We will be studying dinosaurs later in the school year but now is the time I buy 'dinosaur bones'. Halloween skeletons make great dinosaur bones for our preschool paleontologists to dig. You can buy now or wait for the post-Halloween sales. You will just need the arm and leg bones. You can use the remaining bones (skull, ribs, hands, feet) for Halloween decorations.
http://metamoracommunityprek.blogspot.com/2011/01/dinosaur-dig.html
Need more ideas for dress-ups and dramatic play? More ideas are listed under the 'Dramatic Play' label.