Re: Theories on the extinction of dinosaurs

[John Bois <jbois@umd5.umd.edu>]

On Sat, 20 Nov 1999 Dinogeorge@aol.com wrote:

> Science that has the Sereno et al sauropod article also has a feature [p. 
> 1281] on the extinction and the incidence of dinosaur fossils below and above 
> the clay: at a mere 1.8 meters below the clay is the last known dinosaur, 
> represented by a Triceratops bone; above the clay, zilch dinosaurian--the 
> workers found >no< gradual extinction). The question of >why< it happened to 
> be fully sufficient at that time is a different question peripherally related 
> to the extinction. 

Does this refer to the Lillegraven and Eberle paper?  If so, I disagree
with your conclusion.  So many coincidences seemed to have occurred at
this time, I think you have biased one over the others.  For example, as
noted in the L and E paper, there was an important immigration of mammals
"just at the time" non-avian dinosaurs became extinct.  On the other hand,
L and E report no evidence of iridium (I don't know if they tested).  So,
evidence of new mammals (admitedly, only conylarths), no evidence of
impact.  Additionally, there is zero evidence that _any_ impact _ever_
caused _any_ extinctions, direct evidence, I mean.  Mammals are proven
enemies of large flightless birds.  Surely they have earned the right to
be considered a prime suspect.