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RE: well-lit dinosaurs



From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of Gavin Rymill
>
>This is only tenuously a list topic but the BBC website still managed to make it a dinosaur headline!!
>
>
>Still interesting though.
>
Cool stuff.  Apparently preliminary data suggests that the Earth's magnetic field during the Long Cretaceous Normal (C34n, running from the lower Aptian (c. 120 Ma) to the beginning of the Campanian (c. 83.5 Ma)) was three times the present intensity.
 
This mid-Cretaceous is an interesting time for a number of (quite possibly interrelated) reasons:
 
*Highest sea levels since the Cambrian (at least), making it the highest in post-Pangaean history
*Higher activities of the mid-ocean ridges
*Faster rates of sea-floor spreading
*Extremely low temperature gradient from equator-to-pole (that is, climate at the equator and climate at the poles were very similar, and hot)
*Greater total separation of landmasses than at present, due to the net effects of plate tectonics and oceanic highstands
*REALLY big South American and African dinosaurs
*Fins, fins, fins, fins...
*Arrival of Asian-style dinosaurs into the Western Interior of North America (latest Albian/earliest Cenomanian)

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742      
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796