[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: mammals over dinosaurs in continuous sequence



Message text written by INTERNET:Dinogeorge@aol.com
>All these responses are very interesting, but the question being addressed
is 
where in the world is there a K-T boundary sequence with dinosaur fossils 
below the boundary and no dinosaur fossils, only mammals, above it.<

There's a site just west of Denver (in Golden, actually) called South Table
Mesa which is approximately 2/3 Late Cretaceous Denver Formation and 1/3
(at the top) Early Paleocene Denver Formation.  Both sections have produced
fossils, dinosaurs below (the type of _Ornithomimus velox_ was found in the
same formation very nearby; I'm not sure about mammals in the Cretaceous
part), and a nice partial skull of _Baioconodon denverensis_ as well as
plant fossils above.  Oddly, last I heard, no one had found iridium on the
mesa, and the precise location (stratigraphically speaking) of the boundary
is unknown.  However, the presence throughout the formation of dated
volcanic ashes demonstrates that the boundary is in there, somewhere... 
Anyone who's been to Dinosaur Ridge and seen the footprints in the Dakota
there have inevitably looked north and seen the mesa.

                _,_
           ____/_\,)                    ..  _   
--____-===(  _\/                         \\/ \-----_---__
           /\  '                        ^__/>/\____\--------
__________/__\_ ____________________________.//__.//_________

                     Jerry D. Harris
                 Fossil Preparation Lab
          New Mexico Museum of Natural History
                   1801 Mountain Rd NW
               Albuquerque  NM  87104-1375
                 Phone:  (505) 899-2809
                  Fax: ; (505) 841-2866
               102354.2222@compuserve.com