Re: taxonomy is not stratigraphy (was Re: JVP 25(2): New Dinos, Birds, Discoveries)

[Tim Donovan <uwrk2@yahoo.com>]

--- Tim Williams <twilliams_alpha@hotmail.com> wrote:

> Tim Donovan wrote:
> 
> >P. Currie mentioned healed bite marks on sauropod
> bone from the Morrison, 
> >IIRC, suggesting that even early theropods attacked
> sauropods capable of 
> >defending themselves.
> 
> Well, I'm not suggesing that the predator had a 100%
> success rate.  Even 
> weak and sick prey manage to escape sometimes.

  Maybe not often enough to be represented in the
fossil record. :)


> 
> >  Giganotosaurus and Argentinosaurus,
> >Carcharodontosaurus and Paralititan,
> >Torvosaurus/Epanterias and Brachiosaurus etc.
> Starkov mentioned other 
> >examples.
> 
> This reprises some of what Denver said: just because
> a given habitat 
> includes both a very lage predator and a very large
> herbivore does not 
> necessarily means that the former specifically
> targeted the latter.  
> Medium-sized predators may have sought prey larger
> or close to the size of 
> themselves (e.g., _Velociraptor_ vs _Protoceratops_;
> _Deinonychus_ vs 
> _Tenontosaurus_, maybe).  Large predators may have
> sought prey much smaller 
> than themselves.  


  Certainly not invariably in the case of
tyrannosaurs. There are healed bite marks on
Triceratops, ankylosaur and hadrosaur bone.


>There is a chapter in the new
> _Carnivorous Dinosaurs_ 
> volume dedicated to this issue.  I think Starkov's
> one-on-one predator-prey 
> match-ups are too simplistic.
> 
> >  Yes, but Tarbosaurus was smaller than T. rex,
> 
> Not by much (if at all).


 See the illustrations in The Complete T. rex. Even
PIN 551-1 had a skull only 1.35m long vs 1.5m for T.
rex. UCMP 118742 and a more recently discovered
specimen may have been even larger.


> 
> >Based on that, and the Tyrannosaurus-like TMM
> 41436-1 in a titanosaur 
> >dominated mid Maastrichtian environment, it appears
> that Starkov is right 
> >about the origin of T. rex. Like
> >previous theropod giants, it apparently arose in
> response to large 
> >sauropods.
> 
> Or vice versa.

  I doubt it. Sauropods were already present in NA by
the late Campanian, well before T. rex or its closest
relatives.



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