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Re: "Megapnosaurus" says farewell...
On Wed, 13 Feb 2002 00:02:24
In a message dated 2/4/02 5:09:11 PM Pacific Standard Time,
<< There is absolutely nothing to designate whether two animals should be put
in the same genus or two separate genera. I mean, if I wanted to I _could_
place _Syntarsus_ (the beetle!) and a rabbit in the same genus. Who would
stop me? It may seem ridiculous...but there is no convenient definition, a
la species. >>
>Well, then your genus, since it would have to be a clade, would also include
> all other arthropods, all chordates, and a bunch of other invertebrate
> These would, for convenience, have to be subdivided into subgenera,
> subsubgenera, and so forth. So eventually you'd be back where you started,
> only at a different taxonomic level.
Yes, exactly. I'd be back where I started: a taxonomic mess. Certainly
recognizing two genera in this instance (_Syntarsus_ and any genus of rabbit I
choose) would be more convenient, as it would minimize the messy subgenera,
etc. But, it is still as subjective as grouping rabbits and _Syntarsus_ into
the same genus. Convenience, like subjectivity, shouldn't be what guides
scientists. Otherwise, Avogadro's number could be designated as 6.0 x 10^23.
Convenient? Yes. Correct? Only partially.
><< I have never quite understood why _Psittacosaurus_ has something like
>seven or eight valid species, but _Coelophysis_, _Syntarsus_ (Raath),
>_Eucoelophysis_, etc. were placed in separate genera. It's aesthetic
>philosophy, not science sensu stricto. >>
>So far nobody has been able to come up with a consistent way to group
>together the various species of Psittacosaurus. You either have x species or
>x genera. They all look enough alike that the species level is considered
Exactly. Nobody has been able to subjectively come up with a consistent way to
group the species of _Psittacosaurus_ into anything but one genus. In this
case, as George said, the species level is _considered_ more appropriate.
However, there is no widely-accepted definition or principle that merits this.
I think we all know that.
Dino Land Paleontology
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