Long ago, an alien named Keeper entrusted the greatest power in the universe to dinosaurs. Millions of years later, the Energems were found, but Sledge came up with a devious way to steal them. Now after many battles, he has the ultimate plan... Can our heroes and a new ally save the world?
Fury sets off a silent alarm in the ranger base, alerting the rangers to his presence there. They hurry back to find him and Keeper dueling in the Dino Base. Blasting him away and driving off his vivicks and spikeballs, Fury flees, and the rangers consider their next move; but Sledge preempts them with a transmission, and a promise: He's selling the earth for scrap, and then prying the energems from their frozen hands.
The rangers wonder whether he could actually do this, when an earthquake hits Amber Beach. The rangers discover that the planet is being towed out of its orbit by none other than Sledge. The five Greenzilla eggs form anchor points on the Earth's crust, allowing him to use an electronet to bind the anchors together and literally pull the Earth with him. In order to save the Earth, the rangers need to unlock the full power of the Energems, which means destroying the Dark Energem. Even after hitting it with all the power they had, it wasn't even damaged, but Riley comes up with an interesting thought since the Dark Energem was created from pure darkness, light should be strong enough to destroy it, but where would they get that much light?
The answer comes in the form of teamwork, specifically in the population of the Earth working together. Everyone facing the sun holds up a mirror, as instructed by the rangers, and the combined reflected and focused light is enough to weaken the Energem, enough for the rangers to finish it off. And just in time too, as the Earth gets colder and colder the further it moves. But a problem soon appears... The Dark Energem's destruction has caused a rip in spacetime, forming a black hole that destroys both Sledge's ship, and the Earth! Keeper unlocks the full power of the Energems, granting the team the ability to save the future by changing the past, specifically by stopping Sledge before he could cause damage.
The rangers pass through the vortex, ending back in the Cretaceous Period. While the auxiliary rangers infiltrate the ship, Ivan and the core rangers (minus Tyler) aid Keeper, who is initially distrusting of the teens. The rangers prove their loyalty and courage by summoning their Energems, proving their bond with them transcends time, and the six fight Fury and Sledge one more time. Fury is shocked that Ivan can counter every one of his moves, as he doesn't remember fighting him. Fury locates the remaining Energems, but it is a trap, and Keeper's crystal bomb that was originally on the latter's ship blows up, killing Fury. Tyler reveals he switched the Energems and urges the others to keep fighting to distract Sledge. Up in orbit, Heckyl and the auxiliary rangers are sabotaging the ship, plotting a course straight for the sun.
Sledge engages the rangers once more, pissed they killed off his trusted general. He walks through everything they throw at him, and fights Tyler one on one, with Tyler using the Supercharge mode to even the odds. Even this is not enough to battle Sledge, and he gets ready to call on his little surprise, which the rangers already know to be the Magnabeam, confusing Sledge. Nevertheless, he grows and attacks again, almost crushing the rangers, and without a Megazord to battle him, they are driven back. Fortunately, Heckyl and the others are able to ensnare him with an electronet, and hoist him into space, as well as locking Poisandra up in an empty cell and knocking Wrench out. The Plesio Zord flees, leaving the ship to crash into the sun, killing Sledge and his crew.
Keeper thanks the rangers for their aid and lets them return home. Koda and Ivan elect to return to their normal time periods, while the others return to the present. Keeper tasks Heckyl and Zenowing with recovering the Dark Energem from Sentai 6 before Arcanon can get his hands on it, saving the planet. Keeper makes Heckyl a new guardian, the 'Keeper of the Dark Energem'. Keeper and the others leave the Cretacious, with his farewell message being that order has been restored.
The rangers arrive back in the present day, but with one big difference: since the asteroids Sledge was collecting never hit the Earth, the dinosaurs were never wiped out. And as the rangers soon discover, the museum is now a Dinosaur Zoo, and they are the dinosaur keepers. The emergency that Kendall was alerted to was that the triceratops has indigestion, and the zookeepers need the experts to help it. The rangers begin this new chapter of their lives in a new world...
- Alternate Continuity: A possible implication of the ending, since after the Reset Button ending, dinosaurs are alive and well in the 21st Century!
- It's possible it was already an Alternate Continuity before the Reset Button.
- And the Adventure Continues: With the Rangers, minus Ivan and Koda, living in an alternate timeline where the dinosaurs never went extinct.
- Apocalypse How: The Earth gets destroyed when it is pulled into a black hole. Before that, pulling it out of orbit makes the temperature slowly plummet.
- Back for the Finale: Kaylee, Mr. Watkins, Matt, and Zach all appear to help the Rangers' plan to destroy the Dark Energem.
- Big "WHAT?!":
- Fury when the Rangers arrive to save Keeper and later when the crystal bomb kills him.
- Sledge when he realizes that Tyler swapped the Energems with Keeper's crystal bomb and later when he is taken by the electronet courtesy of Heckyl.
- Bookends: Several references to the beginning of the series.
- First of all, the alliterative titles.
- When Tyler swaps the Energems for Keeper's crystal bomb, Sledge says "IT'S A BOMB!" before it explodes.
- Before Sledge collides with the sun, he says, "I'll make you pay for this, Keeper, if it's the last thing I do!"
- The series began with Keeper accidentally causing the extinction of the dinosaurs, and it ends with the rangers helping him save them.
- Character Death:
- Fury is killed by Keeper's crystal bomb.
- Then Sledge, Poisandra, and Wrench are killed when Sledge's ship collides with the sun.
- Double-Meaning Title: One would think it refers to the rangers preventing the extinction of humanity, but by the end, they've also prevented the extinction of dinosaurs.
- Grand Finale: Part 4 of 4: Sledge and co pull off their grand plan, bargaining the Energems for the planet. The Earth gets destroyed by a black hole, and the rangers resort to time travel to fix it.
- Hurl It into the Sun: Heckyl sends Sledge's ship into the sun, taking Sledge with it.
- In Spite of a Nail: Despite the rangers changing the course of history, the present day is pretty much exactly the same as they left it. The only real difference is that dinosaurs are not extinct and "Amber Beach Museum" is now "Amber Beach Dinosaur Zoo".
- Nice Job Breaking It, Hero!: The Rangers blast the Dark Energem with help from the people of Earth hoping to destroy it. They do but end up causing a black hole which destroys the Earth, necessitating a trip back into the past to keep Sledge from accidentally bombarding the prehistoric era with the asteroids and stop him there from keeping the events of the future from happening.
- Record Needle Scratch: When Tyler correctly guesses that Sledge is using the Magnabeam to make himself grow, the music scratches to a halt.
- Reset Button: The Rangers have to time travel to the past after they accidentally get the Earth sucked into a black hole.
- Say My Name: Sledge yells Fury's name after the latter gets killed.
- Set Right What Once Went Wrong: The rangers travel back to the Cretaceous to stop Sledge before he becomes a threat in the present, in order to bring back the Earth. It inadvertently saves the dinosaurs, but history compensates.
- Somebody Set Up Us the Bomb: Tyler swaps the Energems for Keeper's crystal bomb towards the end of the episode. The explosion kills Fury.
- Storming the Castle: Heckyl and the others storm Sledge's ship as part of their plan to undo the events of the future.
- Where It All Began: More like "When It All Began".