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David Marjanovic wrote:
> Does someone know when exactly *Ichthyornis* and its relatives > died out?
> Did they hold on to the K-T?
So far as I know, no one has determined anything "exactly" about the
extinctions at the K/T boundary. Ichthyornis and its kin were pigeon
sized birds much like the skeletal reconstruction you mentioned at
Oceans of Kansas Paleontology (Sternberg Museum - FHSM VP-2503):
< http://www.oceansofkansas.com/Sternbrg/ichthy1.jpg >
The fact that any of them managed be be preserved in an ocean full of
big sharks, giant fish and hungry mosasaurs is pretty amazing,
especially when you consider that the chalk was deposited over two
hundred miles from the nearest shore. Even so, most of the remains that
have been found are quite fragmentary.
I suspect there were large flocks of these birds (and kin) either
feeding in mid-ocean or migrating over it. As Dan Varner indicated, the
shallowing and narrowing of the seaway towards the end of the Cretaceous
produced a higher energy marine environment.... to the point where small
fossils of anything like a bird were not as likely to be preserved.
Without some kind of fossil evidence, I don't think anyone can say that
they survived all the way to the K/T boundary, but we also cannot say
they became extinct during that those 15 million or so years after their
last known fossil remains.
I suspect that some of them were around to see whatever happened.
Mike Everhart < http://www.oceansofkansas.com >
Adjunct Curator of Paleontology
Sternberg Museum of Natural History
Fort Hays State University, Hays, KS