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Re: Non-serpentine lacertids (was RE:WHAT'S GOING ON?)

On 2 Jul 2000 archosaur@usa.net wrote:

> I agree with this up to a point. While, yes we should look at things from an
> evolutionary perspective, going around calling tyrannosaurs and ceratopians
> "non-avian dinosaurs" is both confusing and unwarranted.

You *could* just call them "dinosaurs".
> Now, cladistically snakes are lizards, just like birds are dinosaurs,

Not really -- "lizard" isn't a formal taxon, and even Lacertilia hasn't
been incorporated into phylogenetic taxonomy, TMK. (The equivalent would
be non-serpentean [or is it ophidian?] Lepidosauria.) No formal taxonomic
system has anything to say about what is a "lizard" and what isn't.

Dinosauria, however, is a formal taxon, and as such has formal usage.

> To summarize,  a sauropod is a dinosaur, ankylosaurs are dinosaurs,


> psittaciformes are birds and so are falconiformes.

And they are also Dinosauria, using the phylogenetic definition.
> _Caudipteryx_ and _Rahonavis_ are non-avian and/or avian theropods (or better
> yet, non-avian/avian maniraptorans).

_Caudipteryx_ is probably related to Oviraptorosauria (non-avian) and
_Rahonavis_ is a basal avialan, possibly a basal avian, both within
> A varanid is a lizard, an iguana is a lizard. Viperids are snakes and so are
> colubrids. 

"Lizard" and "snake" are wholly vernacular terms.

Personally, I think the term "non-avian dinosaur" is overused, but for
other reasons. If traditional Dinosauria was not a desirable taxon (and I
don't consider that it was) why continue to refer to it all the time?

Indeed, most times I see the term, people are really referring to
"Mesozoic dinosaur" (in discussions of extinction) or "non-neornithean
dinosaur" (in discussions of extinction and of features that are only
observable in extant taxa). I went though my entire site about a year ago
and found this to be the case most of the time.
T. Michael Keesey <tmk@dinosauricon.com> | AIM <Ric Blayze> | ICQ <77314901>
                 My Worlds <http://dinosauricon.com/keesey>
                 The Dinosauricon <http://dinosauricon.com>