Press gently into the plaster and let set until dry. Cover exposed side of dinosaur with petroleum jelly. Put two more inches of plaster on top of the bottom layer. Use a chisel and hammer and gently tap on the seam. When the mold breaks, there will be a fossil of the dinosaur.
Dinosaurs Are Different.
Thomas Y. Crowell. Holiday house, Inc. 5. Morrow Junior Books. Dinosaurs Walked Here. Harper Collins Publishers.