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Re: THERIZINOSAURS FROM THE EARLY JURASSIC



Jonathan R. Wagner wrote:
> 
> 
> >Most characters exhibit a continuum of states, and the
> >probability of a serial reversal of such characters is astronomically small.
>         Except that a reversal doesn't have to go through the *entire*
> continuum (e.g. Digit I of therizinosaurs doesn't entirely reach the ankle).
> Further, if the continuum is closley correlated (as it should be to be coded
> as one character), it may be that each "subcharacter" is so intimately
> associated with the others that it is a relatively straightforward process
> to reverse each one in turn (simple example: Digit I is 75% of Digit II,
> then 50%, then 25%, then 10%).
> 
Digit I dosen't connect to the ankle in Sellosaurus or Riojasaurus
either. In Sellosaurus, Riojasaurus and Segnosaurus has a tarsal above
digit 4 and a smaller one on digit 3 and the ankle slops toward digit 1.
If the Segnosaurus ankle was found from a Late Triassic-Early Jurassic
depoist it'd have been said to belong to a prosauropod. Take a look. The
feet are almost excat! What more do is needed? Looking at the drawing of
the pes of Segnosaurus, I wouldn't be a bit surprised that the
metatarsals are drawn to far apart. What needs to be done is a good
article on the feet. 

I wouldn't be a bit surprised if some of the skeletal material from the
Lufeng actually belongs to a therizinosaur. You can bet your dollars to
donuts, that the Lufeng jaw skeleton would have 4 toes.


Tetanurae@aol.com wrote:
>
> 
> <<3)  The early Jurassic "therizino...">>
> 
> This was indeed predicted by George, but it is NOT AT ALL inconsistant with
> the idea that therizinosaurs are derived coelurosaurs.
> 
See above.
> 
> There is also the Middle Jurassic coelurosaur skull Proceratosaurs which I
> don't see anyone putting up a fuss about.
> 
That placement is debatable, but Greg may be right.

> 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. 

Not if Therizinosaurs are prosauropods, then it's not hard to believe at
all.

 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 (Stokesosaurus).

Now claim? It was orgnially clamied to be.

  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.
>
It's funny, these same people argued against a Middle to Early Jurassic
evolution to birds, but are NOW changing their minds, and who will get
the 'glory' theory for it? Not George, they'll just ignor his thory and
make their own. It's happend before and will again, why just look at
what happened to Regnosaurus...

> 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.
>
True.
 
>  <<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?  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....
> 
>  <<. . . 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 :-)  Of course, he
> can counter with, just because a lot of people agree that therizinosaurs are
> theropods doesn't mean they are :-)
> 
>  <<and I'll own up to knowing very nearly nothing about segnosaurs and
> absolutely nothing about the early J jaw.>>
> 
> I too know next to nothing about this jaw.  It seems to get Nature to western
> North America, they throw them in row boats and paddle them across the
> Atlantic, then thrown in backpacks and hiked accross the continent then thrown
> in the basement of the UW libraries for a few weeks before being put on the
> shelves...
> 
> Anyway, it is of course possible that this jaw isn't even from a
> therizinosaur.  It could belong to a prosauropod or even something like a
> heterodontosaur or a stegosaur.  I will need to read the paper (whenever it
> shows up...).
> 
Either that or it's an upside down broken maxilla...
Tracy