All it takes to create a dinosaur puppet show is some pictures of dinosaurs and some paint stirring sticks. You can create a puppet stage using some ferns or other plants to simulate a "forest" and prerecord a story that you can play for the preschoolers. The recording can include the dinosaur name, whether it was a meat or plant eater and other fun facts. You can even use a rock as a meteor to demonstrate extinction.
Anything that involves digging through dirt is going to be fun for a preschooler, and the Dino Dig game will teach them about fossils and basic archaeology. Fill paper cups about half way with sand, and then using various plastic dinosaur figures make footprint impressions in the dirt. Fill the impression with plaster of Paris and let it dry. Then fill the cup with more sand so that the footprint "fossil" is covered. Bring in the children and let them use brushes to sweep the sand away and discover the "fossil" in the sand.
It can be difficult for preschoolers to have a sense of scale when learning about the size of dinosaurs. This is a simple game that gives them an idea of how big a dinosaur was in relation to them and other items. You need to have a book that lists the lengths of the various dinosaurs and a tape measure. Roll out the tape measure the length of the dinosaur and place a piece of tape at the beginning and end. You can have a mix of large and small dinosaurs. Have each child lay down next to the tape so they can see how big they are in relation to the dinosaur.