Digging for dinosaur bones makes a great kids' party activity. Or, perhaps you want to hang simulated fossils in a wall display. Most dinosaurs were not the gigantic "terrible lizards" like Tyrannosaurus rex or stegosaurus. A great many prehistoric beasts were actually quite small, the size of a chicken or a turkey. You can simulate these fossils very easily with readily available materials.
Find a reference illustration of a fossil skeleton. Books such "Introduction to the Study of Dinosaurs" by Anthony J. Martin are a very good source. The archaeopteryx (a Jurassic-era bird), saltopus ("leaping foot" in Latin) and lesothosaurus ("Lesotho lizard") are all about chicken-sized.
Boil chicken bones for an hour or more, or until all the meat has boiled off.
Separate the bones carefully so that you are left with loose parts.
Soak the bones for two hours or more in a half-and-half solution of vinegar and water. This will completely remove the meat and prevent rotting. Set aside to dry.
Mix white plaster with vermiculite, the mineral used in gardening. This will simulate microscopic fossils found among dinosaur bones.
With the plaster still wet, press the chicken bones into the plaster, arranged like your reference picture.
Allow to dry, or bake in the oven per plaster manufacturer's instructions.
Mix brown paint into some lacquer until the lacquer is still fairly transparent, but is darkened. (You may just spray the surface of a cup of lacquer with brown spray paint.)
Brush the paint/lacquer mixture lightly over your fossil and allow to dry. It should look like an authentic dug-from-the-earth fossil.
Find a reference tooth to model. Most dinosaur teeth curved from front to back, allowing the creature to grab its prey. Shark teeth were more triangular, like the shape of a spade head.
Mold white air-drying clay into the shape of the tooth.
Scrape a few lines, lengthwise, into the tooth while the clay is still soft. Most fossil teeth have some lines like these.
Bake the clay to hardness, if the manufacturer's instructions allow. Let it cool.
Chip away at the base of the hardened tooth with a small hammer or rock. This will simulate where the tooth broke off, perhaps in battle.
Spray the tooth lightly, first with some black spray paint, then some brown. Repeat until the tooth is well coloured and allow to dry.
Spray or brush the tooth lightly with lacquer. Fossilised teeth are usually better preserved than bones as they are less porous. The resulting fossil can be quite smooth.