Of course, there are plenty of areas in the game where you'll be traveling through, but some hold different types of areas that you have to dig to get fossils in. Here are the different areas and what you'll find in each area to dig in:
The Greenhorn Plains - This area holds normal fossils as well as pay-to-dig areas where you'll have to shell out money to get the fossils that you need.
Knotwood Forest - This area holds both normal fossils and then ruins that you'll need to dig in.
Rivet Ravine - This area holds several different places where you'll have to dig. There are, of course, the regular fossils and then there are several tunnels (especiall #5 and Mole's secret tunnel), as well as area 1 and 2, and then another pay-to-dig area.
Bottomsup Bay - This area only holds regular fossils and then a pirate ship that you'll have to dig in.
The following areas hold different types of fossils and areas that are hard to pin point. So, in them we'll list them here and then give you the other locations to finding the fossils you need:
B.B. Base
Coldfeet Glacier
Dark Fossil Specials
Donation Points Fossils
Mt. Lavaflow
Parchment Desert
Secret Island
Tyrma