Re: (fwd) Re: Mammals as a cause of Dinosaur extinction

[rjmeyer@ix.netcom.com (Rob Meyerson)]

>1. The first placental (I repeat placental, placental, placental)
>mammals
>are from 85-90 mya. Is it coincidence that the decline in the number
>of
>dinosaur species began about that time? It sounds suspicious to me.

I would call this coincidence.  Take a look at your typical placental from that 
time.  It did not have the jaws to become any serious threat for young 
dinosaurs.  Actually, placental development seems to make more sense as a 
defence from dinosaurs like Troodon who actively hunted them.

>2. In all probability some meteor struck the Earth 65 mya and had
>climatic
>effects. From what I had read, the dinosaur record ceases some 100,000
>years
>before the KT boundary.

Be careful.  The above is based on negative evidence. What happens when a 
dinosaur is found at the K-T boundary?  Also, there were climatic changes 
worldwide, due to continental uplift.  This was more likely due to the decline. 
 Check out the history of the SD Badlands for a mammalian example.

As far as the rest of your points are concerned, they are refuted by a question 
of size.  For two species to be in competition with each other, they must be 
relatively close in size.  What the "Dino-killing Mammal" hypothesis does is 
pit a hamster against _Tyrannosaurus rex_.  Unless this is a scene out of Monty 
Python (The Ant Hunting the Timber Wolf, for example), I'm putting my money 
with the Rex.

The only that the mammals would have been any threat to the dinos would be if 
they were the carriers of Bakker's Killer Virus; this would be difficult to 
prove with any certanty.


Shalom,

Rob Meyerson

***
Early bird gets the worm, but the second mouse gets the cheese.