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Re: "No Bolides!"



Nick L. writes;

>        What do people think about the Pleistocene extinctions in North 
>America? They seem comparable to the Late Cretaceous. We've lost wooly 
>mammoths, sabertooths, dire wolves, teratorns, lions, giant lions, 
>horses, ground sloths, phorusrhacids, cheetahs, rhinos, those dog-bear 
>things, and plenty of other animals.

You're comparing apples to oranges.  The difference here is that the Pleistocene
extinctions were caused by the extremely successful hunting techniques of one
predator, namely us.

>        So are we "doing well" in North America? Or are we "on the way 
>out", as many would say of Late Cretaceous dinosaurs? Dinosaurs must have 
>seen comparable lows in diversity many times, we seem to be in one now. 
>On the great plains, for example- I'm not really familiar with the 
>ecology, but if we count cougars and wolves as predators, and pronghorn, 
>bison and maybe deer as herbivores, we've got the same situation: 
>individual species doing well, number of genera low.

In the Great Plain states, the herbivores are doing relatively well, the
predator population (not counting us) is minimal.  Our species is doing
wonderfully, it's the others that are in question.

>        So even if the diversity decline is a real phenomenon, that 
>doesn't necessarily mean that it has much significance in the overall 
>extinction pattern. 

The only difference is that *we* are the force that is threatening extinction.
Ultimately, whether we are simply in a lag, or are really on the way out, seems
to be up to us to decide.

Rob

***
"Wizzo butter is absolutely indistinguisable from a dead crab."
        -MPFC