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Boundaries between taxa (was Re: AMARGASAURUS SATTLERI (pretty long)
This seems an odd arguement.
Especially since the EXACT SAME TAXONONIMIC SYSTEMS used in paleontology
are used to to draw boundaries between taxa of extant aniamls today, who
have a very high percentage of known morphological types (99.9% in all
species known in terapods, as an example (number is NOT based on any
study, I made it up and it sounds about right).
So by this arguement we could only group animals we know less of than we
know of large numbers of extant aniamls? The logic seems off.
I understand what you are saying about every aniaml that ever lived, as
taxa is assigned by paleontologists by morphology AS WELL AS along a
timeline and the TIMELINE creates the situation you are describing
since animalA's descendents and relatives ON THE TIME LINE eventually
must be recognised as animalB instead of as animalA and that hazy
in-between time is what you are describing, but for extant animals that
are well known, this may not be such an easy all-inclusive statement to
Someone still puts them into taxa after all.
> I'm not sure what you're asking. Of course, morphology, genome, etc., are
> different in different taxa. But if you were confronted with every
> individual organism that ever lived, morphology and genome would appear to be
> pretty much continuously variable, without any convenient breaking points
> between taxa.
> So, yes, in that sense, it is the gaps in the fossil record and fortuitous
> survival (and probably, in a few cases, fortuitous sampling of living
> populations) that allow us to draw boundaries between taxa.
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