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Re: Tyrant stuff (no longer ranting) (was RE: Rant (was RE: Details on SVP 20...




From: "Andrew A. Farke" <andyfarke@hotmail.com>
Reply-To: andyfarke@hotmail.com
To: <dinosaur@usc.edu>
Subject: Re: Tyrant stuff (no longer ranting) (was RE: Rant (was RE: Details on SVP 20...
Date: Sat, 9 Nov 2002 13:39:15 -0700


> If it was so easy to get across, why are there no ceratopine or
> centrosaurine ceratopians in Asia (for example)? Easy for one means easy
for
> all.

I'm undecided on the on-list land bridge discussion, but I will throw in the
point that just because a land bridge exists doesn't mean that a species
will necessarily utilize it. If a species does utilize it, this doesn't mean
that it will become firmly established (and hence fossilized). Habitat
differences between the two continents may have rendered it difficult for
ceratopsids to become established in Asia

This is the best explanation IMHO. Note that taxa which successfully emigrated were broad snouted e.g. ankylosaurids, hadrosaurs, whereas narrow snouted, more selective feeders such as nodosaurs and big ceratopsids may not have found enough of their preferred vegetation to survive in Asia, where the climate was generally more arid.




(or at least the areas of Asia for
which we have fossiliferous strata). I make this statement with the caveat
that it's pure speculation. The fossil record for Asia *is* pretty patchy.

It is true that known LK Asian environments were well inland but some ceratopsids lived in intermontane basins e.g. Torosaurus, so their absence in Asia seems real.





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