It's not the size of your screen but how you use it...

     My first screens were made with 1/4" hardware mesh which means you will find all but the tiniest fossils but you will also have to dig through a lot of little gravel to get to the good stuff.  Since success is measured in how often you can fill and sort a screen of gravel, the smaller mesh can eat up time.
     Initially, I was trying to figure out why the guys did so much better than me.  I was digging almost as hard so shouldn't I be calling out, "Tapir tooth!  Meg!" and so forth, just like they were?  I saw that some of them were using screens with 1/2" hardware mesh and that seemed to be the answer.  Clear out that gravel faster, get the big stuff!  In truth, fossiling success is measured in many ways with experience and luck at the top of the list, but I prefer the larger hardware mesh.  When I am sifting through so much small gravel, I get bogged down and frustrated.  I've got to keep moving!

     I run the risk of missing fossils like this beautiful molar (peccary, I think) but I clear out a lot more gravel and have more success finding a wider variety of larger fossils.

     The photo above was from one of my better days as I gained experience on the river.  From the top, a complete tapir molar with intact root, a camel tooth with intact root, a couple of serviceable megs, and to the right, my first horse teeth.  

     At this point, I digress long enough to say, I CANNOT STAND THE STUPID CAMEL TOE JOKE!  I posted a photo of a beautiful camel tooth I found and every one of my intelligent, adult friends made a stupid camel toe reference.  Believe me, I have a sense of humor, but it's time to nail the lid down on that one.

     Whew!  Glad I got that out!  

     Back to the point I was making, I know I am missing a lot of tiny shark teeth and bird bones, etc. but being new to this hobby and coming into it long after the huge mammoth leg bones and intact land tortoise shells have all been found and cleared out, I want the biggest fossils I can get!