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Re: Lumping Spinosauridae Redux

Mike Taylor wrote-

> My new and perhaps indefensible position (I don't know if I can defend
> it, I haven't tried yet) is that it makes pragmatic sense to have a
> notion either of genus or species for fossil taxa (because it's useful
> to be able to name a taxon on a single specifier), but that it's
> essentially meaningless to have both, since there is no way to
> establish the boundaries between them.

My position is that the most important thing when deciding whether to make
two species congeneric is the monophyly of the resulting genus.  For
instance, if we would have accepted Paul's (1988) sinking of Deinonychus and
Saurornitholestes into Velociraptor, according to Senter et al.'s (2004)
topology, all dromaeosaurids would be Velociraptor.  This includes
Dromaeosaurus albertensis, which is an older name, so all species would then
be transferred to Dromaeosaurus.  Dromaeosaurus would range from
Kimmeridgian to Maastrichtian time, existing in Europe and Asia, North
America.  It would have a size range of 2-12 meters and contain more than
ten species.  This also illustrates the second most important thing about
congeneric species- ensuring placement into one genus serves a useful
taxonomic purpose.  Why bother putting all those species into Dromaeosaurus
when they are already all in Dromaeosauridae?  This ties back to Baryonyx.
Why put tenerensis in Baryonyx when they're already separated from other
taxa by being baryonychines?  Keeping species in different genera also helps
assure that when relationships of previously named species become better
known, your genus won't get sunk.  What if Suchosaurus cultridens turns out
to be a baryonychine?  If all baryonychines are Baryonyx, the latter would
get sunk into Suchosaurus.

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html