Re: extinction

["Dewey M. McLean" <dmclean@vt.edu>]

Dear Colleagues,

This is a follow-up to my post of Tue, 20 Jan 2004 09:49:40 on Luis 
Alvarez' misinterpretation of the K-T paleontological record that 
"proved" to him that an asteroid impact 65 million years ago killed 
most of earth's life.

Please read Alvarez' statement made in a talk at the National Academy 
of Sciences (1982), and published in the Proceedings, 1983, 80, 
627-642:

"1) that the asteroid hit, and 2) that the impact triggered the 
extinction of much of the life in the sea, are no longer debatable 
points."

In fact, the K-T transition geobiological record shows that Alvarez 
was mistaken on the magnitude of any K-T boundary impact-induced 
biological perturbation.

Cordially,
Dewey McLean

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Dear Jaime, and other Colleagues,

The general K-T transition biological turnover was underway long 
before K-T boundary time, and persisted into the Tertiary. The notion 
of a catastrophic wipe out of most of earth's life at the K-T 
boundary seems to have gotten into the literature by a physicist who 
knew nothing whatsoever about the K-T paleontological record. One has 
to be careful about imaginary "first principles" to make sure that 
they are supported by the K-T transition geobiological record--which 
is the final arbiter of all that we do in K-T science.

I recall how at the K-TEC II meeting in 1981, Luis Alvarez had looked 
at species range charts across the K-T boundary and interpreted the 
cut off of ranges of many species at the boundary as proof of an 
impact-induced catastrophe.

Paleontologists, on the other hand, know that ranges cut offs at 
specific localities are very likely are the result of a gap in the 
stratigraphic record. Alvarez simply could not understand how 
paleontologists could not see the cut off of ranges as proof of a 
global K-T boundary catastrophe.

We commonly encountered hiatus-controlled cut off of ranges at 
various places in the stratigraphic record in my graduate research 
program on Cretaceous and Tertiary marine phytoplankton along the 
Atlantic Coastal Plain.

I'll have more to say about the generalized K-T biological turnover 
in a later post.