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RE: Age Abstractions

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]On Behalf Of
> franklin e. bliss
> Reworking of stuff is pretty common though. Articulated specimens are
> the only proof beyond a doubt.

Actually, I would put footprints in that category, and nests/undamaged eggs.

> Besides, I suspect that several non-avian theropod types did survive
> what ever punctuated event that killed the majority of dinosaurian
> types.  They lingered on in a new habitat with different ecological
> niches and new food chain relationships until they weren't viable as
> a population any more.  Then they followed their ancestors to the
> grave as a species.  Mammals jumped in and filled the void.  I would
> be very surprised if several dinosaurian lineages don't eventually
> pop up in Paleocene rocks lasting a few to hundreds of few thousand
> years after the K/T boundary.


>  It all boils down into where is that
> durned boundary.

Incidentally, technically the base of chronostratigraphic units are defined, 
with the top "defined" only by the base of the
overlying unit one. So **technically** the Danian, Paleocene, Paleogene, and 
Cenozoic don't properly begin until the base of the
boundary clay at El Kef, Tunisia (http://www.stratigraphy.org/danian.htm) and 
correlated over to North America by such means as the
iridium spike, FADs and LADs of index species, etc.

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796