Ash, Misty, and Brock are walking down a path in Grandpa Canyon, and Ash spots a long procession of people on the path in front of him. Upon closer inspection, Ash notices that they all are packing picks and shovels. Before we are faced with the daunting prospect of Ash having to figure this one out himself, Gary shows up. He too is carrying a pickaxe, and is dressed up like Indiana Jones. He informs Ash that ancient fossils were found in Grandpa Canyon and all these people are here to mine them. (Gary calls it "The Great Fossil Rush") Of course, Gary is there to mine all the fossils before anyone else, and leaves Ash with an insult ("can't waste time with a loser like you.") and heads off towards the fossil dig. Ash decides to try and dig up more Pokemon fossils than Gary, and drags Misty and Brock along despite protests. We notice Jigglypuff hiding behind some rocks, though…
At the dig, Gary is somehow able to come up with the first Pokemon fossil. Unfortunately, it's fossilized Pokemon dung. Ash, Misty, and Brock are overlooking the proceedings from the canyon rim. They are about to start down the path towards the quarry floor when they notice… Meowth! Yes, its Team Rocket, and they plan to use dynamite to blow up the canyon and then pick the fossils out of the broken rock afterwards. They seem to have forgotten about what will happen to all the people mining fossils on the canyon floor, but Ash, smart lad that he is, grasps the concept that millions of tons of rock flying through the air can cause bodily damage. Misty and Brock run to warn people in the canyon, while Ash calls out Squirtle to put out the fuse to the dynamite, and TR gives chase. Squirtle, however, couldn't hit a white whale on a black background, and misses the fuse again and again. James, running after Ash, trips on a rock, falls into Jessie, and starts a chain reaction then ends with everyone in a tangle at the entrance to the cave that has the dynamite. Just before the dynamite explodes, Pikachu gets free, panics, and blasts the dynamite with thundershock. The resulting explosion causes a rip in the canyon ground, and both Ash and TR fall through. The opening is then covered with rocks. Misty and Brock run up, and, with the lone survivor, Squirtle, begin digging Ash out.
Underground, Ash and TR come to. After TR and Ash blame each other for the explosion, they start trying to figure out a way out. Pikachu, however, notices some red eyes in the dark shadows. It seems that the explosion awakened some prehistoric Pokemon - Kabuto, Kabutops, Omanyte and Omastar - and they are REALLY cranky. TR tries to capture them, because they are thought to be extinct and have never been seen alive, but these Pokemon aren't in the mood. The Omastars, Kabutos, and Omanytes proceed to wipe the ground with Team Rocket, and Ash has to run for his life when Charmeleon refuses to battle two Kabutops. (Pikachu's electricity is ineffective)
On the surface, meanwhile, the excavation project is going slowly. Officer Jenny shows up announcing that the bulldozers can't get this far down into the canyon, but she promises to go get some help. Brock then calls out some rock Pokemon, and they start digging again. Underground again, TR is getting beaten up pretty badly, and Ash is cornered by the Kabutops, when all of the sudden they all disappear into the dark recesses of the cave. TR gets up and rejoices, but Ash hears something else coming out of the dark. It's an Areodactyl, and it too is pissed off. It's prehistoric, its hungry, it's a carnivore, and it thinks it has stumbled upon dinner. Charmeleon tries to battle it, thinking he's hot stuff, but gets knocked out as soon as Aerodactyl hits him. Aerodactyl grabs Ash just as Misty and Brock break thru, and flies up out of the opening to the underground. It lands on a high rock, and proceeds to prepare Ash for supper. However, Charmeleon, who REALLY wants to battle Aerodactyl, evolves into Charizard and forestalls Aerodactyl's dinner plans. Aerodactyl flies off, and Charizard gives chase. Charizard can't catch up to Aerodactyl, and when he fire blasts Aerodactyl, he gets Ash burned as well. On the ground, Jigglypuff makes an appearance, and Misty coaxes a song out of it. Jigglypuff starts singing, and everyone starts to nod off, including Aerodactyl and Charizard. Misty didn't plan ahead real well, because if Aerodactyl falls asleep in midair, Ash has a mighty long fall to look forward to. Charizard keeps his fingers in his ears to stop the effects of Sing just long enough to catch Ash and land. Aerodactyl falls from the sky back into the underground cave, and the concussion from it hitting the ground closes the opening back up with rocks. Jigglypuff does the marker doodle thing after everyone nods off, then disappears.
After everyone wakes up, Jenny clears everyone out of the canyon, and announces there will be no more digging. (You did not see an Aerodactyl, You were never here, and neither was I) Ash and Co. walk out of Grandpa Canyon, and Ash announces he found a strange egg lying next to him when he woke up. Before he can put it back into his pack, Brock takes from him, announces he'll raise the egg and runs off. Meanwhile...
TR is STILL in the ancient Pokemon cave, trying not to wake up Aerodactyl and the rest of the prehistoric Pokemon. James sneezes though, and, uh, we leave TR before things get ugly.…