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RE: SVP Preview
Mickey Mortimer wrote:
> Untrue. He states (in his 2002 SVP abstract) that Metriacanthosaurus is
> "more closely related to Allosauroidea" than to Spinosauroidea
> (containing megalosaurids).
Then this clade should be called Megalosauroidea, shouldn't it?
Interestingly, Allain alludes to _Megalosaurus_ being a possible _nomen
dubium_, with the name restricted to the type dentary.
And on the topic of sauropods...
> Titanosaurus? madagascariensis is a good example. The holotype is not
> nomen dubium, as Curry Rogers and Forster (2001) state parts come from
> Rapetosaurus, and parts from the new saltasaurine. One of the latter
>taxa should be kept as madagascariensis, the other given a new species
> name. Just because a specimen is composite doesn't mean the taxon
> associated with it should be forgotten. Anyway, the single caudal
> vertebrae preserved in the T. madagascariensis holotype were diagnostic
> enough to refer to the proper taxa, why not those that make up T.
> indicus or T. blanfordi?
Good question. It all boils down to at what level the caudals are
diagnostic. _T. madagascariensis_ has rather "blocky", square-shaped
caudals. _T. blanfordi_ has long, cylindrical caudals (successive revisions
of this species have referred those caudals of different morphology to _T.
madagascariensis_). _T indicus_ and _A. septentrionalis_ have tall and
laterally compresed ("flat-sided") caudal centra.
Now, the morphology of the caudal vertebrae is often sufficient to determine
what titanosaur taxa they *do not* belong to. For example, the rather
blocky caudals of _T. madagasariensis_ are very different from the lower,
more dorsoventrally compressed caudals of saltasaurines. However, this
"blocky" caudal morphology may not be unique to _T. madagascariensis_. If
it is, then the species may be valid, and the Indian and Malagasy titanosaur
material can be referred to it. However, the cylindrical caudals
"diagnostic" for _T. blanfordi_ are seen in other titanosaurs - e.g.
_T. indicus_/_A. septentrionalis_ is a rather different mess - the validity
(or otherwise) of these species is something I'm looking in to.