Re: More on the data used in classification

["Mickey Mortimer" <Mickey_Mortimer11@msn.com>]

Chris Fisher wrote-

> According to this (Sereno's) analysis, if I am interpreting it correctly,
> then the following have a semilunate carpal made up of two carpals ( 2
> separate element ):
> Allosauridae

Actually, this is variable.  Madsen (1976) reports fourteen of eighteen
Allosaurus specimens fuse distal carpals I and II, regardless of maturity.
It appears fused in Acrocanthosaurus.

> Therizinosauridae ( I thought Alxasaurus had 2 separate carpals, but
others
> have one single element )

Alxasaurus does have separate carpals.  Beipiaosaurus is said to have a
semilunate identical to Deinonychus, suggesting it's fused.  However, it is
also said to have both a semilunate and a distal carpal I, suggesting it's
unfused.  Confusing situation.  Therizinosaurus shows either separate
carpals, or partially fused ones.  They are at least articulated together in
the figure, but I cannot read which condition is present.

> Ornithomimidae ( I thought it was degenerate in this group - single carpal
> "block" in same place as maniraptorans but indistinct in shape )
> Oviraptoridae
> Troodontidae
> Dromaeosauridae
> Birds / Aves

As far I as I know, that's correct.  The ornithomimid situation is rather
confusing though.

> Ornitholestes ( wrist unknown - removed to Coelurus? )

True.  I think Coelurus has a small, but fused semilunate, like Scipionyx
and Nqwebasaurus.

> Compsognathidae ( wrist unknown? - but I thought it was known for
> Sinosauropteryx )

Three small carpal elements are known for Compsognathus, but they haven't
been identified precisely.  Sinosauropteryx hasn't been described in detail,
but Azuma and Currie (2000) do code it as having more of a semilunate than
Allosaurus, so....

> Alvarezsauridae ( probably because forelimb is so transformed? )

Well, the carpals are certainly fused :-)

> Tyrannosauridae ( I thought it was degenearted as in ornithomimids -
though
> I think one )immature/subadult specimen shows semilunate condition of one
> fused element ).

You're correct in that a subadult shows a similar condition to Coelurus,
with a small semilunate.

> Caenagnathidae ( wrist unknown? )

Indeed, no carpals are known.

> Is this correct ?? Many of Sereno's views appear to differ from Thomas
> Holtz's

I trust Tom Holtz any day :-)

Mickey Mortimer