How many genera per era?

[ArtSippo@aol.com]

It seems to me that the 850+ known dinosaur genera is a very small number 
considering the fact that dinosaurs were the dominant terrestrial life form 
for 160 million years.  I am sure this is due to serendipity in fossil 
preservation. 

Nevertheless, I was wondering how the known genera are distributed over the 
Mesozoic Era.  What percentage come from what periods?  As time went on, were 
the number of fossilized genera increasing, decreasing, or staying the same?

Dinogeorge, you may the best man to answer these questions.

Art Sippo