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Re: THERIZINOSAURS FROM THE EARLY JURASSIC



--Original Message-- From: Pete BuchholzTetanurae@aol.com Date: 01 August
1998 00:02
Subject: THERIZINOSAURS FROM THE EARLY JURASSIC


>John V Jackson wrote:
><<Yup.  Three wierd discoveries within twelve months, and only George
>"Cassandra" Olshevsky's theories predicted them all.  Spooky eh?>>
>
>To which Tom Holtz replies with:
><<Very curious statement...>>

>I think that Tom was just saying that even though George predicted these
>things, he certainly wasn't the only person or first person to predict
them.

Yes.  But I did intentionally say "them all", as opposed to "any of them"
:-)


><<3)  The early Jurassic "therizino...">>
>
>This was indeed predicted by George, but it is NOT AT ALL inconsistent with
>the idea that therizinosaurs are derived coelurosaurs.
>
>Think for a sec, coelurosaurs and carnosaurs are sister taxa.  What is the
>first Carnosaur and when did it live?  The answer is Cryolophosaurus and it
is
>also from the Early Jurassic (probably).  What does that mean?  It means
that
>coelurosaurs also had to be living in the Early Jurassic too.
>
>There is also the Middle Jurassic coelurosaur skull Proceratosaurs which I
>don't see anyone putting up a fuss about.
>
>Eumaniraptorans were around at least in the Middle Jurassic because there
are
>dromaeosaur teeth from that time.  That puts the origin of the
>Maniraptoriformes at a time BEFORE that.
>
>OVIRAPTOR HYPOTHESIS: if therizinosaurs are oviraptors, an Early Jurassic
>origin is not at all hard to believe.  Holtz 1994 placed them within
>Arctometatarsalia as the outgroup to the Tyrannosaur + Bullatosaur group,
and
>Sereno 1997 placed them as basal Maniraptora.  Since Maniraptoriformes HAD
to
>exist at least in the Middle Jurassic, probably sooner, there is no great
leap
>to say later Early Jurassic.
>
>BULLATOSAURIA HYPOTHESIS: if therizinosaurs are bullatosaurs, an Early
>Jurassic origin is not that hard to believe either.  Arctomets had to exist
in
>the Middle Jurassic at least, and troodonts and ornithomimosaurs had
diverged
>already by the late Jurassic (Koparion), and some claim now that there were
>Morrison Tyrannosaurs too (Stokesosaureus).  So, a Bullatosaur
therizinosaur
>in the Early Jurassic is not exactly a stretch.
>
>People at first might find it hard to believe that there were a lot of
>supposedly "advanced" coelurosaurs running around in the Middle and Early
>Jurassic, but realize that they HAD to be simply because a true bird was
alive
>before the Jurassic was finished.
>
>Because Oviraptors, Dromaeosaurs, and Arctometatarsalians are known from
>complete remains in the Late Cretaceous almost exclusively, many people get
>the impression that they lived JUST in the Late Cretaceous, but this simply
is
>not the case.  The Phylogeny INSISTS that they (or their stem-group
>"ancestors") had to exist before then, most probably in the Middle and
Early
>Jurassic.


I got the impression that theory mentioned certain forms which have only
been found in the K as giving rise to theriz...s, and doubt as to which
particular one was the reason for mentioning a generalised coelos..
ancestry.

On the other hand, if a very early coelos.. is supposed to be the theriz..'s
ancestor then I have to admit, that theory does predict the new find.  The
reason this explanation didn't occur immediately to me is that, while
ovirapt..s and bullato..s must of course have had J & T ancestors, they did
of course go via  Archaeopteryx :-)



> <<I'm pleased he was happy.  However I don't expect him or Kevin Padian,
when
> referred to in the role of world experts, ever to mention K-BCF>>
>
>What is K-BCF?

It is my notation for a BCF theory restricted to the Cretaceous - that many
(in the Late K and N. hemisphere most) theropods were ex-flying.  Probably
synonymous with "the secondarilly-flightless" theory.


>Also, I think it best for you to wait a year or two, there just might be
some counter >ground-up papers published, perhaps even by some list
members....


Good!  I'm sure it's going to happen.  But when you say "wait" . . .?


> <<. . . which incidentally is adhered to by a respectable section of
frequent
>contributors to this list.>>
>
>Which of course amounts to a while pile of nothing.  No offense to George,
but
>just because people agree with him doesn't mean he is right :-)

Doesn't mean we all have to be airbrushed out of existence either!



John V Jackson