First appearance: Ghost of Slumber Mountain
Author/Creator: Willis O'Brien
Media: Film
Year: 1918
Located: Peak of Slumber Mountain at the edge of the Valley of Dreams
Plot/Premise: The spirit of the mountain hermit Mad Dick provides tale-spinner Uncle Jack with a time-viewing telescope. Through this Jack is able to see dinosaurs eating and fighting among themselves.

First appearance: Cesta do praveku (Trip into Prehistory), Viaje a la Prehistoria
Author/Creator: Karel Zeman
Media: Film
Year: 1955
Located: Transtemporal landscape
Plot/Premise: The "river of time" is entered via a cave, and a tunnel that opens out onto a river. As a traveler slips downstream they find they are traveling farther back in time on a "river of evolution". Travelers eventually meet dinosaurs and pterosaurs until being finally forced to cross a Carboniferous swampland infested by amphibians and insects until they reach an endless ocean where life began.
Adaptations: Dubbed and released as Journey to the Beginning of Time.

First appearance: "Land of the Lost"
Author/Creator: Sid and Marty Krofft
Media: TV series
Year: 1974
Located: Pocket universe

Plot/Premise: The Land of the Lost is a very small, closed pocket universe that consists of a valley surrounded by mountains. A traveler attempting to pass over the mountains will find himself reentering the valley from the other side; at one point the Marshalls climb a mountain peak and using binoculars are able to see far enough across the valley to observe themselves from behind. There is one major river flowing through the Land, forming a similarly closed loop; it flows into a cave at one end of the valley and comes out as a waterfall at the other end.

Sequels/Other appearances: "Land of the Lost" (TV series, 1991), Land of the Lost (Film, 2009)
Adaptations: "Valley of the Dinosaurs" (a Hanna-Barbera cartoon with a virtually identical premise)

Plot/Premise: Skartaris is essentially a translation of Edgar Rice Burroughs' Pellucidar into the graphic medium, with elements of Jules Verne and half a dozen other fictional Hollow Earth settings, and the admixture of magic and the Atlantis myth. In Grell's concept, as in Burroughs', the Earth is a hollow shell with Skartaris as the internal surface of that shell. Skartaris is accessible to the surface world via a polar opening allowing passage between the inner and outer worlds. There are also various tunnels connecting the interior world with the surface. Skartaris is lit by a miniature sun suspended at the center of the hollow sphere, so it is perpetually overhead wherever one is in Skartaris. Skartaris is overrun by a variety of prehistoric creatures from all geological eras, notably dinosaurs. Jules Verne's adventurers made their Journey to the Center of the Earth. Skartaris was retconned into being Another Dimension. It cannot actually exist within the DC Universe's Earth, which isn't hollow.
Sequels/Other appearances: Suicide Squad: Raise the Flag (2007); "The Land of Summer's Twilight" (The Books of Magic issue #3)
Adaptations: "Battle at the Earth's Core" (Super Friends, TV animation, 1973); "Chaos at the Earth's Core" (Justice League Unlimited, TV animation, 2004)

Plot/Premise: This unnamed lost world is accessed via a powerful transdimensional vortex found surrounding the Bermuda Islands and which has become known as the Bermunda Triangle. The portal and the world to which it links was built by the 'Scorpians' a race of extraterrestrials. They created it as an experiment and populated it with dinosaurs and other life indigeneous to Mesozoic Earth. The Scorpians also built The Tower of Time, a massive spiral tower in which each level simulated different periods from Earth's history.

First appearance: Super Mario Bros.
Author/Creator: Rocky Morton, Annabel Jankel, Roland Joffé, Parker Bennett, Terry Runte and Ed Solomon
Media: Film
Year: 1993
Located: A dystopian parallel world accessed via an interdimensional portal in a cave beneath the Brooklyn Bridge
Plot/Premise: Mario and Luigi, two wacky plumbers, undertake a daring quest to save a princess in "Dinohattan" -- a hidden world where the inhabitants evolved from dinosaurs. Mario and Luigi face deadly challenges from a diabolical lizard king and must battle giant reptilian goombas, outwit misfit thugs and undermine a sinister scheme to take over the world.

The Koopahari Desert surrounding Dinohatten