Here's another project I do for my "Prehistoric Art" unit my Grade 4's study with me.
It's a very simple, straightforward project that yields great results. You really can't go wrong with chalk pastel on back paper, in my opinion. Transporting them home without smudges, though, is a whole other issue!
I have a ton of dinosaur books that I collect at garage sales over the summer. Students flip through these and decide on a dinosaur to draw. On 12 x 18" black construction paper, students draw out their dinosaur and need to include some type of setting as well. They can make their dinos any colour as we really don't know what colours they were. They pass over all their pencil lines with a black wax crayon, then start colouring with chalk pastels. I encourage them to mix colours and add highlights for extra interest and realism.