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Re: Defunct genera and _Pekinosaurus galtoni_ (was Re: Suchomimus' forcula)
<< Zounds, dinosaur genera are being sunk faster than new ones are being
No, it's just the lumpers having their turn.
In these cases I think the lumping is justified. Well-represented dino
species (_Allosaurus fragilis_, _Coelophysis bauri_, _Triceratops horridus_,
to name a few) tend to show a lot of morphological variation within the
species. David Smith's morphometric analysis of _Allosaurus_ bones
(published in a fairly recent JVP paper) showed this to be true for _A.
fragilis_. Or, to put it another way, one _Allosaurus_ species showing a lot
of variation was the most parsimonious way to explain the results of the
analysis (as opposed to several co-existing _Allosaurus_ species showing
little variation; _Saurophaganax/Allosaurus maximus_, though, does seem to
be a valid and separate species from _A. fragilis_). When you think about
it, a happy and healthy dinosaur population ought to show a lot of
In the past, when I was looking at the descriptions of _Anasazisaurus_ and
_Naashoboitosaurus_ (each based on a single skull) I remember struggling to
discern exactly what was so different between these two genera and
_Kritosaurus navajovius_. According to the hadrosaur paper in the NMMNH
volume, the difference appears to be minimal and explainable by
morphological variation, or due simply to ontogeny (revealed by comparison
with different growth stages of _Prosaurolophus_).
_Brachyceratops_ and _Monoclonius_ (for the Centrosaurinae) and
_Maleevosaurus_ and _Nanotyrannus_ (for the Tyrannosauridae) are four more
genera who have bit the dust, and to me their passing seems justified: the
most parsimonious explanation appears to be that their "diagnostic"
characters are juvenile/subadult traits. This only becomes apparent after
comparison with species for which growth series are known.
Still, if someone wants to sink one genus into another, I'm not going to
accept it blindly. I personally think _Cathetosaurus_ is quite possibly a
valid genus (it has a few titanosauriform features not seen in
_Camarasaurus_), and I have doubts about whether _Jurapteryx_ is a young
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