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Shy mani.s; floating continents.



Sincere thanks to all for the reports on the Ostrom do.

Tom said:
"Great Paul: Had seen a lot of this particular work in various stages
before,
so not too much was new to me (although I really liked his _Caudipteryx_
restoration: the best done yet.  "

Great indeed - and I know what I'll be getting for Christmas!


"Yes, the pubis looks to be vertical.)"

I was going to ask about that if you hadn't said it.  Both Cx & Px?  Anyone
seen a glimpse of any uncinate processes on Cx/Px ?  Might look good on a
putative ancestor of Oviraptor.

??Also, incidentally, if the Yunnan therizinosauroid IS a therizinosauroid,
and our phylogenies are close to the actual tree, then the basal divergence
within Maniraptoriformes occurred by the Early Jurassic, and possibly
earlier.?

Ralph Ch. said:
"Missed Sankar though, ..."

He's pausing a moment for the world to catch up with him.  Mainstream by
August!

But "the basal divergence within Maniraptoriformes occurred by the Early
Jurassic, and possibly earlier? has other evidence too.  Dredging through
the treasure trove of Can. Jnl. Earth Sci. 30, Oct/Nov 93, gave the nice
definitive statement of continent contacts in Dale Russell's article on
p2002 I've been groping for.  May not turn out to be perfect, but it's very
useful anyway.  (It also revealed a use of 'dependant' as an adjective -
this gets through spell checkers because of the noun.)  Food for thought on
the continent of origin of various feathered forms; Central Asia is thought
to have been on its own for 60mys between mid J and the Aptian/Albian, so we
have "man on the Clapham omnibus"-style feathers inside and outside C.Asia
in the middle of that period.

Judging by first appearances of various types pre Aptian/Albian, Russell
suggested: (some of it may be contentious today...)

Neopangeans: (Dale's Neopangea: everything minus China and Siberia (ie
everything minus "Central Asia".  Were China & Siberia considered to be
apart at any time?).) :

Droms & ornithoms;
also cetios, diplods, dicraeos, nodos, iguans.


>From Central Asia:

Ovi's & troodonts ;
also: segnos, shunos, mamenchs, ankyls, ceratops, pachycephs. (I am not sure
of what pre Aptian/Albian ovis in C.Asia he had in mind.)

When examples of droms, ornithoms, ovi's & troodonts are found with (the
remnants of) complex "proper feathers", the divergence dates will have to be
at least as early as mid J according to the conventional theory.  Of course
this only if there was total effective isolation of Central Asia - though it
would be hard to prove continuous isolation since it relies on types not
being "there" for which we can only have an absence of fossils as
evidence... or some theory we can trust of time and place of the origin of a
group - which itself depends largely on what we believe about connectivity.


He concludes with: "This sketch for the biogeographical evolution of
terrestrial vertebrates through J & K can easily  be falsified.  For
example, one diagnostic element of a whiptailed diplodocid from mid J China
or of a tyrannosaur from lower K Argentina would be fatal to it."
Presumably it would be just as bad if the tyranno came from the Morrison
though I'm not exactly sure why he thought tyrannos originated in C.Asia.

Unfortunately the arctometatarsalians have been split - ornithoms from
Neopangea, troodonts from C.Asia.  Sinosauropteryx/Compsognathus are also
split.


It would be possible to say a lot more if we knew for certain just how
isolated C.Asia was pre Aptian/Albian.  We're almost at the point where we
can offer a choice:  Early J evolution of flight feathers, or something not
much more advanced than Archae flew between C.Asia and Neopangea.  Almost.
We have reasonable evidence that Archae was a good island hopper.  I'm not
bothered about splitting the arctos, nor about early Neopangeal tyrannos;
I'm more concerned about splitting Sinosauropteryx/ Compsognathus.