names to reflect the
ideas of how taxa should be excluded based on an impression of
something that has no metric, that these names should not be made, and
that the closest fitting taxon that does not have a definition, should
then be defined. The Phylocode follows this. It is clear this would
make people's ideas shift; that's one of the points. As for
imprecision, there is nothing except the rift between those who feel
Dinosauria equals non-birds (which it never did) or that which feels
Dinosauria is a group that stems from the common ancestor of two forms
(in which case, by the several analyses that have followed an intense,
rigorous, and wide-spread examination of birds, crocs, "thecodonts,"
and [non-avian] dinosaurs suggest that birds are not just allied to the
dinosaurs, but stem from withn a specific subset of dinosaurs,
theropods, which further analyses has supported the homology
thereof---competitive analyses have failed to use dinosaurs in
comparison to other proposes allies, or merely used ornithurines in
connection with *Archaeopteryx*).

<Like it or not, many (dare I say most?) professional biologists still 
recognize various paraphyletic groups, including Dinosauria for
non-avian dinosaurs. Michael Benton is a very prominent one among
vertebrate paleontologists (and one of those who is beginning to see
that such groups need a "marker" for any exgroup that has been

  Correct me if I'm wrong: Mike Benton has described several taxa
linking various outgroups of dinosaurs including pterosaurs and
*Scleromochlus*, and beleives birds are dinosaurs.

<It was the strict cladists who changed the meaning of Dinosauria and 
dinosaur (by dumping in all of the birds and not changing the name).>

  Endless profusion of taxa is why "they" didn't....

  Besides, I beleive the first mention of birds as dinosaurs was by
Huxley, and Ostrom and Bakker reinvigorated the idea in the late-60's
and 70's, and none of these esteemed men were "strict cladists" or
"cladists" in any fashion. Strict comparitive morphology.

  As for the meaning of Dinosauria, this has been clarifed over the
decades, but the original inclusion (*Megalosaurus*, *Hylaeosaurus*,
and *Iguanodon*) can be rephrased easily (theropod, ankylosaur,
ornithopod -- or the most recent common ancestor of a theropod and an
ornithischian, and all of its descendants, which further includes
sauropods, herrerasaurids [?], and birds). By historic reference as I
understand it, no one has "changed" the meaning of it, and by
modification through descent, have merely clarified the inclusion,
never the orignal intent. Further workers since Owen have attempted to
constrict the idea that dinosaurs could not include birds because of
the impression they were reptiles, and because reptiles were a class,
as well as birds were, could not in the least be homologous. This was a
religous perception for the most part, as it stemmed from the Linnaean
belief that life could not change, or evolve into other forms, thus all
existed at once, in perpetuum.

<Can't you see how galling it is for us to see cladists set up this
kind of confusing situation, and then say that it is the non-cladists
and the public that have misconceptions about Dinosauria (as you have
redefined it).>

  Personally, the only confusion I see is between those who see
dinosaurs as cold-blooded and equivalent to reptiles, and those who see
warmblooded birds as a subset of dinosaurs, and that ther is no
significant paradigm shift when a warmblood stems from a coldblood. It
is the idea that "reptiles" and "birds" are equivalent, when these are
vernacular, along with "dinosaurs," and Reptila and Aves (and
Dinosauria) are just names.

<We have had a name (Dinosauria) for non-avian dinosaurs for a very
long time,>

  Yes, as I stated above, this connotates the kost recent common
ancestor of a theropod and ornithischian. If birds are theropods, they
are dinosaurs as well. Period. End-Stop. Whatever.
<so please don't give the rest of us a hard time just because we want
to  enjoy the benefits of a useful paraphyletic group like this one.>

  Except Dinosauria is not paraphyletic. It's monophyletic as of the
last ten years analysis by Gauthier, Sereno, Novas, Benton, etc. who
explicitly studied this situation.

<If you want a precise scientific term for birds plus dinosaurs, come
up with a new one (like Pandinosauria or Avedinosauria):
    Avedinosauria minus Aves (A-B) = Dinosauria>

  Why no one has done this: redundant and profuse. Because the
definition does not explicityly include birds does not mean the group
does not take part in the name and its further meanings. The inclusion
of birds within dinosaurs is excplicitly stated as of Coelurosauria
(all taxa closer to Neornithes than to *Allosaurus*), and further down
the stems to the node Aves, which relatively fewer individuals have
questioned the monophyly of. Thus the phylogenetic definition of
Dinosauria was composed witht the historic meaning in mind, following
Owen's original usage, and the debates that followed, while allowing
accurate morphological relationship.

  One last point: the historic usage and therefore popular definition
of birds (Class Aves as of Linné) corresponds to modern Neornithes. By
the popular definition, and the criteria Ken has described, what we
regard as birds (including hesperornithiforms, ichthyornithiforms,
confusiusornithids, enantiornithids, archaeopterygids [taxon redundum],
etc.) would not be birds "in the popular sense". Just because they look
like birds is irrelevant. In the original texts, in fact, separate
groups were coined to unite living "suborders" of birds with those
being found by Marsh, Cope, etc., in the 1880's. Hesper birds were
considered similar to gaviiforms, fish birds were like
procellariformes, and thus by original connotation were neornitheans.

Jaime A. Headden

  Where the Wind Comes Sweeping Down the Pampas!!!!

Do You Yahoo!?
Yahoo! Shopping - Thousands of Stores. Millions of Products.