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Re: Microraptor hanqingi, new species from China.



Brad McFeeters <archosauromorph2@hotmail.com> wrote:


> Do taxonomists in these other specialties care if genera are paraphyletic? 
>  That's the usual justification I see whenever someone splits a dinosaur 
> genus.


One point worth noting is that paleontology, by its very nature,
covers fossil taxa.  As such it tracks the evolution of groups over
time - often over a vast expanse of time.  As such, paleontology is
more likely to encounter groups that are, in retrospect, paraphyletic.


For example, if the great end-Cretaceous extinction had occurred much
earlier in the Cretaceous before hadrosaurids had evolved, then
Iguanodontidae would be monophylelic - rather than being a
paraphyletic series of outgroups leading up to a monophyletic
Hadrosauridae.  As mentioned by others, genera are often split up
because they are found to be paraphyletic.  I'll note that _Iguanodon_
has been split up into several different genera (most of them still
close together in the iguanodontian tree, but rarely forming their own
clade).  By contrast, there are several hadrosaurid genera from close
to or at the end of the Cretaceous that retain multiple species.


In today's world we are far less likely to encounter paraphyletic
taxa, because we are limited to genera and species that are extant.
Living species represent the very tips of crown clades.  In time, a
living species contained within a certain speciose genus may split off
and become its own genus; this would render the genus containing its
erstwhile congeneric species paraphyletic.  But this hasn't happened
yet.  In the fullness of the fossil record, this process happens all
the time.






Cheers

Tim