First appearance: Lost Continent
Author/Creator: Sam Newfield, Orville H. Hampton, Richard H. Landau, Carol Young
Media: Film
Year: 1951
Located: South Pacific island
Plot/Premise: A mission heads to the South Pacific to retrieve an atomic rocket that vanished. Their plane crashes on a remote tropical island. They find a lone native girl who indicates something fell from the sky onto a forbidding plateau which dominates part of the island. The party reaches the top despite numerous obstacles, and discovers a lush jungle inhabited by dinosaurs. Some die during the climb, others are killed by the presumed-extinct animal life, but two return to the flatland with a critical component of the rocket. They escape, along with the island girl, as a dormant volcano erupts and destroys the island.

First appearance: "4-Color" #595, Dell Publishing
Author/Creators: Rex Maxon, Matthew H. Murphy, Gaylord Du Bois and Paul S. Newman
Media: Comic
Year: 1954
Located: A deep canyon in the Carlsbad area of New Mexico that perhaps leads to a prehistoric sub-universe
Plot/Premise: Turok was a brave Kiowa warrior living some time in the 1800's before the arrival of white men. He and a young companion, Andar, wander into a savage prehistoric land they call Lost Valley and find themselves cut off from their homeland and people. They wander around Lost Valley, encountering cavemen and hungry dinosaurs (which they call "honkers"), searching for a way out. Fortunately, on their journeys, they discover a poisonous plant with highly toxic berries. They smear the tips of their arrows with these berries and now even the biggest, nastiest honker is no longer a threat.
Sequels/Other appearances: Turok (1993, Valiant Comics)
Adaptations: Turok: Dinosaur Hunter (1997, Video Game), Turok (rebooted premise)

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: King Dinosaur
Author/Creator: Bert I. Gordon, Tom Gries
Media: Film
Year: 1955
Located: Nova, a planet that has wandered into our solar system
Plot/Premise: Four astronauts in 1960 travel to a planet called Nova that has "settled" into our solar system. The crew begins to study the planet to see if it's able to withstand a possible Earth colony. After first discovering normal earth animals such as a lemur and an alligator, they soon encounter giant insects, dinosaurs, and the titular King Dinosaur.

Author/Creator: Charlotte Knight (story), Robert Creighton Williams (screenplay) (as Bob Williams), Christopher Knopf (screenplay), Ray Harryhausen (special effects), Nathan Juran (Director)
First appearance: 20 Million Miles to Earth
Media: Film
Year: 1957
Located: Venus
Plot/Premise: When the first manned flight to Venus returns to Earth, the rocket crash-lands in the Mediterranean near a small Italian fishing village. The locals manage to save one of the astronauts Colonel Calder, the mission commander. A young boy also recovers what turns out to be a specimen of an alien creature. Growing at a fantastic rate, this sulfur-digesting exosaur manages to escape and eventually threatens the city of Rome forcing the military to take drastic action.

First appearance: The Land Unknown
Author/Creator:
Media: Film
Year: 1957
Located: Antarctica, 3000 feet below sea level
Plot/Premise: A Navy expedition is sent to explore a mysterious warm-water region shrouded in the ice of Antarctica. When a fierce storm drives them into a cloud bank, their helicopter is disabled by a collision with a pterodactyl. Descending through the heavy fog into a deep chasm, they encounter a hot, tropical landscape of prehistoric terror.
Adaptations: The Land Unknown (Comic, 1957, Dell) by Alex Toth