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Re: Theropod "migrations"
In a message dated 4/24/99 12:38:57 PM EST, email@example.com writes:
<< So......I guess there could have been a Cretaceous Bering land bridge after
As far as I can determine, a robust Cretaceous Bering land bridge did exist
until sometime early in the Santonian, when it vanished as the sea level rose
to flood Laurasian continents with the Turgai and Kansas epicontinental seas.
At this point eastern and central Asia became isolated from other continents
and their faunas began to diverge: you will find many of the same families in
Asia and North America (whether dinosaurs, mammals, birds, or whatever), but
they evolved different genera in the Campanian and Maastrichtian when the two
regions were physically separate. When the sea level started to fall in the
late Maastrichtian, the Bering land bridge may have reappeared, so if we ever
do find late Maastrichtian faunas in Asia they may turn out to contain North
American genera and even species. The latest known Mongolian dinosaur-bearing
facies, the Nemegt Formation, is almost certainly several millions of years
older than the Lance/Hell Creek of North America, and was laid down when the
Bering land connection was still severed.