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Re: Thunder-Lizards



> Date: Fri, 22 Jul 2005 11:55:58 -0500
> From: Tim Williams <twilliams_alpha@hotmail.com>
> 
> "The existence of the North American genus Barosaurus in Africa is
> surprising, since terrestrial faunal exchange between Laurasia and
> Gondwana during the Late Jurassic is considered improbable due to
> marine barriers."

There is a philosophic-taxonomic issue here: should judgements like
generic separation be based on morphology alone, or also take into
account other factors such as biogeography or age difference?  I've
seen things done both ways.  Curtice (2000) writes of the Cretaceous
brachiosaurid _Sonorasaurus_, "Just because it resembles a
_Brachiosaurus_ does not it a _Brachiosaurus_ make" (sounding rather
like Yoda there :-) and recommends continued generic separation of
these morphologically identical taxa on age grounds alone.

> This could also undermine the notion that _Brachiosaurus altithorax_
> (Morrison) and _Brachiosaurus brancai_ (Tendaguru) belong in the
> same genus.
>   And I know how much Mike loves the name "Giraffatitan"!  :-)

Grrr!  :-)

Having recently seen both the _B. brancai_ and _B altithorax_ type
material, I think there is plenty to tie them together.  But I will
say no more on that subject for the time being (not least because I
need to see some basal titanosaur vertebrae before committing myself.)

>> "_Gigantosaurus_" _robustus_ = _Janenschia robusta_ =?
>> _Tendaguria_.
> 
> [...] I think you're right on the money when you suggest that
> _Janenschia_ and _Tendaguria_ might be the same after all.

Just to be clear, I am not "suggesting" this, just mentioned it
because it's been suggested in print.  Since I've not seen either the
_J._ or _T._ material, nor even read the _T._ paper, I'm not in a
position to have an opinion one way or the other.  However --

> The dorsals of _Tendaguria_ are certainly very weird

This much I certainly do agree with!  :-)

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor  <mike@miketaylor.org.uk>  http://www.miketaylor.org.uk
)_v__/\  Archosaurs rule!

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