Weishampel et al.'s Formation Dates in The Dinosauria

[Saint Abyssal <saint_abyssal@yahoo.com>]

I have been using Weishampel et al.'s "The Dinosauria" as a reference for my 
Wikipedia editing for some time now, especially in articles relating to 
geologic formations. Sadly, I just noticed last night that when there are 
dinosaur-producing outcrops from a given formation in more than one state, 
Weishampel only gives the age of the particular outcrop then being discussed. I 
had been under the impression he was listing the age of the whole formation.

Now I have concerns about the accuracy of some of my contributions and about 
using The Dinosauria as a reference for the ages of geologic formations. I was 
hoping some of you could give me advice: 

Would taking the oldest age and the youngest age given by Weishampel et al. be 
a reliable way to determine the start and end dates that the formation was 
deposited? 

What if there are outcrops of the formation outside that age range that are 
unlisted because they haven't produced dinosaur fossils? 

Is there a relatively comprehensive and trustworthy guide to the ages of 
geologic formations online that I can use as an alternative, or should I stick 
to The Dinosauria?

~Abyssal