Re: sauropod quantity

[Josh Smith <smithjb@sas.upenn.edu>]

Dinogeorge@aol.com wrote:

> In a message dated 9/18/99 10:52:56 AM EST, sarima@ix.netcom.com writes:
>
> << Not merely possible, virtually certain.  Almost any model of taphonomic
>  processes shows a relative impoverishment of small, delicate forms. >>
>
> There are thousands and thousands of footprints of small chicken-size to even
> sparrow-size(!) dinosaurs known from the Triassic and Jurassic, yet not one
> good bone specimen of any such form has ever been identified. Martin Lockley
> and Paul Olsen and probably others (Ellenberger) have noted these in several
> publications; see, e.g., The Eternal Trail by Lockley. The larger dinosaurs
> we know from skeletal material are like the visible tip of an iceberg.

    Where is this coming from, George?  First of all, if we are talking truly
"chicken-sized" and "sparrow-sized" in the  Triassic and Jurassic, then we are
talking about the Norian to the, say Toarcian, ja?  If these are the ages we are
discussing, then there are not "thousands and thousands" of tracks in this size
class.  Indeed, these tracks are biased towards the mid-range (from about 4-8
inches in track-length).  If we discuss only the Newark Supergroup ichnofauna,
then I would doubt that there are more than a couple hundred such tracks.
     Second, there most certainly are good representative specimens of small,
dinosaurs that are potential trackmakers for these tracks.  _Coelophysis_ comes
immediately to mind.  True, there are not  MANY of such specimens and we
particularly want for pedal material, but to say that not one good bone specimen
that fits this description is not being true to either the literature or the
collections.  There is actually a good deal of bone from these deposits, and
Paul is one of the strongest supporters of that statement.
    Third, the point that sarima@ix.netcom.com made about almost all taphonomic
modes favoring larger material is incorrect.  Virtually all lacustrine
taphonomic modes and most marine ones (which together far outweigh the
terrestrial fluvial realm in terms of outcrop area) are, if anything, biased
towards  smaller material.

Cheers,
the tooth guy

--
Josh Smith
Department of Earth and Environmental Science
University of Pennsylvania
471 Hayden Hall
240 South 33rd Street
Philadelphia, PA  19104-6316
(215) 898-5630 (Office)
(215) 898-0964 (FAX)