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Re: Re: Temp in Cretaceous



>So it puzzles me why the Bering Strait is said to have opened and closed so
>often to let all those dinosaurs cross over from Asia to North America and
>vice versa, if the sea level was so high. I think the Bering land bridge was
>mostly unavailable during the Late Cretaceous because of the high sea level,
>which means the Mongolian and North American dinos of that time were not as
>closely related as we might think. Same families, yes; same genera, very
>doubtful, even in the case of _Saurolophus osborni_ and _?Saurolophus
>angustirostris_. Do you know of any references documenting geological
>evidence that the Bering land bridge was open (i.e., above sea level) during
>the Mesozoic after the Campanian?
>
Of course, the configuration of NE Siberia and Alaska during the Late
Cretaceous is yet to be resolved.  Alaska, and possibly Siberia, include a
LOT of accreated terrain, so it is uncertain what the land looked like back
then.  Also, given the various orogenies going on in that region, even
today, there is no sure way (save some intensive, yet-to-be done geologic
and paleontologic field work) to establish when and where the Asia-American
connection of the Late Cretaceous was extant.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084