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Re: Dino extinction



> 
> This is a little counterpoint to the DINO-Fest presentation:
> "What the Fossil Record of Dinosaurs Tells Us"
> By Peter Dodson (University of Pennsylvania)      
> 
> What does the fossil record say about dinosaur extinction? 
> -------------------------------------------------------------
> The K/T boundary is defined by a very thin boundary clay enriched 
> in Ir/siderophiles typical of an extraterrestrial body. Dino fossils
> worldwide occur up to this boundary layer, then the density of dino
> fossils drops to nothing, zilch, nada. Approximately half of the genera
> of other living organisms of that time exhibit a similar pattern in
> the fossil record around this K/T boundary clay. I'm not sure how much
> clearer the fossil record can say "CATASTROPHE OCCURRED HERE". 

Sure, maybe a catastophe. Did it cause the extinction? Were not even sure
it was a extraterrestrial body. We don't even have a good crater site that
can be proved. The only thing we have is some trace element around the
world the time dinosaurs died out. Now, prove to me that they didn't die
out a thousand years before the "meteor" hit. Or even that there was one
at all. We need to prove cause and effect.

> 65 million years ago. Furthermore, a large(>200 km) impact structure 
> has been identified at Chicxulub, Mexico that dates to exactly 65 million
> years ago. This crater is probably the smoking gun to the K/T catastrophe.

There is increasing doubt that it is an impact site at all. 
 
> Fossil remains of dinosaurs occur worldwide in deposits from the 
> Triassic until the end of the Cretaceous. The density of fossils 
> varies greatly throughout the column. I'm very skeptical regarding 
> claims that the dinos were "dying out" before the end of the Cretaceous. 

The variety of dinosaur species thinned out a great deal before the
extinction. 

Also, someone out there clarify for me; my foggy head
remembers hearing that people just didn't look too hard for dinosaur
fossils after the K/T, and just now the scienctist have started looking for
them. Anyone know what I'm talking about?


> The real coup de grace of the dinos correlates all to well with the 
> K/T boundary(and associated bolide impact) to be merely a coincidence. 

Science is based on facts and research, not "this can't be a coincidence".

The only problem I have of this theory is it has been popuarized as
trumpeted as a fact and not a theory. I really see no compelling evidence
to put together a cause-effect realtionship. Dr. Dodson who I know
personally is a very cautious and careful scientist as well as one of the
world's best dino paleos. If there was evidence, he would except it. I
think we need to find out why dinos died out, not defending some easy
answer pet theory. 


-Sherry