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Re: tiny-armed theropods
Mickey Mortimer <email@example.com> wrote:
> Tim and I have had this battle enough times that we're familiar with each
> others' opinions and
> talking points, but I couldn't pass this up...
And I can't pass up responding. :-)
> By that reasoning, we'd have to include Passer in the analysis too, which I
> don't think you'd agree
> with. Just as we can use our extra-analysis knowledge to be fairly certain
> Passer is closer to
> e.g. Anser, Yanornis, Confuciusornis etc. than to dromaeosaurids,
> troodontids, oviraptorosaurs,
> etc., we can use it to be fairly certain Troodon is closest to Zanabazar,
> Talos, Saurornithoides
> and such. There's no need to include every definition-related taxon in an
This is a non sequitur. _Passer_ exists. It's a real animal - and a
real taxon. However, if _Troodon_ becomes a nomen dubium, it is no
longer a valid taxon. It therefore no longer represents a once
living, breathing animal. It is *just* a name. As a nomen dubium we
are precluded from referring any more material to it. If _Troodon_ is
a nomen dubium then, no, I can't be certain that _Troodon_ is closest
to _Zanabazar_, _Talos_, and _Saurornithoides_ because there is no
such thing as _Troodon_!
This separates a nomen dubium from other taxa based on poor material
that is nevertheless diagnostic. For example, nomina dubia such as
_Deinodon_ and _Trachodon_ are no longer relevant to discussions on
tyrannosaur or hadrosaur phylogeny. So it's ridiculous to include
them in a phylogenetic analysis, or (and this directly addresses your
point) even treat them as taxa. No one talks about _Deinodon_ and
_Trachodon_ as if they were real, distinct animals. As nomina dubia,
they are merely names.
> Just think of how few analyses include Enantiornis, Therizinosaurus,
> Megalosaurus, Spinosaurus,
Yes, but you *could* include these taxa in an analysis, and it would
be a productive exercise to do so. At this stage, all are considered
valid OTUs. By contrast, when nomina dubia are put into a
phylogenetic analysis, it would solely be for bookkeeping reasons.
> As I've said before on the DML, people just cherry pick from the ICZN and
> make up their own
> rules, such as those involving nomina dubia. They see their own subjective
> ideas of stability as
> overruling the ICZN, and if the majority follows them, what can we do but go
> along with the
> arbitrary flow?
And more power to them. The ICZN should serve the community, not the
other way round. If the ICZN rules say Deinodontidae should be used
instead of Tyrannosauridae, I say it's the ICZN rules that are wrong.