Dinosaurs Are Dragons

This is a good example of a trope that appears to be changing from one thing to another. Basically, some people just can't get over how similar some dinosaurs are to dragons.

Dinosaur Doggie Bone

Uh-oh. There's a dog loose at the natural history museum! The museum is full of priceless fossilized dinosaur skeletons, worth millions upon millions of dollars. And we all know what dogs like to munch on, don't we? Prepare to see the little pooch walk out the door with a jumbo-sized femur in his mouth, and to hear the sound of many bones collapsing into a pile in the background.

Everything's Better With Dinosaurs

Well, it's true. Dinosaurs are cool. No exceptions.

Since dinosaurs actually existed in the past, some writers like to throw them into their stories. In many cases, this makes no sense at all, but when dinosaurs show up, we're generally in the realm of awesome for the sake of awesome. Generally, the dinosaurs seen will be restricted to a few well-known types.

Lost World

They are usually found in remote locations, such as the center of large and barely explored continents (usually Africa), the polar ice caps, or mysterious islands. They are often home to lost civilizations with amazing Lost Technology, or to prehistoric animals that have managed to survive unchanged - aside from the fact that they suddenly find humans delicious.

See also: Lost Worlds of Dinosauria: A visual survey

Phlebotinum Killed The Dinosaurs

While writing a story, an author needs a way to show how bad things would get if the Big Bad took control or the Applied Phlebotinum blew up. So the author attributes some historical disaster to their plot. And what's the biggest disaster one can imagine?

Prehistoria

The hollywood version of the stone age, where cavemen and women and dinosaurs live side by side. Most of the time, the dinosaurs will live in volcanoes and/or breathe fire. Expect the landscape to be dotted with jungle and lava pits (or perhaps tar pits). You might also have a mix of different prehistoric creatures — like mastodons and triceratops living side by side. Music will usually involve lots of percussion, and, if you listen very carefully, the soft sobs of a palaeontologist.

Somewhere A Palaeontologist Is Crying

In real life, a wide variety of dinosaurs walked the Earth over a period of about 180 million years. Most of them evolved from other dinosaurs and, naturally, when a given dinosaur was walking around, its ancestors were most likely extinct. Also, just like modern animals, different dinosaurs lived in different areas and habitats.

However, most writers don't realise this.

Stock Dinosaurs

As just about any six-year-old will eagerly tell you, dinosaurs are awesome. And from Hollywood's point of view, they make for great, epic beasts and terrifying monsters, particularly given the fact that they actually existed at one point. Hence, it's only natural that writers would want to include dinosaurs in their stories.

Unfortunately, most writers only know a few types of dinosaur...

Slurpasaur

Making movies about giant monsters (often dinosaurs) is downright awesome. However, sometimes, the filmmakers just don't have the budget to make a somewhat convincing monster suit or an animatronic puppet or even a crappily animated CGI monster.

But, all hope is not lost. No.... you can just take an ordinary lizard, alligator or other non-extinct reptile, tape a few cardboard fins and horns, and... ta-da! Instant dinosaur!