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From: Bart Singer <email@example.com>
> For what it's worth, I like the idea of a FAQ list and have a few questions
> that might be appropriate for such a list.
> 1) What is a dinosaur?
Starting with a hard one, I see.
This depends a little on what school of taxonomy one subscribes to.
The basal boundary is based on the presence of certain unique
derived characters (relative to stem archosaurs - aka thecodonts).
Dr. Holtz probably has the list of these (I do not, just now -
though after Dr. Holz answers, I hope I will).
For a cladist, this is sufficient - all archosaur descendents
with these derived characters, or more derived version yet, are
dinosaurs. This will almost certainly include birds.
For others, it must be decided whether to include all descendents
of this basal dinosaur or not. In general, such people choose to
exclude birds from the dinosaurs. Exactly where to place the
dinosaur-bird boundary in this case is still not entirely firm.
One proposal, which I rather like, is to place the boundary at
the acquisition of the avian keeled breastbone. Until recently
I thought this placed Archaeopteryx in the Dinosauria, but a
recent report of a specimen of Archie with a keeled breastbone
suggests that Archie is a bird even by this definition.
> 2) What are the major groupings of dinosaurs?
Theropoda (including Herrerasauria)
Sauropodomorpha, divided into Prosauropoda and Sauropoda
Stem Ornithischians (which I call Dolichopoda)
Thyreophora, containing Scelidosauria, Stegosauria, and Ankylosauria
Marginocephalia, containing Pachycephalosauria and Ceratopsia
The first three comprise Saurischia, the remainder comprise
Note, some people would include Segnosauria as a subgroup
of the Theropoda, others would seperate the Herrerasauria as
a seperate group.
> 3) Where can I get more reliable information (books, videos, etc. perhaps
> including some comments as to usefulness)?
Almost any book by Dr. Norman is good (he has several popular
I will try to get some more in a day or two.
> 4) Where can I see dinosaurs (museums, digs, etc.)?
Peabody Museum at (I believe) Yale University is good.
The Smithsonian Institute in Washington DC is good.
The Denver Museum of Natural History is good.
The peace of God be with you.