Drumheller is a town in southern Alberta in an area known as the badlands. It looks like the sort of place you'd expect to find dinosaur fossils and sure enough, there are lots of them there. Drumheller is home to the Royal Tyrrell Museum which houses Canada's largest collection of dinosaur fossils.
Quite a few post offices in Canada have special pictorial postmarks available. Canada Post occasionally updates the list of postmarks on their website but for the past few years, updates have been sparse. Over time, some of these hand stamps ware out, become damaged and even get stolen/ So it's hard to tell if a postmark you see listed on the Canada Post website is actually still in use. After comparing this recent cover from Drumheller to one I made 10 years ago, it's obvious that this postmark gets enough use to have justified a replacement. The newer postmark is larger and the fonts are different.