Re: Selective Extinction

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

Betty Cunningham writes,

>birds, of course, survived, whereas pterasauroids did not so if you can
>perhaps explain why?
>Wehn Mt. St. Helens went off, birds that flew away survived, but still
>had to deal with the ash that covered everything afterwards to search
>for food and water.

When we look at the major theories for the late-K mass extinction, all of them 
point to a heavily restrictive environment.  To use the haymaker-impact 
scenario as an example, the resulting disruption of the land food chain will 
mean that food will be in short supply.  Because of this, animals that can get 
by on small amounts of food will survive, which would include most ectotherms 
and smaller endotherms.  Under this hypothesis, birds survived because they 
enhabited the "small endotherm" end of the scale, while the pterosaurs were in 
the "large endotherm" end.

So, IMHO, birds survived simply because they were small.


Shalom,

Rob Meyerson

***
Black holes are where God divided by zero.