Plastic dinosaurs are made from real plastic. Plastic dinosaurs are not made from dinosaurs, this is a common misconception made very popular on the internet. Plastic made from oil is also another popular misconception.
If you look at it that way, that petroleum is considered to be "fossil fuel," and that plastic is made in part by "fossil fuel"... Sure, why not..? Plastic dinosaurs are made from real dinosaurs... well... plastic is made with some sort of fossils, anyway. Your plastic brontosaurus might be made from pieces of ancient plants, bones, and who-knows-what-all... Are Fossil watches made from real fossils..? 8)