Re: Extinction

[Dinogeorge@aol.com]

In a message dated 3/23/00 1:02:17 PM EST, jbois@umd5.umd.edu writes:

<< So it is this gag rule I am protesting, a style of argument which
 prohibits certain kinds of evidence--or certain hypotheses, because they
 challenge your own ideas. >>

Most of the so-called "evidence" you have brought into the discussion is of 
an extremely dubious and controversial nature with practically no support in 
the fossil record. Neornithan birds outcompeting enantiornithan birds? Avian 
fossils from near the K-T boundary are virtually nonexistent, yet you want to 
discuss detailed ecological scenarios of bird evolution and extinction during 
that period? Come on!

The bolide impact happened at exactly (to within every determinable error 
margin) the time when there was a massive faunal/floral turnover and 
extinction across a wide variety of habitats and taxa, including 
microorganisms, plants, invertebrates, and vertebrates. A global extinction 
such as that observed at the K-T boundary requires a global cause; it cannot 
be the result of a coincidence of a multitude of individual lesser local 
extinctions--one kind of bird outcompeting another kind of bird at just the 
same time that, say, sauropods in South America succumb to some kind of 
disease and, say, European ornithopods are terminally devastated by mammals 
eating their eggs and, say, volcanism wipes out the abelisaurs in India. The 
evidence for a bolide impact is overwhelming; we have the crater, we have 
boulder fields scattered as much as 1000 km from the impact site, we have a 
>worldwide< boundary clay layer with tell-tale extraterrestrial 
chemical/isotope signatures. This is the kind of global event required to 
produce a mass extinction. When you have a corpse lying in a pool of blood on 
the floor with a smoking pistol nearby, your working hypothesis should not be 
"death from cirrhosis of the liver."