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Re: What Is Not a Dinosaur? (was re: Ankle Articulation in Pterosaurs)

At 07:17 PM 1/23/97 -0500, Amado Narvaez wrote:
>       What prompted my questions in the first place was a statement made
>by Currie and Koppelhus that "most of the traits that identify them
>[dinosaurs] are found in the hind legs."
        The new Novas article in JVP addresses this as well.

>       I am trying to explain to kids ranging from kindergarten through
>grade 3 why pterosaurs are not dinosaurs, and I'm not sure that telling
>them, "You'll understand it when you're grown up and learn about
>anatomy and dinosaur systematics" will work.
        Not what I had in mind at all.  You can use characters as examples,
all I meant was that you shold not tell them that any particular trait or
suite of traits *defines* dinosaurs.
>       I was surprised by the opposition to using "simple anatomical
>definitions" in defining the Dinosauria.
        This is not how it is done scientifically, and I fully believe that
children will be able to grasp the difference.

>I mean, sure, there's a
>complicated, highly scientific way to explain the difference between an
>insect and a spider, but there's something wonderfully economical in being
>able to say, "One way to tell them apart is that insects have six legs and
>spiders have eight."
        See above.  This is not at all a bad thing.  I just wouldn't go
saying that this is the *definition* of a spider. Your octopus is a good way
of explaining this:  "eight legs does not make something an arachnid.
Octopuses have eight legs, but they aren't arachnids.  Arachnids are a
specific group which is based on being a decendant of a particular ancestor.
This is just like how your family is defined.  You are a member of your
family because you are decended from your mother and father, even though you
may look more like the kid next to you than like your parents."

>       The statement "We can't afford to dummy down science to this
>level..." struck me as unusually critical. Where is the line drawn between
>"dummying-down" and "explaining in lay terms?"
        As I explained, you are not explaining in lay terms if the
explanation you give is not related to the scientific method actually used.

>Are the coffee-table dinosaur books by Lambert and Norman "dummying down?"
        Haven't read them.

>Is it dummying down
>to say that "Dimetrodon is not a dinosaur because its legs were oriented
>in a sprawled stance rather than an upright one" or "Dimetrodon is not a
>dinosaur because it lived in the Permian period."

>That will linger much longer in a child's mind than a treatise on pelycosaurs.
        True, but you don't need a treatise.  I'd be surprised if it
wouldn't be just as easy for a child to remember that animals are organized
into groups based on common decent, if that phrase is translated into
appropriately simple terms.  And the benefits of such a realistic approach
will be felt later, especially if the child does not persue a career in the

>       Finally, you mention that I should not even consider the
>suggestion that birds are dinosaurs.
        This is not what I said at all.  I simply said that the definition
of dinosaurs as "animals which did not fly" or somesuch was twice damned,
and you should try to stick to the latest theories available.

>As you may recall, I said I wanted to
>leave it as an "option," not a given. I want the kids to understand that
>some scientists believe that birds ARE dinosaurs, but that other people
>think they are just related. Why should it be wrong to present both
        There is absolutely nothing wrong with this, it is a very
responsible attitude which I don't think a lot of science teachers are
willing to take.  Please do do this.  In fact, this might be an excellent
way to highlight the pterosaur question.  You could say, for example, "Some
scientists think that birds are decendants of the common ancestor of the
dinosaurs.  What do you suppose this would mean?  That's right, it would
mean that they are dinosaurs.  Other scientists believe that birds are
decended from an slightly earlier common ancestor.  That would mean that
they are like pterosaurs, close to dinosaurs, but not actually dinosaurs."
Then you could point out the similarlities.

        Anyway, I hope this clears things up a bit.  Good luck.  It is
really nice to see that so many teachers are trying to keep their classes up
to date.


P.S. Smithsonian?  Where do you teach?
| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
| Texas Tech University                  Because your friends don't clade  |
| Lubbock, TX 79409                               and if they don't clade, |
|       *** wagner@ttu.edu ***           Then they're no friends of mine." |
|           Web Page:  http://faraday.clas.virginia.edu/~jrw6f             |