Fwd: Re: Remember the Alamosaurus (was RE: taxonomy is not stratigraphy)

[Tim Donovan <uwrk2@yahoo.com>]

--- "Jonathan R. Wagner"
<jonathan.r.wagner@mail.utexas.edu> wrote:

> At 06:59 AM 8/3/2005, Tim Donovan wrote:
> >   That makes sense. IIRC TMM 41436-1 was found low
> in
> >the Javelina, and therefore at least 69 Ma old,
> well
> >before the Lancian.
> 
> Actually, Lawson writes that the maxilla was found
> in the "lower third of 
> the Tornillo Group." Confusion on this matter is
> certainly warranted, as 
> Scheibout et al. suggested that the Tornillo Group
> should be lowered to 
> Formation. However, the lower third of the Tornillo
> Group IS the Javelina 
> Formation. The precise stratigraphic level of the
> specimen will be revised 
> based on a new section measured right up through the
> locality by Tom 
> Lehman. I cannot recall exactly how high the
> specimen is, but I seem to 
> recall it is close to the K/T boundary, i.e., NOT
> Edmontonian.
> 
> 
> 
> > > 3) There is no evidence from the Javelina
> Formation
> > > that tyrannosaurids
> > > fed on sauropods.
> >
> >   Considering the small size of the specimen
> compared
> >to T. rex, that isn't surprising. Alamosaurus was
> too
> >big to overcome, except for juveniles. Maybe that
> was
> >why Alamosaurus was so common in the Javelina but
> not
> >in the units where T. rex apparently is known, the
> >McRae and North Horn.
> 
> Were you assuming a T. rex could take out an
> Alamosaurus? ;)
> 
> I kind-of doubt tyrannosaurs were the major control
> on sauropod abundance, 
> but I suppose stranger things have happened. One
> alternative to consider: 
> the abundance of sauropods may be facies-dependent
> (at least, where it 
> occurs). There is some evidence to support this.
> 
> Jon
> 
> 
> 


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