Re: Fastovsky vs Archibald

[TooTs <DragonsClaw@gmx.net>]

>It's not a sin to extrapolate
> time boundaries over extremely short distances, but it should be noted in
> the paper if it was done.  However, extrapolating time boundaries over
> longer distances is *not* a good thing.

Hello everyone!
I would like to ask a question concerning this:
Dromaeosaurus albertensis for example is "timed" late Campanian - late
Maastrichtian. Would that allow to infer that dromaeosaurids were around
until the end of the Mesozoic? Or would it be more "safe" to say something
in the way of "it is likely that they were around until the end of the
Mesozoic"?

Thanks in advance!

----- Original Message -----
From: "Phil Bigelow" <bigelowp@juno.com>
To: <dinosaur@usc.edu>
Sent: Monday, June 20, 2005 2:14 PM
Subject: Re: Fastovsky vs Archibald


>
>
> On Mon, 20 Jun 2005 09:16:09 -0700 (PDT) Tim Donovan <uwrk2@yahoo.com>
> writes:
>
> > The discovery of
> > "Aublysodon" remains at the K-T suggests T. rex
> > survived to the end too, wouldn't you say? :)
>
>
> Well, it depends.
>
> 1) Are the remains single elements or are they articulated? (single
> elements may suggest older reworked material).
>
> 2) What is the depositional environment where the remains were found (if
> the fossil is a single element, then channel sandstone or point bar
> deposits suggest older reworked material).
>
> 3) Is the iridium layer ACTUALLY near the site of the remains (in other
> words, was the presumed boundary layer actually tested for iridium?; if
> it contains iridium, can the layer be easily traced to a point directly
> above the remains?).  Dirty little secret:  a lot of so-called "boundary
> beds" in the Hell Creek Fm., are actually INTERPRETED to be there.  The
> iridium layer is in reality a discontinuous layer (due to paleoerosion),
> and workers sometimes do extrapolation.  It's not a sin to extrapolate
> time boundaries over extremely short distances, but it should be noted in
> the paper if it was done.  However, extrapolating time boundaries over
> longer distances is *not* a good thing.
>
> 4) How far below the confirmed Ir-containing boundary layer are the
> remains?  In the Hell Creek Fm., a one-meter stratigraphic separation may
> represent a time span of only one year OR it may represent a time span of
> 10,000 years.  It all depends on #2 (above).  So, does making it to
> within one meter of the K-T boundary mean that the taxon was present when
> the big rock fell?  Not necessarily.
>
> 5) Is the material properly taxonomically identified?  In the case of
> _"Aublysodon"_, that is problematic.  It would be more scientifically
> accurate to publish the occurrence as Tyrannosauridae indet., rather than
> as a genus (that is currently in dispute).
>
>
> > But what
> > about Edmontonia?
>
>
> The same rules apply.
>
> <pb>
> --
>
>
>