The idea for the dinosaur fossils at Eva's birthday party I picked up of Pinterest (I love that place).
What you'll need:
Small plastic or rubber dinosaurs - How ever many you want.
I bought a tube of 36 dinosaurs for $2.50 from Kmart
1 1/4 cup of dirt
1 1/4 cup of flour
3/4 cup of salt
A bucket to mix it all in
This mixure will make up about 8-10 dinosaur fossils, depending on the size of your dinosaurs
You need enough water to make it a clay like consistency.
Mix all ingredients
Mold the mixture around your dinosaurs
Allow to dry.
I placed them on some newspaper outside and they still took almost a week to dry completely. I kept flipping them because the moisture would gather underneath the fossils.
Then it's just a matter of hiding them, sending out a search party and once found, tapping them with a hammer to make them crumble apart.
They were such a hit that I've been trying to think of ways of interpreting them into other party themes and, as the original source suggests, they would be a fun activity to do with your preschooler 'just because'.