Whenever there's a Lost World with dinosaurs or other prehistoric animals that survived extinction to modern times, there's a good chance that despite being around for millions of years, they will be virtually unchanged by evolution, existing in the same species and genera as they did in prehistoric times. Can be Truth In Television since the Trope Namer is a term used to describe modern-day animals that have changed little from their fossil versions. Examples:
- Dinotopia: All prehistoric animals are the same as they were millions of years ago, except that they're sentient. This was a conscious choice by James Gurney.
- King Kong's Skull Island has (antiquated dinosaurs living in it, all of them unchanged from their prehistoric ancestors. The 2005 remake notably averts this trope, featuring "evolved" versions of prehistoric dinosaurs.
- Despite being cloned directly from prehistoric dino blood, the dinosaurs in Jurassic Park actually avert this, since genetic modifications were made to their DNA.
- The Valley Of Gwangi has an ancient Allosaurus, Styracosaurus and Pteranodon.
- A literal version would be prehistoric Pokemon.
- In the main game series at least "fossil" Pokemon are extinct in the region you find their fossils in, which double as the only way to actually catch those Mons. In other regions (anime and spinoffs), they are indeed alive and well.
- Relicanth is based off of an animal called the Coelacanth, which has also survived for millions of years with very minimal change.
- Ice Age: Dawn of the Dinosaurs is an example of this trope, because even though it takes place a long time ago, it still takes place in an era where dinosaurs were supposedly extinct.
- Many Real Life Living Fossils include triops, horseshoe crabs, sharks, crocodiles, and the infamous coelocanth. It should be noted, though, that this isn't a particularly accurate term for them, since these animals, while superficially unchanged, are genetically distinct from their ancestors.
- Arthur Conan Doyle's much-imitated The Lost World featured a isolated plateau in the Amazon where dinosaurs and cavemen still exist.
- The GEICO Cavemen are cavemen living in the modern world. They get offended at the GEICO commericals saying "so easy, even a caveman could do it."
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