|This article is about a/an episode in Power Rangers Dino Thunder.|
With Dr. Oliver "on sick leave" (due to his demorphing troubles), Dr. Anton Mercer, Trent's adoptive father and alter ego of Mesogog, is brought in by Principal Randall as the substitute science teacher. He immediately stages a field trip to the Reefside Museum, which leads to Kira ending up in a storage room where she is forced to submit to the will of a hypnotic dinosaur skull. The creature gives her a sour attitude towards her friends, and ultimately leads her to Tommy's lab to steal a bone she had recently noticed while helping him take inventory. The bone is revealed to be the final component of Fossilador, a hypnotic dinosaur monster created by Tommy and Mercer years ago! Can our heroes stop her before she restores the bony creature?
The Rangers agree that they must keep an eye on Trent. Trent is watching them from against the school lockers. Trent doesn't seem too threatened by the Rangers watching him. Trent gets paged to meet with Principal Randall, who tries to get through to Trent, but he doesn't back down. None of which bothers Trent as he enjoys the cat and mouse game he is playing with Principal Randall as she asked him about joining a team, which Trent mentions that he was asked to be on one, but said that the team were losers and didn't want to be on a losing team.
In class, the students were buzzing over who would be the new teacher, while Dr. Oliver was gone. Cassidy had heard from a reliable source that it was an eighty-year kindergarten teacher from Ohio. Principal Randall introduceds Anton Mercer as the substitute teacher for Dr. Oliver, which surprised Conner, Ethan, Kira, especially Trent, who surprised as he picked up his head and stare at his dad in amazement. Dr. Anton Mercer begins the class by passing out permission forms for a field trip to the dinosaur museum. The class isn't pleased with Dr. Mercer as their new teacher. The Rangers argue that Anton shouldn't be watching other people's kids, when he can't take care of his own. Anton tries to talk to Trent and wanted him home, but Trent won't listen to him and didn't want to be around his dad and walked away from him, but Anton wants to talk to him later. Kira finds a bone in the Lab, but Tommy says it should be put away for safe keeping.
Meanwhile, at the Dinosaur Exhibit - at the museum... Anton Mercer takes his class on a field trip. Meanwhile, Kira stumbles upon Fossilador - a mind controlling fossil. Kira is put under the Fossilador's evil control Kira blows off the other Rangers at the Cyberspace. She later tells Dr. Oliver that she has spotted a Dinozord egg in the forest.
Tommy goes off to investigate. Meanwhile, Kira infiltrates the Dino Lab - and steals the missing bone. Tommy returns to discover the bone is missing, and says that it was part of an experiment that was out of control. The incomplete Thundersaurus Megazord must fight against Fossilador. Kira comes to their rescue once she is free from the spell - with the aid of the Pterazord. Meanwhile, Tommy faces off against Zeltrax and the Triptoids. With instructions from Dr. Oliver, the Thundersaurus Megazord finally destroys Fossilador.
Kira wonders why the Fossilador was being stored in Anton Mercer's museum. Anton Mercer searches for a way to free himself from Mesogog. But the transformation is too powerful, and he is overcome by it. After becoming Mesogog, he promises that his plan to bring back the era of the dinosaurs will soon come to pass...Power Rangers or no Power Rangers.
- When entering the museum, Kira says that she gets a "creepy vibe" from the T-Rex outside like it could move. This is ironic, considering that the same dinosaur did, in fact, attack Dr. Oliver in Day of the Dino. Dr. O must not have ever told the other Rangers about the incident.
- The mechanical t-rex that attacked Tommy in Day of the Dino, Part 1 has been either repaired or replaced.
- First use of the Triptoids since Game On