> Mammal brain/body ratios have been increasing 
> in the Tertiary, true; I don't know if dinosaurs or birds
> exhibit(ed) the same pattern.  
This is something I have wondered about.  I don't know much about 
dinosaurs (vast understatement) but from the pictures I have seen, 
some of them appear to have been bipeds with hands.  They lived on earth 
for more than 100 million years, but never developed high intelligence.  
Why?  
Then again, maybe they did.  How would we know?  
Suppose one species of dinosaur, which I will call Dinosaurus sapiens, 
did develop high intelligence.  This happened rather suddenly, in a few 
thousand years -- a span of time too short to notice in geological terms.  
D sapiens was divided into races, only one of which discovered 
advanced science.  This advanced race of dinosaurs lived in a small 
area, which is now submerged.  Elsewhere, D sapiens were primitive 
creatures who had little interest in building permanent structures of 
stone or concrete; to the extent that they built buildings at all, they used 
wood, so there are no archeological traces of their civilization.  
Even among the advanced group, knowledge of science and technology 
was confined to an elite.  Once they discovered the basic ideas of 
mathematics and experimental science, progress was rapid.  In a few 
generations, they reached the level we have reached now, and then...  
they transcended.  
Meanwhile, however, they disturbed their ecosystem so severely that 
the other dinosaurs (and many other life forms) which did not transcend 
didn't survive.  
The question is whether it is possible to have advanced science 
without also having a world-wide industrial economy (which would 
leave traces even after 65 million years).  Given the assumption that 
this is possible (and also given the assumption that the expression  
"they transcended" has some real content), the above scenario could 
have happened.  
Lyle