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Re: [dinosaur] When did T. rex evolve?

It is not certain. For one thing, the age of the lower boundary of the Hell Creek is not as securely dated as the upper. Secondly, the stratigraphic level of many of the classic specimens are not firmly placed in the context of Hell Creek stratigraphy.

That said, it is probably not older than 67.4

On Mon, Sep 18, 2017 at 4:38 AM, Poekilopleuron <dinosaurtom2015@seznam.cz> wrote:
Good day,

I would like to ask, what is the most exact geologic age setting for _Tyrannosaurus rex_? Lower limit would be 66.0 mya of course, but what about its earliest fossil remains? One study gave age of some 67.4 mya, but is that generally agreed upon? Thank you in advance, Tom


Thomas R. Holtz, Jr.
Email: tholtz@umd.edu         Phone: 301-405-4084
Principal Lecturer, Vertebrate Paleontology

Office: Geology 4106, 8000 Regents Dr., College Park MD 20742

Dept. of Geology, University of Maryland

Phone: 301-405-6965
Fax: 301-314-9661              

Faculty Director, Science & Global Change Program, College Park Scholars

Office: Centreville 1216, 4243 Valley Dr., College Park MD 20742
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
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